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  • 1.
    Abramowicz, Konrad
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Hérbert-Losier, Kim
    National Sports Institute of Malaysia.
    Pini, Alessia
    MOX – Department of Mathematics, Politecnico di Milano.
    Schelin, Lina
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics. Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Strandberg, Johan
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Vantini, Simone
    MOX – Department of Mathematics, Politecnico di Milano.
    An inferential framework for domain selection in functional anova2014In: Contributions in infinite-dimensional statistics and related topics / [ed] Bongiorno, E.G., Salinelli, E., Goia, A., Vieu, P, Esculapio , 2014Conference paper (Refereed)
    Abstract [en]

    We present a procedure for performing an ANOVA test on functional data, including pairwise group comparisons. in a Scheff´e-like perspective. The test is based on the Interval Testing Procedure, and it selects intervals where the groups significantly differ. The procedure is applied on the 3D kinematic motion of the knee joint collected during a functional task (one leg hop) performed by three groups of individuals.

  • 2. Abramowicz, Konrad
    et al.
    Häger, Charlotte K.
    Pini, Alessia
    Schelin, Lina
    Sjöstedt de Luna, Sara
    Vantini, Simone
    Nonparametric inference for functional-on-scalar linear models applied to knee kinematic hop data after injury of the anterior cruciate ligament2018In: Scandinavian Journal of Statistics, Vol. 0, no 0Article in journal (Refereed)
    Abstract [en]

    Motivated by the analysis of the dependence of knee movement patterns during functional tasks on subject-specific covariates, we introduce a distribution-free procedure for testing a functional-on-scalar linear model with fixed effects. The procedure does not only test the global hypothesis on the entire domain but also selects the intervals where statistically significant effects are detected. We prove that the proposed tests are provided with an asymptotic control of the intervalwise error rate, that is, the probability of falsely rejecting any interval of true null hypotheses. The procedure is applied to one-leg hop data from a study on anterior cruciate ligament injury. We compare knee kinematics of three groups of individuals (two injured groups with different treatments and one group of healthy controls), taking individual-specific covariates into account.

  • 3.
    Alt Murphy, Margit
    et al.
    Institute of Neuroscience and Physiology, Rehabilitation Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Kinematic analysis of the upper extremity after stroke: how far have we reached and what have we grasped?2015In: Physical Therapy Reviews, ISSN 1083-3196, E-ISSN 1743-288X, Vol. 20, no 3, p. 137-155Article in journal (Refereed)
    Abstract [en]

    Background: Consequences of stroke frequently comprise reduced movement ability of the upper extremity (UE) and subsequent long-term disability. Clinical scales are used to monitor and evaluate rehabilitation but are often insufficient, while technological advances in 3D motion capture provide detailed kinematics to more objectively quantify and interpret movement deficits. Objectives: To provide a comprehensive overview of research using kinematic movement analysis of the UE in individuals post-stroke with focus on objectives, methodology and findings while highlighting clinical implications and future directions. Major Findings: A literature search yielded 93 studies categorised into four groups: comparative (healthy, stroke, task condition), intervention (clinical trials), methodological and longitudinal. The majority of studies used optoelectronic systems, investigated discrete reaching and involved mainly individuals with moderate or mild stroke impairment in chronic stage. About 80% of the studies were published after year 2004. Speed-related variables were most frequently addressed followed by smoothness indicators, joint angles and trunk displacement. Movements in the hemiparetic side are generally slower, less smooth and show a compensatory movement pattern. Task specificity is crucial for kinematic outcomes. Tables summarising the main characteristics, objectives and results of all included studies are provided. Conclusions: There is still a lack of studies addressing reliability and responsiveness and involving more complex, everyday UE tasks with ecological validity. To facilitate the use of UE kinematic movement analysis in clinics, a research-based simpler data handling with pre-defined output for the results, as commonly used in gait analysis, is warranted.

  • 4.
    Anens, Elisabeth
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Kristensen, Bo
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Reactive grip force control in persons with cerebellar stroke: effects on ipsilateral and contralateral hand2010In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 203, no 1, p. 21-30Article in journal (Refereed)
    Abstract [en]

    This study investigates the cerebellar contribution to reactive grip control by examining differences between (22-48 years) subjects with focal cerebellar lesion due to ischaemic stroke (CL) and healthy subjects (HS). The subjects used a pinch grip to grasp and restrain an instrumented handle from moving when it was subject to unpredictable load forces of different rates (2, 4, 8, 32 N/s) or amplitudes (1, 2, 4 N). The hand ipsilateral to the lesion of the cerebellar subjects showed delayed and more variable response latencies, e.g., 278 +/- 162 ms for loads delivered at 2 N/s, compared to HS 180 +/- 53 ms (P = 0.005). The CL also used a higher pre-load grip force with the ipsilateral hand, 1.6 +/- 0.8 N, than the HS, 1.3 +/- 0.6 N (P = 0.017). In addition, the contralateral hand in subjects with unilateral cerebellar stroke showed a delayed onset of the grip response compared to HS. Cerebellar lesions thus impair the reactive grip control both in the ipsilateral and contralateral hand.

  • 5.
    Arumugam, Ashokan
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Markström, Jonas L.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte K.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Introducing a novel test with unanticipated medial/lateral diagonal hops that reliably captures hip and knee kinematics in healthy women2018In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380Article in journal (Refereed)
    Abstract [en]

    Despite a vast literature on one-leg hops and cutting maneuvers assessing knee control pre/post-injury of the anterior cruciate ligament (ACL), comprehensive and reliable tests performed under unpredictable conditions are lacking. This study aimed to: (1) assess the feasibility of an innovative, knee-challenging, one-leg double-hop test consisting of a forward hop followed by a diagonal hop (45°) performed medially (UMDH) or laterally (ULDH) in an unanticipated manner; and (2) determine within- and between-session reliability for 3-dimensional hip and knee kinematics and kinetics of these tests. Twenty-two healthy women (22.3 ± 3.3 years) performed three successful UMDH and ULDH, twice 1–4 weeks apart. Hop success rate was 69–84%. Peak hip and knee angles demonstrated moderate to excellent within-session reliability (intraclass correlation coefficient [ICC] 95% confidence interval [CI]: 0.67–0.99, standard error of measurement [SEM] ≤  3°) and poor to excellent between-session reliability (ICC CI: 0.22–0.94, SEM ≤ 3°) for UMDH and ULDH. The smallest real difference (SRD) was low (≤ 5°) for nearly all peak angles. Peak hip and knee moments demonstrated poor to excellent reliability (ICC CI: 0–0.97) and, in general, moments were more reliable within-session (SEM ≤ 0.14 N.m/kg.m, both directions) than between-session (SRD ≤ 0.43 N.m/kg.m). Our novel test was feasible and, in most but not all cases, provided reliable angle estimates (within-session > between-session, both directions) albeit less reliable moments (within-session > between-session, both directions). The relatively large hip and knee movements in the frontal and transverse planes during the unanticipated hops suggest substantial challenge of dynamic knee control. Thus, the test seems appropriate for evaluating knee function during ACL injury rehabilitation.

  • 6.
    Björklund, Martin
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden.
    Djupsjöbacka, Mats
    Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden.
    Svedmark, Åsa
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Effects of tailored neck-shoulder pain treatment based on a decision model guided by clinical assessments and standardized functional tests: a study protocol of a randomized controlled trial2012In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 13, article id 75Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: A major problem with rehabilitation interventions for neck pain is that the condition may have multiple causes, thus a single treatment approach is seldom efficient. The present study protocol outlines a single blinded randomised controlled trial evaluating the effect of tailored treatment for neck-shoulder pain. The treatment is based on a decision model guided by standardized clinical assessment and functional tests with cut-off values. Our main hypothesis is that the tailored treatment has better short, intermediate and long-term effects than either non-tailored treatment or treatment-as-usual (TAU) on pain and function. We sub-sequentially hypothesize that tailored and non-tailored treatment both have better effect than TAU.

    METHODS: 120 working women with minimum six weeks of nonspecific neck-shoulder pain aged 20-65, are allocated by minimisation with the factors age, duration of pain, pain intensity and disability in to the groups tailored treatment (T), non-tailored treatment (NT) or treatment-as-usual (TAU). Treatment is given to the groups T and NT for 11 weeks (27 sessions evenly distributed). An extensive presentation of the tests and treatment decision model is provided. The main treatment components are manual therapy, cranio-cervical flexion exercise and strength training, EMG-biofeedback training, treatment for cervicogenic headache, neck motor control training. A decision algorithm based on the baseline assessment determines the treatment components given to the each participant of T- and NT-groups. Primary outcome measures are physical functioning (Neck Disability Index) and average pain intensity last week (Numeric Rating Scale). Secondary outcomes are general improvement (Patient Global Impression of Change scale), symptoms (Profile Fitness Mapping neck questionnaire), capacity to work in the last 6 weeks (quality and quantity) and pressure pain threshold of m. trapezius. Primary and secondary outcomes will be reported for each group with effect size and its precision.

    DISCUSSION: We have chosen not to include women with psychological ill-health and focus on biomedical aspects of neck pain. Future studies should aim at including psychosocial aspects in a widened treatment decision model. No important adverse events or side-effects are expected.

    Trial registration: Current Controlled Trials registration ISRCTN49348025.

  • 7.
    Björklund, Martin
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Djupsjöbacka, Mats
    Svedmark, Åsa
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Effects of tailored versus non-tailored treatment on pain and pressure pain threshold in women with non-specific neck pain: A randomized controlled trial2014Conference paper (Refereed)
  • 8.
    Dahlgren, Gunilla
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Carlsson, Daniel
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Moorhead, Anne
    Health and Rehabilitation Sciences Research Institute, School of Health Sciences, University of Ulster, Co. Antrim, Northern Ireland, United Kingdom.
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    McDonough, Suzanne M
    Health and Rehabilitation Sciences Research Institute, School of Health Sciences, University of Ulster, Co. Antrim, Northern Ireland, United Kingdom.
    Test-retest reliability of step counts with the ActivPAL™ device in common daily activities.2010In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 32, no 3, p. 386-90Article in journal (Refereed)
    Abstract [en]

    The ActivPAL device is a well-established physical activity monitor for assessment of physical activity. AIM: To investigate test-retest reliability of step counts and establish minimal detectable changes (MDC) in step count to account for intra device error over time in various physical activities. METHODS: Healthy participants (n=24, age range, 19-28 years) performed activities on two occasions, 1 week apart, in a laboratory setting; self-paced floor walking, treadmill walking at three different speeds (3.2 km/h, 4.5 km/h and 4.5 km/h with incline), treadmill jogging (8.0 km/h), stair walking and cycling on an exercise bike at three speeds (45 rpm, 60 rpm and 75 rpm). Relative reliability was calculated using intraclass correlation coefficient (ICC) and Spearman correlation. Absolute reliability was assessed using standard error of measurement (SEM) and coefficient of repeatability (CR). RESULTS: The ActivPAL showed high to very high relative reliability for treadmill walking at all speeds and stair walking, while self-paced normal floor walking showed moderate reliability. The absolute reliability was the best for treadmill walking activities, slightly increased for self-paced walking, followed by stair walking and jogging. The use of activity monitors during cycling has been questioned and our results confirm a low absolute and relative reliability. MDC values varied according to the type of activity e.g. treadmill walking 4.5 km/h (10 steps), walking on the floor (45 steps). Data loss in this study (10-13%) was higher than previously reported. CONCLUSIONS: The ActivPAL is reliable for treadmill walking, jogging and self-paced walking. MCD varies according to the activity and should be considered when establishing true change over time.

  • 9.
    Eklund, Elsine
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Svensson, Elisabeth
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Functional performance and experienced limitations of daily life in people with charcot-marie-tooth's disease2007Conference paper (Other academic)
  • 10.
    Eklund, Elsine
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Svensson, Elisabeth
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Hand function and disability of the arm, shoulder and hand in Charcot-Marie-Tooth disease2009In: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 31, no 23, p. 1955-1962Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim of the present study was to examine hand function and disability in persons with Charcot-Marie-Tooth disease (CMT) and to evaluate the possible correlations between hand function and disability.

    Methods: Nine male, 11 female (24-73 yrs) persons with CMT in northern Sweden and a matched control group of 18 men, 22 women (21-73 yrs) participated in the study. Measurements applied were tests of dexterity (Box and Block Test; Nine-Hole Peg test), grip strength (Grippit®), tactile gnosis (Shape Texture Identification test) and upper-limb disability (Disabilities of the Arm Shoulder and Hand questionnaire, DASH).

    Results: Hand function in CMT was reduced (p<0.001) to about 60% of normal, as indicated by each of the separate outcome measures as well as by a constructed summary index of hand function. DASH score median was 38.8 (range 0-66.7) and was clearly related to hand function (r=0.64-0.83).

    Conclusion: Reduced hand function in CMT was found at different dimensions according to the International Classification of Functioning, Disability and Health (ICF). We suggest that DASH can be used in persons with CMT though clinicians should be aware that patients might score lower than expected, possibly due to a long process of adaptation when learning to live with a slowly progressive disease.

  • 11. Eliasson, AC
    et al.
    Rösblad, Birgit
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Control of reaching movements in 6-year-old prematurely born children with motor problems: an intervention study2003In: Advances in Physiotherapy, ISSN 1403-8196, E-ISSN 1651-1948, Vol. 5, no 1, p. 33-48Article in journal (Refereed)
    Abstract [en]

    The aim was to improve the control of reaching movements in prematurely born children with impaired coordination. Fifteen 6-year-old prematurely born children (birth weight < 1500 g) practised mouse-controlled computer games daily for 4 weeks. In addition, as a control condition, each child practised trampoline jumping for an equally long perios. The outcome was measured in terms of: (1) computer game skill, (2) kinematic analysis of planar reaching movements on a digitizing tablet, and (3) motor performance measured with the Movement ABC. After intervention, all the assessments used showed an improvement although only the skill in performing the computer game was clearly related to the type of intervention. Lack of tight correlation between computer game practice and performance on the digitizing tablet might be due to minor but crucial differences in control aspects between the task. The present results indicate that the expectation of transfer even to every similar tasks should be low. The findings thus support a task-specific approach to practice, while corroborating the positive impact of non-specific intervention.

  • 12.
    Fredrik, Öhberg
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Nilsson, Kjell G
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Orthopaedics.
    Edström, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Gustavsson, Ola
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Gait analysis using a portable motion sensor system: measurements in subjects with hip implant as compared with healthy controls2013In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 38, no suppl 1, p. 99-100Article in journal (Refereed)
    Abstract [en]

    Introduction: There is an increase of age related diseases such as hip joint arthritis, something that is often treated with hip replacement surgery. The aim of this study was to quantify movement function and its effect on quality of life in persons treated with hip implant, in comparison to matched asymptomatic controls.

    Patients/Materials and Methods: This is an ongoing study, and so far, 2 asymptomatic subjects (CTRL, age 50 ± 13 years, BMI 23 ± 2), and 4 subjects with hip implant (HIP, age 51 ± 15 years, BMI 25 ± 3), have been analyzed. The HIP group received their implant 2.6 ± 1.1 years ago and finished their rehabilitation 1.6 ± 1.1 years ago. Hip dysfunction and Osteoarthritis Outcome Score (HOOS) was used to assess the subject's hip function and its associated problems. A functional calibration (flexion/abduction movements) was done and each subject then performed 5 repetitions of gait (approx. 25 left/right gait cycles). Movement was registered with a custom-developed portable motion sensor system, where each sensor consisted of a tri-axial accelerometer and gyroscope. Sensors were placed on pelvis and each thigh and shank. Further calculations were done in MATLAB (v7.12 R2011a, Mathworks). Cosine rotation matrices were extracted by functional sensor-to- segment-calibration and sensor fusion [1], and hip and knee angles were obtained as Euler angles.

    Results: Preliminary results indicated larger range in hip rotation and smaller range of knee flexion during gait in HIP group than in the CTRL group (Fig. 1). HOOS profile (Fig. 2) indicated that hip function during sports (SP) and the general quality of life (QOL) were lower in the HIP group.

    Fig. 1. 

    Mean and SD of hip and knee angle over 15 gait cycles in one HIP subject (blue) as compared with the CTRL group (black). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

    Figure optionsFig. 2. 

    HOOS profiles in HIP (blue square) and CTRL group (black). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

    Figure options

    Discussion and conclusions: Motion patterns during gait seemed to be negatively affected in subjects with hip implant, even after the rehabilitation program was completed and even though the HOOS profiles indicated a relative good hip function.

    Reference

    • [1]
    • J. Favre, B.M. Jolles, O. Siegrist, K. Aminian
    • Quaternion-based fusion of gyroscopes and accelerometers to improve 3D angle measurement

  • 13. Frykberg, G
    et al.
    Johansson, Gudrun
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Selling, Jonas
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    The “Arm Posture Score” for assessment of arm swing during gait: Evaluation of additional rotational components and different gait speeds2012Conference paper (Refereed)
  • 14.
    Frykberg, Gunilla E
    et al.
    Department of Neuroscience, Rehabilitation Medicine, Uppsala University, Sweden.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Movement analysis of sit-to-stand: research informing clinical practice2015In: Physical Therapy Reviews, ISSN 1083-3196, E-ISSN 1743-288X, Vol. 20, no 3, p. 156-167Article in journal (Refereed)
    Abstract [en]

    Background: Sit-to-stand (STS) is a crucial transfer influencing a person's independence in daily activities, as well as safety and quality of life, and is thus vital to evaluate in research and in practice. Clinical STS tests provide single values in seconds or numbers of STS. There is, however, increasing numbers of research papers reporting spatial and temporal kinematic and kinetic process STS data.

    Objectives: To provide an overview of research findings from laboratory-based movement analyses regarding phases and determinants of typical STS, characteristics of successful versus failed STS transfers, and finally STS performance in some neurological conditions.

    Major Findings: The STS transfer, previously regarded as mainly requiring lower limb muscle strength, is increasingly recognized as a complex transfer skill. Muscle strength, balance, foot position, chair height and the movement strategy are major determinants influencing STS performance. Scaling and timing of momentum generation throughout STS seems critical for success or failure. Sit-to-stand in stroke and Parkinson's disease (PD) is characterized by asymmetry in force generation and difficulties in switching movement direction, respectively. In-depth, knowledge regarding mechanisms of momentum control during STS sub-phases, STS failures, as well as exploration of variability in normal and atypical STS is still lacking.

    Conclusions: Recent research based on instrumented movement analyses has generated better understanding of movement control during STS, but the specifics are not yet reflected in clinical assessments. There seems to be a call for clinical tools capturing determinants and process characteristics of the STS transfer for a more comprehensive evaluation in rehabilitation.

  • 15.
    Frykberg, Gunilla E.
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Johansson, Gudrun M.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Schelin, Lina
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Häger, Charlotte K.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    The Arm Posture Score for assessing arm swing during gait: An evaluation of adding rotational components and the effect of different gait speeds2014In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 40, no 1, p. 64-69Article in journal (Refereed)
    Abstract [en]

    In 3D gait analysis, quantification of leg movements is well established, whereas ameasure of armswing has been lacking. Recently, the Arm Posture Score (APS) was introduced to characterize arm movements in children with cerebral palsy, including information from four variables (APS(4)) in the sagittal and frontal planes. A potential limitation of the APS is that it does not include rotational movements and has not yet been evaluated with regard to gait speed. The aims of this study were (i) to investigate the effect on APS of adding two components of arm rotation (APS(6)) and (ii) to determine the influence of gait speed on the APS measures, when applied to non-disabled adults. Forty-two subjects walked 10 m at a selfselected speed (1.34 m/s), and in addition a subgroup of 28 subjects walked at a slowspeed (0.66 m/s) set by a metronome. Data were collected from markers in a whole-body set up and by eight optoelectronic cameras. The results demonstrated significantly higher APS(6) than APS(4) values for both arms, irrespective of gait speed. Speed condition, whether self-selected or slow, had a significant effect on both APS measures. The two additional arm components are suggested to provide relevant information about arm swing during walking. However, APS(6) needs to be implemented in gait analysis of individuals with gait arm pathologies in order to further examine its utility. Werecommend that gait speed should to be taken into account when using APS measures to quantify arm swing during gait. (C) 2014 Elsevier B. V. All rights reserved.

  • 16.
    Grenholm, Anton
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Stensdotter, Ann-Katrin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Kinematic analyses during stair descent in young women with patellofemoral pain2009In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 24, no 1, p. 88-94Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Compensatory movement strategies may develop in response to pain to avoid stress on the affected area. Patellofemoral pain is characterised by intermittent periods of pain and the present study addresses whether long-term pain leads to compensatory movement strategies that remain even when the pain is absent. METHOD: Lower extremity kinematics in three dimensions was studied in stair descent in 17 women with patellofemoral and in 17 matched controls. A two-dimensional geometric model was constructed to normalise kinematic data for subjects with varying anthropometrics when negotiating stairs of fixed proportions. RESULTS: There were minor differences in movement patterns between groups. Knee joint angular velocity in the stance leg at foot contact was lower and the movement trajectory tended to be jerkier in the patellofemoral group. The two-dimensional model showed greater plantar flexion in the swing leg in preparation for foot placement in the patellofemoral group. INTERPRETATION: The results indicate that an altered stair descent strategy in the patellofemoral group may remain also in the absence of pain. The biomechanical interpretation presumes that the strategy is aimed to reduce knee joint loading by less knee joint moment and lower impact force.

  • 17.
    Grip, Helena
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    A new approach to measure functional stability of the knee based on changes in knee axis orientation2013In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 46, no 5, p. 855-862Article in journal (Refereed)
    Abstract [en]

    There is a lack of measures that quantify functional knee stability, which is of particular relevance in knee rehabilitation. Therefore, the aim of this study was to investigate the usefulness of knee finite helical axis (FHA) variables in 33 healthy subjects during two different functional tasks; One leg side hop (SH) and Two Leg Squat (TLS), and to investigate correlations of these variables with laxity. Laxity was assessed with a KT-1000 arthrometer and the Beighton Hypermobility Score. Movements were registered with an optical motion capture system. Knee rotation and translation were defined by a six degree of freedom segment model. FHA was calculated for finite steps of 20 degrees knee flexion, based on error simulations. We computed the FHA inclination, the translation along FHA and an FHA Direction Index quantifying directional changes. All variables were repeatable (average ICCs similar to 0.97 during TLS and similar to 0.83 during SH). The lower functional knee stability in SH was reflected by a significantly higher FHA Direction Index and a larger medio-lateral FHA inclination compared to those in TLS. The superior-inferior inclination was smaller during Landing in SH compared to Take-Off and TLS. Translation along FHA was generally small as expected in healthy subjects. Beighton Hypermobility Score and KT-1000 values had weak but significant correlations with FHA Direction Index and FHA translation, which show that laxity influences the functional knee stability. We conclude that FHA measures were sensitive enough to discriminate between SH and TLS. The next step is to investigate the usability of these measures in subjects with knee injury.

  • 18.
    Grip, Helena
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Johansson, Anna-Maria
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Selling, Jonas
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Rönnqvist, Louise
    Umeå University, Faculty of Social Sciences, Department of Psychology. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Boraxbekk, Carl-Johan
    Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Three dimensional kinematic analyses of finger movement control and association to brain activity responses: A pilot study on healthy individuals2017In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 57, p. 355-Article in journal (Refereed)
    Abstract [en]

    Introduction: An increased knowledge of how the brain control finger movements give us keys to understand the recovery of motor function after a brain injury. This knowledge is crucial for the development of reliable and valid assessment methods in the clinical evaluation of hand function.

    Research question: How are individual finger movements represented in the brain? Investigating the associations between kinematics and brain activity responses in healthy individuals.

    Methods: Keeping the others still. Finger movements were performed lying in the MR scanner in order to register brain activity response during the task. Optoelectronic cameras simultaneously monitored the positions of reflective markers affixed to each finger. The marker position data were used to calculate each finger's movement frequency (MF),  movement independence (“Individuation Index”, II), stationary ability (Stationarity Index, SI)[1][1]. fMRI data was analyzed by contrasting the finger movements against its active rest.

    Results: Preliminary analyses showed that (1) the finger movements primarily activate sensorimotor areas in the contralateral hemisphere (Fig. 1A), (2) that use of kinematic parameters in the fMRI analyses improved spatial specificity and (3) II engage a number of cortical areas, while MF engage fewer areas (Fig. 1B–D). Further analyses will further explore activations maps for each individual finger.

    Discussion: The inclusion of movement parameters in the fMRI analyses improves the specificity in the derived activation map, increasing the interpretability of the neural correlates of movement control. This advancement carries the promise for the development of better assessment methods of the recovery of function post-stroke with usability in rehabilitation practices.

  • 19.
    Grip, Helena
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Tengman, Eva
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Dynamic knee stability as estimated by finite helical axis methods during drop landing twenty years after anterior cruciate ligament injury2015In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 48, no 10, p. 1906-1914Article in journal (Refereed)
    Abstract [en]

    Finite helical axis (FHA) measures of the knee joint during weight-bearing tasks may capture dynamic knee stability following Anterior Cruciate Ligament (ACL) injury. The aim was to investigate dynamic knee stability during two-leg squat (TLS) and one-leg side hop (SH) in a long-term follow-up of ACL injury, and to examine correlations with knee laxity (KT-1000), osteoarthritis (OA, Kellgren–Lawrence) and knee function (Lysholm score). Participants were injured 17–28 years ago and then treated with surgery (n=33, ACLR) or physiotherapy only (n=37, ACLPT) and healthy-knee controls (n=33) were tested. Movements were registered with an optical motion capture system. We computed three FHA inclination angles, its' Anterior–Posterior (A–P) position, and an index quantifying directional changes (DI), during stepwise knee flexion intervals of ∼15°. Injured knees were less stable compared to healthy controls' and to contralateral non-injured knees, regardless of treatment: the A–P intersection was more anterior (indicating a more anterior positioning of tibia relative to femur) positively correlating with high laxity/low knee function, and during SH, the FHA was more inclined relative to the flexion–extension axis, possibly due to reduced rotational stability. During the TLS, A–P intersection was more anterior in the non-injured knee than the injured, and DI was higher, probably related to higher load on the non-injured knee. ACLR had less anterior A–P intersection than ACLPT, suggesting that surgery enhanced stability, although rotational stability may remain reduced. More anterior A–P intersection and greater inclination between the FHA and the knee flexion–extension axis best revealed reduced dynamic stability ∼23 years post-injury.

  • 20.
    Grip, Helena
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Tengman, Eva
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Quantifying motor control of the knee during side hops - healthy subjects and subjects ~20 years after anterior cruciate ligament injury.2012Conference paper (Refereed)
  • 21.
    Grip, Helena
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Tengman, Eva
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte K
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Dynamic knee stability estimated by finite helical axis methods during functional performance approximately twenty years after anterior cruciate ligament injury2015In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 48, no 10, p. 1906-1914Article in journal (Refereed)
    Abstract [en]

    Finite helical axis (FHA) measures of the knee joint during weight-bearing tasks may capture dynamic knee stability following Anterior Cruciate Ligament (ACL) injury. The aim was to investigate dynamic knee stability during two-leg squat (TLS) and one-leg side hop (SH) in a long-term follow-up of ACL injury, and to examine correlations with knee laxity (KT-1000), osteoarthritis (OA, Kellgren-Lawrence) and knee function (Lysholm score). Participants were injured 17-28 years ago and then treated with surgery (n=33, ACL(R)) or physiotherapy only (n=37, ACL(PT)) and healthy-knee controls (n=33) were tested. Movements were registered with an optical motion capture system. We computed three FHA inclination angles, its' Anterior-Posterior (A-P) position, and an index quantifying directional changes (DI), during stepwise knee flexion intervals of similar to 15 degrees. Injured knees were less stable compared to healthy controls' and to contralateral non-injured knees, regardless of treatment: the A-P intersection was more anterior (indicating a more anterior positioning of tibia relative to femur) positively correlating with high laxity/low knee function, and during SH, the FHA was more inclined relative to the flexion-extension axis, possibly due to reduced rotational stability. During the TLS, A-P intersection was more anterior in the non-injured knee than the injured, and DI was higher, probably related to higher load on the non-injured knee. ACL(R) had less anterior A-P intersection than ACL(PT), suggesting that surgery enhanced stability, although rotational stability may remain reduced. More anterior A-P intersection and greater inclination between the FHA and the knee flexion-extension axis best revealed reduced dynamic stability similar to 23 years post-injury.

  • 22.
    Hager, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Changes in sensorimotor behaviour with pain and how to capture these in a movement analysis laboratory2012In: Rheumatology, ISSN 1462-0324, E-ISSN 1462-0332, Vol. 51, p. 14-15Article in journal (Other academic)
  • 23.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Förbättrad klinisk bedömning och behandling med stöd av instrumentell rörelseanalys2013Conference paper (Refereed)
  • 24.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    How may various movment laboratory techniques be used to increase the understanding of human sensorimotor control and address questions of clinical relevance?2012Conference paper (Refereed)
  • 25.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Human sensorimotor control and nerve-muscle function as approached in movement analysis laboratories2012Conference paper (Refereed)
  • 26.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Laboratory based movement analysis to study human sensorimotor control.2012Conference paper (Refereed)
  • 27.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Long term consequences after rupture of the anterior cruciate ligament2013Conference paper (Refereed)
  • 28.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Motor control aspects in rehabilitation of knee disorders2014Conference paper (Refereed)
  • 29.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Revised version of a comprehensive hand book for gait analysis2012In: Advances in Physiotherapy, ISSN 1403-8196, E-ISSN 1651-1948, Vol. 14, no 3, p. 140-140Article, book review (Other academic)
  • 30.
    Häger Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    To grip and not to slip: sensorimotor mechanisms in reactive control of grasp stability1995Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The reactive control of fingertip forces maintaining grasp stability was examined in man during a prehensile task. Blindfolded subjects used the precision grip between the tips of index finger and thumb to restrain an object that was subjected to unpredictable load forces. These were delivered tangential to the parallel grip surfaces of the object. Load forces, grip forces (perpendicular to the grip surfaces) and position of the object were recorded.Subjects automatically adjusted the grip forces to loads of various amplitudes and rates. Thereby they maintained a reliable safety margin against frictional slips without using excessive grip forces. A rapid rise in grip force lasting about 0.2 s was triggered after a short delay following the onset of a sustained ramp load increase. This 'catch-up' response caused a quick restoration of an adequate grip:load force ratio that prevented frictional slips. If the ramp load continued to increase after the catchup response, the grip force also increased in parallel with the load change in a 'tracking' manner. Consequently, during the hold phases of 'ramp-and-hold' loads, the employed grip forces were approximately proportional to the load amplitude. Sensory information about the rate of change of the load force parametrically scaled the 'catchup' and 'tracking' responses.Following anesthetic block of sensory input from the digits, the grip responses were both delayed and attenuated or even abolished. To compensate for these impairments, subjects had to voluntarily maintain exceedingly high grip forces to prevent the object from slipping. The grip control improved slightly during hand and forearm support conditions that allowed marked wrist movements to occur in response to the loading. This indicates that signals from receptors in muscles, joints or skin areas proximal to the digits can to some extent be used to adjust grip forces during impaired digital sensibility. In contrast, these signals had only minor influence on the control during normal digital sensibility.Grip responses to loads delivered in various directions revealed that the load direction, in relation to gravity and to the hand's geometry, represents intrinsic task variables in the automatic processes that maintain a stable grasp. The load direction influenced both the response latencies and the magnitudes of the grip responses. The response latencies were shortest for loads in directions that were the most critical with regard to the consequences of frictional slippage, i.e., loads directed away from the palm or in the direction of gravity. Recordings of signals in cutaneous afferents innervating the finger tips demonstrated that these effects on the response latencies depended on differences in the time needed by the central nervous system to implement the motor responses. The short latencies in the most ‘criticar load directions may reflect the preparation of a default response, while additional central processing would be needed to execute the response to loads in other directions. Adjustments to local frictional anisotropies at the digit-object interface largely explained the magnitude effects.In conclusion, grip responses are automatically adjusted to the current loading condition during unpredictable loading of a hand held object. Subjects call up a previously acquired sensorimotor transform that supports grasp stability by preventing both object slippage and excessive grip forces. Cutaneous sensory information about tangential forces and frictional conditions at the digit-object interface is used to initiate and scale the grip responses to the current loading conditions, largely in a predictive manner.

  • 31.
    Häger-Ross, Charlotte
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Cole, KJ
    Johansson, Roland S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Grip-force responses to unanticipated object loading: load direction reveals body- and gravity-referenced intrinsic task variables1996In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 110, no 1, p. 142-150Article in journal (Refereed)
    Abstract [en]

    Humans preserve grasp stability by automatically regulating the grip forces when loads are applied tangentially to the grip surfaces of a manipulandum held in a precision grip. The effects of the direction of the load force in relation to the palm, trunk, and gravity were investigated in blindfolded subjects. Controlled, tangential load-forces were delivered in an unpredictable manner to the grip surface in contact with the index finger either in the distal and proximal directions (away from and toward the palm) or in the ulnar and radial directions (transverse to the palm). The hand was oriented in: (1) a standard position, with the forearm extended horizontally and anteriorly in intermediate pronosupination; (2) an inverted position, reversing the direction of radial and ulnar loads in relation to gravity; and (3) a horizontally rotated position, in which distal loads were directed toward the trunk. The amplitude of the grip-force responses (perpendicular to the grip surface) varied with the direction of load in a manner reflecting frictional anisotropies at the digit-object interface; that is, the subjects automatically scaled the grip responses to provide similar safety margins against frictional slips. For all hand positions, the time from onset of load increase to start of the grip-force increase was shorter for distal loads, which tended to pull the object out of the hand, than for proximal loads. Furthermore, this latency was shorter for loads in the direction of gravity, regardless of hand position. Thus, shorter latencies were observed when frictional forces alone opposed the load, while longer latencies occurred when gravity also opposed the load or when the more proximal parts of the digits and palm were positioned in the path of the load. These latency effects were due to different processing delays in the central nervous system and may reflect the preparation of a default response in certain critical directions. The response to loads in other directions would incur delays required to implement a new frictional scaling and a different muscle activation pattern to counteract the load forces. We conclude that load direction, referenced to gravity and to the hand's geometry, represents intrinsic task variables in the automatic processes that maintain a stable grasp on objects subjected to unpredictable load forces. In contrast, the grip-force safety margin against frictional slips did not vary systematically with respect to these task variables. Instead, the magnitude of the grip-force responses varied across load direction and hand orientation according to frictional differences providing similar safety margins supporting grasp stability.

  • 32.
    Häger-Ross, Charlotte
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Johansson, Roland S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Nondigital afferent input in reactive control of fingertip forces during precision grip1996In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 110, no 1, p. 131-141Article in journal (Refereed)
    Abstract [en]

    Sensory inputs from the digits are important in initiating and scaling automatic reactive grip responses that help prevent frictional slips when grasped objects are subjected to destabilizing load forces. In the present study we analyzed the contribution to grip-force control from mechanoreceptors located proximal to the digits when subjects held a small manipulandum between the tips of the thumb and index finger. Loads of various controlled amplitudes and rates were delivered tangential to the grip surfaces at unpredictable times. Grip forces (normal to the grip surfaces) and the position of the manipulandum were recorded. In addition, movements of hand and arm segments were assessed by recording the position of markers placed at critical points. Subjects performed test series during normal digital sensibility and during local anesthesia of the index finger and thumb. To grade the size of movements of tissues proximal to the digits caused by the loadings, three different conditions of arm and hand support were used; (1) in the hand-support condition the subjects used the three ulnar fingers to grasp a vertical dowel support and the forearm was supported in a vacuum cast; (2) in the forearm-support condition only the forearm was supported; finally, (3) in the no-support condition the arm was free. With normal digital sensibility the size of the movements proximal to the digits had small effects on the grip-force control. In contrast, the grip control was markedly influenced by the extent of such movements during digital anesthesia. The poorest control was observed in the hand-support condition, allowing essentially only digital movements. The grip responses were either absent or attenuated, with greatly prolonged onset latencies. In the forearm and no-support conditions, when marked wrist movements took place, both the frequency and the strength of grip-force responses were higher, and the grip response latencies were shorter. However, the performance never approached normal. It is concluded that sensory inputs from the digits are dominant in reactive grip control. However, nondigital sensory input may be used for some grip control during impaired digital sensibility. Furthermore, the quality of the control during impaired sensibility depends on the extent of movements evoked by the load in the distal, unanesthetized parts of the arm. The origin of these useful sensory signals is discussed.

  • 33.
    Häger-Ross, Charlotte
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Klein, C S
    Thomas, C K
    Twitch and tetanic properties of human thenar motor units paralyzed by chronic spinal cord injury.2006In: Journal of neurophysiology, ISSN 0022-3077, Vol. 96, no 1, p. 165-74Article in journal (Refereed)
  • 34.
    Häger-Ross, Charlotte
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Rösblad, Birgit
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Norms for grip strength in children aged 4-16 years2002In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 91, no 6, p. 617-625Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to provide norms for grip strength in children. A total of 530 Swedish 4-16-y-olds was tested with the instrument Grippit. The instrument estimates peak grip strength over a 10s period, and sustained grip strength averaged across the 10s. The increase in grip strength with age was approximately parallel for boys and girls until 10 y of age, after which boys were significantly stronger than girls. Strong correlations existed between grip strength and the anthropometric measures weight, height and, in particular, hand length. Right-handed children were significantly stronger in their dominant hand, while left-handers did not show any strength difference between the hands. It is therefore suggested that when evaluating grip strength in left-handed children both hands should be assumed to be about equally strong, while right-handed children are expected to be up to 10% stronger with their right hand. Sustained grip strength was consistently about 80-85% of peak grip strength, with somewhat lower values in younger children. The present normative data for peak grip strength were slightly lower than 1980s' data from the USA and Australia, probably because of divergences in age grouping and in instruments used. CONCLUSION: Norms for grip strength including estimates of variation were provided for children aged 4-16 y. These data will enable therapists and physicians to compare a patient's score with the scores of normally developed children according to age, gender, handedness and body measures.

  • 35.
    Häger-Ross, Charlotte
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Schieber, M H
    Quantifying the independence of human finger movements: comparisons of digits, hands, and movement frequencies.2000In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 20, no 22, p. 8542-50Article in journal (Refereed)
    Abstract [en]

    To determine whether other digits move when normal humans attempt to move just one digit, we asked 10 right-handed subjects to move one finger at a time while we recorded the motion of all five digits simultaneously with both a video motion analysis system and an instrumented glove. We quantified the independence of the digits to compare (1) the different digits, (2) the right versus the left hand, and (3) movements at a self-paced frequency versus externally paced movements at 3 Hz. We also quantified the degree to which motion occurred at the proximal, middle, or distal joint of each digit. Even when asked to move just one finger, normal human subjects produced motion in other digits. Movements of the thumb, index finger, and little finger typically were more highly individuated than were movements of the middle or ring fingers. Fingers of the dominant hand were not more independent than were those of the nondominant hand. Self-paced movements made at approximately 2 Hz were more highly individuated than were externally paced movements at 3 Hz. Angular motion tended to be greatest at the middle joint of each digit, with increased angular motion at the proximal and distal joints during 3 Hz movements. Simultaneous motion of noninstructed digits may result in part from passive mechanical connections between the digits, in part from the organization of multitendoned finger muscles, and in part from distributed neural control of the hand.

  • 36.
    Häger-Ross, Charlotte
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Sundelin, Gunnevi
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Physiotherapy Education in Sweden2007In: Physsical Therapy Reviews, ISSN 1083-3196, Vol. 12, no 2, p. 139-144Article in journal (Refereed)
  • 37. Hébert-Losier, Kim
    et al.
    Pini, Alessia
    Vantini, Simone
    Strandberg, Johan
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Abramowicz, Konrad
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Schelin, Lina
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    One-leg hop kinematics 20years following anterior cruciate ligament rupture: Data revisited using functional data analysis2015In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 30, no 10, p. 1153-1161Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Despite interventions, anterior cruciate ligament ruptures can cause long-term deficits. To assist in identifying and treating deficiencies, 3D-motion analysis is used for objectivizing data. Conventional statistics are commonly employed to analyze kinematics, reducing continuous data series to discrete variables. Conversely, functional data analysis considers the entire data series.

    METHODS: Here, we employ functional data analysis to examine and compare the entire time-domain of knee-kinematic curves from one-leg hops between and within three groups. All subjects (n=95) were part of a long-term follow-up study involving anterior cruciate ligament ruptures treated ~20years ago conservatively with physiotherapy only or with reconstructive surgery and physiotherapy, and matched knee-healthy controls.

    FINDINGS: Between-group differences (injured leg, treated groups; non-dominant leg, controls) were identified during the take-off and landing phases, and in the sagittal (flexion/extension) rather than coronal (abduction/adduction) and transverse (internal/external) planes. Overall, surgical and control groups demonstrated comparable knee-kinematic curves. However, compared to controls, the physiotherapy-only group exhibited less flexion during the take-off (0-55% of the normalized phase) and landing (44-73%) phase. Between-leg differences were absent in controls and the surgically treated group, but observed during the flight (4-22%, injured leg>flexion) and the landing (57-85%, injured leg<internal rotation) phases in the physiotherapy-only group.

    INTERPRETATION: Functional data analysis identified specific functional knee-joint deviations from controls persisting 20years post anterior cruciate ligament rupture, especially when treated conservatively. This approach is suggested as a means for comprehensively analyzing complex movements, adding to previous analyses.

  • 38. Hébert-Losier, Kim
    et al.
    Schelin, Lina
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Tengman, Eva
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Strong, Andrew
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Curve analyses reveal altered knee, hip, and trunk kinematics during drop-jumps long after anterior cruciate ligament rupture2018In: Knee (Oxford), ISSN 0968-0160, E-ISSN 1873-5800, Vol. 25, no 2, p. 226-239Article in journal (Refereed)
    Abstract [en]

    Background: Anterior cruciate ligament (ACL) ruptures may lead to knee dysfunctions later in life. Single-leg tasks are often evaluated, but bilateral movements may also be compromised. Our aim was to use curve analyses to examine double-leg drop–jump kinematics in ACL-reconstructed, ACL-deficient, and healthy-knee cohorts.

    Methods: Subjects with unilateral ACL ruptures treated more than two decades ago (17–28 years) conservatively with physiotherapy (ACLPT, n = 26) or in combination with reconstructive surgery (ACLR, n = 28) and healthy-knee controls (n = 25) performed 40-cm drop–jumps. Three-dimensional knee, hip, and trunk kinematics were analyzed during Rebound, Flight, and Landing phases. Curves were time-normalized and compared between groups (injured and non-injured legs of ACLPT and ACLR vs. non-dominant and dominant legs of controls) and within groups (between legs) using functional analysis of variance methods.

    Results: Compared to controls, ACL groups exhibited less knee and hip flexion on both legs during Rebound and greater knee external rotation on their injured leg at the start of Rebound and Landing. ACLR also showed less trunk flexion during Rebound. Between-leg differences were observed in ACLR only, with the injured leg more internally rotated at the hip. Overall, kinematic curves were similar between ACLR and ACLPT. However, compared to controls, deviations spanned a greater proportion of the drop–jump movement at the hip in ACLR and at the knee in ACLPT.

    Conclusions: Trunk and bilateral leg kinematics during double-leg drop–jumps are still compromised long after ACL-rupture care, independent of treatment. Curve analyses indicate the presence of distinct compensatory mechanisms in ACLPT and ACLR compared to controls.

  • 39.
    Johansson, Anna-Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Strong, Andrew
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Selling, Jonas
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Rönnqvist, Louise
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Boraxbekk, Carl-Johan
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Social Sciences, Demographic Data Base.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Finger movement control and associated brain activity responses post-stroke2016In: XXI ISEK Congress, 2016Conference paper (Refereed)
    Abstract [en]

    BACKGROUND AND AIM: Impaired finger dexterity is common after stroke, often affecting activities of daily living. Knowledge of kinematic characteristics and of underlying neurological mechanisms of such impairments is important to understand functional recovery. This study aims to investigate finger movement control and related brain activity patterns post-stroke (PS). METHODS: Data from a subsample including 9 participants PS with residual hemiparesis affecting manual dexterity (M age- 66; 3 female) and 12 able-bodied control (C) participants (M age- 65; 3 female) were analyzed. Two series of self-paced cyclic finger extension-flexion movements in random order were performed for each hand (4 series with vision, V, and 4 without vision, NV). Optoelectronic cameras monitored the 3D movement of markers affixed to the fingertips. Motion data was used to calculate each finger's individuation index (II), reflecting movement independence, each finger's Stationarity index (SI), reflecting the ability to keep the finger still while another moves [1] and Movement frequency (MF). Functional magnetic resonance imaging, with simultaneous movement recording, was used to investigate brain activity patterns in relation to the kinematic parameters. II, SI, MF and the effect of vision were analyzed for the 4th digit. RESULTS: A factorial ANOVA 2 [group] x 2 [condition] x 2 [side] x [index type] showed an effect for group (p < .0001; PS < C); condition (p < .01; NV < V); side (p < .0001; affected/non-preferred < non-affected/preferred); and index type (p < .0001; SI < II). An interaction between group and side (p < .01) showed that indices of the affected side were lower compared to the non-affected side within the PS group and compared to both sides in the C group. No significant effects were apparent for MF but significant correlations were found between the indices and MF that were restricted to the PS group alone (over all conditions- r = -0.22; p < .01; within the NV condition- r = -0.19; p < .01; within the affected side r = -0.15; p < .05; and within the SI categorization r = -0.14; p < .05). Furthermore, within NV for the non-affected hand on the SI alone (r = -0.54; p < .05). All indicate that slower movements had higher indices. DISCUSSION: The associations between slower MF and higher index values within the PS group were located to conditions with increased difficulty (NV, affected side, and SI). Thus, reducing speed may be a selected strategy to increase control of finger movements PS when the demand on motor control is high. Further, with the applied calculation of finger movement independence we were able detect group differences, side differences within the PS group, and a positive effect of vision of the hands during performance. This indicates that this calculation is a sensitive measure that could be used to study the effects of stroke and to monitor progression in motor recovery. [1] Häger-Ross & Schieber, 2000, J Neurosci 20:8542-50

  • 40.
    Johansson, Anna-Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Strong, Andrew
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Selling, Jonas
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Rönnqvist, Louise
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Boraxbekk, Carl-Johan
    Umeå University, Faculty of Social Sciences, Demographic Data Base.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Three dimensional kinematic analyses of movement control of individual fingers post-stroke2015In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 42, no Supplement 1, p. S33-S33Article in journal (Refereed)
    Abstract [en]

    Research question: Objectives of the present study are: (1) to quantify finger movements in a 3D context and (2) by this method investigate the ability to perform individualized finger movements, with and without vision of the hands, in persons with a chronic stroke diagnosis compared to able-bodied controls.

    Introduction: Increased knowledge of how fine movement control is affected by stroke is important for the understanding of recovery of function. This is crucial for the development of reliable and valid assessment methods for evaluation of rehabilitation of the upper limbs. This study is part of the MOST project (MOST-MOvement control in STroke) where both clinical tests and 3D movement assessments are performed.

    Materials and methods: At present, 18 persons post-stroke (M age = 67 years; 6 women) and 26 able-bodied controls (M age = 62 years, 11 women) have participated. The ability to perform uni-manual individualized finger movements and the effect of vison of the hands were evaluated. Participants were instructed to move a specific finger in cyclic extension–flexion movements at the metacarpophalangeal joint, keeping the rest of the finger straight and the other fingers still, at a self-paced speed during 10 s (2 test series for each hand; 8 test series in total). The task was performed seated. The wrists were extended about 10° and fixated to a wooden frame with forearm support. Reflective markers were affixed to each fingertip and movements were recorded by optoelectronic cameras. Based on the positional change of the fingers during task performance, two indices ranging from 0-1 were calculated: (1) Individuation index (II) where the independence of each finger movement is shown and where 1 indicate complete independence, (2) stationary index (SI) where 1 indicate that the finger remains still when the other fingers move [1].

    Results: Our results show that it is possible to quantify individual finger movements by use of 3D movement analysis addressing the quality of movement performance in stroke survivors: all but 3 persons post-stroke were able to perform the task. Preliminary analyses (based on a subsample constituted of 8 post-stroke and 8 controls) verify that the test discriminated between groups where participants post-stroke had lower values on II and SI as compared to the control persons, the lowest values were observed for the middle and ring fingers. Ongoing analyses will show if vision influences the outcomes.

    Discussion: A set-up has been tested where individual finger movements can be quantified in 3D, and that discriminates between persons post stroke compared to controls. This advancement carries a promise for development of better assessment methods for recovery of function post-stroke.

    Reference

    [1] C. Häger-Ross, M.H. Schieber Quantifying the independence of human finger movements: comparisons of digits, hands and movement frequencies.J Neurosci, 20 (2000), pp. 8542–8550

     

     

  • 41. Johansson, G. M.
    et al.
    Grip, H.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Introducing a standardized Nine Hole Peg Test in persons with stroke: kinematic analysis2014Conference paper (Refereed)
  • 42.
    Johansson, Gudrun
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Frykberg, G
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    The Arm Posture Score with additional rotational components (APS6) applied to persons with stroke to assess arm movements during gait.2012Conference paper (Refereed)
  • 43.
    Johansson, Gudrun M.
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Frykberg, Gunilla E.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Broström, Eva W
    Department of Women's and Children's Health, Karolinska Institutet.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Assessment of arm movements during gait in stroke: the Arm Posture Score2014In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 40, no 4, p. 549-555Article in journal (Refereed)
    Abstract [en]

    The purpose of the study was to apply the Arm Posture Score (APS) to a stroke population, since comprehensive measures to quantify arm swing in the affected and non-affected arms during gait are lacking. A further aim was to investigate how gait speed and upper limb function estimated by clinical measures are related to the APS in the stroke group. The APS is the summarized root mean square deviation (RMSD) from normal, based on kinematics. Four arm movements (sagittal and frontal planes) as well as six arm movements (incorporating transversal plane) were included in the calculation of APS, referred to as APS4 and APS6, respectively. The study population consisted of 25 persons with stroke and 25 age- and gender-matched controls. The APS measures were significantly different between the affected and non-affected arms, as well as between the affected arm and the non-dominant arm of the controls (p≤0.001). Spasticity significantly influenced both APS measures, while speed only had a significant effect on the APS4. The APS measures correlated significantly to clinical measures of upper limb function. Both APS measures seem to be useful indices to quantify and discriminate between impaired and normal arm swing during gait after stroke. The variability of rotational arm movements needs to be studied further before considering the additional value of the APS6 over the APS4. When interpreting the APS, complementary kinematics should be taken into account, as the single value of the APS gives no information about the direction of the deviation.

  • 44.
    Johansson, Gudrun M.
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Levin, Mindy F
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    The added value of kinematic evaluation of the timed finger-to-nose test in persons post-stroke.2017In: Journal of NeuroEngineering and Rehabilitation, ISSN 1743-0003, E-ISSN 1743-0003, Vol. 14, article id 11Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Upper limb coordination in persons post-stroke may be estimated by the commonly used Finger-to-Nose Test (FNT), which is also part of the Fugl-Meyer Assessment. The total movement time (TMT) is used as a clinical outcome measure, while kinematic evaluation also enables an objective quantification of movement quality and motor performance. Our aims were to kinematically characterize FNT performance in persons post-stroke and controls and to investigate the construct validity of the test in persons with varying levels of impairment post-stroke.

    METHODS: A three-dimensional motion capture system recorded body movements during performance of the FNT in 33 persons post-stroke who had mild or moderate upper limb motor impairments (Fugl-Meyer scores of 50-62 or 32-49, respectively), and 41 non-disabled controls. TMT and kinematic variables of the hand (pointing time, peak speed, time to peak speed, number of movement units, path ratio, and pointing accuracy), elbow/shoulder joints (range of motion, interjoint coordination), and scapular/trunk movement were calculated. Our analysis focused on the pointing phase (knee to nose movement of the FNT). Independent t or Mann-Whitney U tests and effect sizes were used to analyze group differences. Sub-group analyses based on movement time and stroke severity were performed. Within the stroke group, simple and multiple linear regression were used to identify relationships between TMT to kinematic variables.

    RESULTS: The stroke group had significant slower TMT (mean difference 2.6 s, d = 1.33) than the control group, and six other kinematic variables showed significant group differences. At matched speeds, the stroke group had lower accuracy and excessive scapular and trunk movements compared to controls. Pointing time and elbow flexion during the pointing phase were most related to stroke severity. For the stroke group, the number of movement units during the pointing phase showed the strongest association with the TMT, and explained 60% of the TMT variance.

    CONCLUSIONS: The timed FNT discriminates between persons with mild and moderate upper limb impairments. However, kinematic analysis to address construct validity highlights differences in pointing movement post-stroke that are not captured in the timed FNT.

  • 45.
    Johansson, Gudrun M.
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Häger, Charlotte K.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Measurement properties of the motor evaluation scale for upper extremity in stroke patients (MESUPES)2012In: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 34, no 4, p. 288-294Article in journal (Refereed)
    Abstract [en]

    Purpose: To investigate inter-rater reliability of the Motor Evaluation Scale for Upper Extremity in Stroke patients (MESUPES), to provide estimates of the minimal detectable change (MDC) of the MESUPES and to investigate concurrent validity in relation to the arm scores of the Modified Motor Assessment Scale (M MAS). Methods: Forty-two stroke patients (mean age 56 +/- 12 years) were independently assessed within a 48-hours window by two raters in different pairs (total available raters = 4). Results: Weighted. analysis indicated good to very good agreement at item level (range 0.63-0.96). The relative and absolute reliability of the total score of MESUPES (maximum 58) was high according to the intraclass correlation coefficients (ICC = 0.98) and the standard error of measurement (SEM = 2.68). The MDC for three levels of confidence was calculated: A score change of 8, 7 and 5 is necessary for a MDC to have confidence of 95%, 90% and 80%, respectively, of a genuine change. Correlation between the MESUPES and M MAS was high (r(s) = 0.87). Conclusions: The MESUPES shows high inter-rater reliability, and our study provides useful estimates of MDC for different levels of certainty. Additional research to confirm concurrent validity and to examine other psychometric properties of the MESUPES such as sensitivity is needed.

  • 46.
    Johansson, Roland S
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Riso, Ronald
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Somatosensory control of precision grip during unpredictable pulling loads. II. Changes in load force rate.1992In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 89, no 1, p. 192-203Article in journal (Refereed)
    Abstract [en]

    In the previous paper regarding the somatosensory control of the human precision grip, we concluded that the elicited automatic grip force adjustments are graded by the amplitude of the imposed loads when restraining an 'active' object subjected to unpredictable pulling forces (Johansson et al. 1992a). Using the same subjects and apparatus, the present study examines the capacity to respond to imposed load forces applied at various rates. Grip and load forces (forces normal and tangential to the grip surfaces) and the position of the object in the pulling direction (distal) were recorded. Trapezoidal load force profiles with plateau amplitudes of 2 N were delivered at the following rates of loading and unloading in an unpredictable sequence: 2 N/s, 4 N/s or 8 N/s. In addition, trials with higher load rate (32 N/s) at a low amplitude (0.7 N) were intermingled. The latencies between the start of the loading and the onset of the grip force response increased with decreasing load force rate. They were 80 +/- 9 ms, 108 +/- 13 ms, 138 +/- 27 ms and 174 +/- 39 ms for the 32, 8, 4 and 2 N/s rates, respectively. These data suggested that the grip response was elicited after a given minimum latency once a load amplitude threshold was exceeded. The amplitude of the initial rapid increase of grip force (i.e., the 'catch-up' response) was scaled by the rate of the load force, whereas its time course was similar for all load rates. This response was thus elicited as a unit, but its amplitude was graded by afferent information about the load rate arising very early during the loading. The scaling of the catch-up response was purposeful since it facilitated a rapid reconciliation of the ratio between the grip and load force to prevent slips. In that sense it apparently also compensated for the varying delays between the loading phase and the resultant grip force responses. However, modification of the catch-up response may occur during its course when the loading rate is altered prior to the grip force response or very early during the catch-up response itself. Hence, afferent information may be utilized continuously in updating the response although its motor expression may be confined to certain time contingencies. Moreover, this updating may take place after an extremely short latency (45-50 ms).

  • 47.
    Johansson, Roland S
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Riso, Ronald
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Bäckström, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Somatosensory control of precision grip during unpredictable pulling loads. I. Changes in load force amplitude.1992In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 89, no 1, p. 181-191Article in journal (Refereed)
    Abstract [en]

    In manipulating 'passive' objects, for which the physical properties are stable and therefore predictable, information essential for the adaptation of the motor output to the properties of the current object is principally based on 'anticipatory parameter control' using sensorimotor memories, i.e., an internal representation of the object's properties based on previous manipulative experiences. Somatosensory afferent signals only intervene intermittently according to an 'event driven' control policy. The present study is the first in a series concerning the control of precision grip when manipulating 'active' objects that exert unpredictable forces which cannot be adequately represented in a sensorimotor memory. Consequently, the manipulation may be more reliant on a moment-to-moment sensory control. Subjects who were prevented from seeing the hand used the precision grip to restrain a manipulandum with two parallel grip surfaces attached to a force motor which produced distally directed (pulling) loads tangential to the finger tips. The trapezoidal load profiles consisted of a loading phase (4 N/s), plateau phase and an unloading phase (4 N/s) returning the load force to zero. Three force amplitudes were delivered in an unpredictable sequence; 1 N, 2 N and 4 N. In addition, trials with higher load rate (32 N/s) at a low amplitude (0.7 N), were superimposed on various background loads. The movement of the manipulandum, the load forces and grip forces (normal to the grip surfaces) were recorded at each finger. The grip force automatically changed with the load force during the loading and unloading phases. However, the grip responses were initiated after a brief delay. The response to the loading phase was characterized by an initial fast force increase termed the 'catch-up' response, which apparently compensated for the response delay--the grip force adequately matched the current load demands by the end of the catch-up response. In ramps with longer lasting loading phases (amplitude greater than or equal to 2 N) the catch-up response was followed by a 'tracking' response, during which the grip force increased in parallel with load force and maintained an approximately constant force ratio that prevented frictional slips. The grip force during the hold phase was linearly related to the load force, with an intercept close to the grip force used prior to the loading. Likewise, the grip force responses evoked by the fast loadings superimposed on existing loads followed the same linear relationship.(ABSTRACT TRUNCATED AT 400 WORDS)

  • 48. Klein, C S
    et al.
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Thomas, C K
    Fatigue properties of human thenar motor units paralysed by chronic spinal cord injury.2006In: The Journal of physiology, ISSN 0022-3751, Vol. 573, no Pt 1, p. 161-71Article in journal (Refereed)
  • 49.
    Lämås, Kristina
    et al.
    Umeå University, Faculty of Medicine, Department of Nursing.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Lindgren, Lenita
    Umeå University, Faculty of Medicine, Department of Nursing. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Wester, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Brulin, Christine
    Umeå University, Faculty of Medicine, Department of Nursing.
    Does touch massage facilitate recovery after stroke?: A study protocol of a randomized controlled trial2016In: BMC Complementary and Alternative Medicine, ISSN 1472-6882, E-ISSN 1472-6882, Vol. 16, article id 50Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Despite high quality stroke care, decreased sensorimotor function, anxiety and pain often remain one year after stroke which can lead to impaired health and dependence, as well as higher healthcare costs. Touch massage (TM) has been proven to decrease anxiety and pain, and improve quality of health in other conditions of reduced health, where reduced anxiety seems to be the most pronounced benefit. Thus there are reasons to believe that TM may also reduce anxiety and pain, and improve quality of life after stroke. Further, several studies indicate that somatosensory stimulation can increase sensorimotor function, and it seems feasible to believe that TM could increase independence after stroke. In this study we will evaluate effects of TM after stroke compared to sham treatment.

    METHODS: This is a prospective randomized open-labelled control trial with blinded evaluation (PROBE-design). Fifty patients with stroke admitted to stroke units will be randomized (1:1) to either a TM intervention or a non-active transcutaneous electrical nerve stimulation (non-TENS) control group. Ten sessions of 30 min treatments (TM or control) will be administered during two weeks. Assessment of status according to the International Classification of Functioning, Disability and Health (ICF), including body function, activity, and participation. Assessment of body function will include anxiety, pain, and stress response (heart rate variability and salivary cortisol), where anxiety is the primary outcome. Activity will be assessed by means of sensorimotor function and disability, and participation by means of health-related quality of life. Assessments will be made at baseline, after one week of treatment, after two weeks of treatment, and finally a follow-up after two months. The trial has been approved by the Regional Ethical Review Board.

    DISCUSSION: TM seems to decrease anxiety and pain, increase health-related quality of life, and improve sensorimotor functions after stroke, but the field is largely unexplored. Considering the documented pleasant effects of massage in general, absence of reported adverse effects, and potential effects in relation to stroke, it is essential to evaluate effects of TM during the sub-acute phase after stroke. The results of this project will hopefully provide important knowledge for evidence-based care.

    TRIAL REGISTRATION: ClinicalTrials.gov: NTC01883947.

  • 50.
    Macefield, Vaughan G
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Johansson, Roland S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Control of grip force during restraint of an object held between finger and thumb: responses of cutaneous afferents from the digits1996In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 108, no 1, p. 155-171Article in journal (Refereed)
    Abstract [en]

    Unexpected pulling and pushing loads exerted by an object held with a precision grip evoke automatic and graded increases in the grip force (normal to the grip surfaces) that prevent escape of the object; unloading elicits a decrease in grip force. Anesthesia of the digital nerves has shown that these grip reactions depend on sensory signals from the digits. In the present study we assessed the capacity of tactile afferents from the digits to trigger and scale the evoked grip responses. Using tungsten microelectrodes inserted percutaneously into the median nerve of awake human subjects, unitary recordings were made from ten FA I and 13 FA II rapidly adapting afferents, and 12 SA I and 18 SA II slowly adapting afferents. While the subject held a manipulandum between a finger and the thumb, tangential load forces were applied to the receptor-bearing digit (index, middle, or ring finger or thumb) as trapezoidal load-force profiles with a plateau amplitude of 0.5-2.0 N and rates of loading and unloading at 2-8 N/s, or as "step-loads" of 0.5 N delivered at 32 N/s. Such load trials were delivered in both the distal (pulling) and proximal (pushing) direction. FA I afferents responded consistently to the load forces, being recruited during the loading and unloading phases. During the loading ramp the ensemble discharge of the FA I afferents reflected the first time-derivative of the load force (i.e., the load-force rate). These afferents were relatively insensitive to the subject's grip force responses. However, high static finger forces appeared to suppress excitation of these afferents during the unloading phase. The FA II afferents were largely insensitive to the load trials: only with the step-loads did some afferents respond. Both classes of SA afferents were sensitive to load force and grip force, and discharge rates were graded by the rate of loading. The firing of the SA I afferents appeared to be relatively more influenced by the subject's grip-force response than the discharge of the SA II afferents, which were more influenced by the load-force stimulus. The direction in which the tangential load force was applied to the skin influenced the firing of most afferents and in particular the SA II afferents. Individual afferents within each class (except for the FA IIs) responded to the loading ramp before the onset of the subject's grip response and may thus be responsible for initiating the automatic increase in grip force. However, nearly half of the FA I afferents recruited by the load trials responded to the loading phase early enough to trigger the subject's grip-force response, whereas only ca. one-fifth of the SA Is and SA IIs did so. These observations, together with the high density of FA I receptors in the digits, might place the FA I afferents in a unique position to convey the information required to initiate and scale the reactive grip-force responses to the imposed load forces.

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