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  • 1.
    Bergman, Frida
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Mattson-Frost, Tove
    Jonasson, Lars
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Chorell, Elin
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Sörlin, Ann
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Wennberg, Patrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Ryberg, Mats
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Levine, James
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Boraxbekk, Carl-Johan
    Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Installing treadmill workstations in offices does little for cognitive performance and brain structure, despite a baseline association between sitting time and hippocampus volumeManuscript (preprint) (Other academic)
  • 2.
    Bergman, Frida
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Wahlström, Viktoria
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Stomby, Andreas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Otten, Julia
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Lanthén, Ellen
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Renklint, Rebecka
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Waling, Maria
    Umeå University, Faculty of Social Sciences, Department of Food and Nutrition.
    Sörlin, Ann
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Boraxbekk, Carl-Johan
    Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR). Danish Research Center for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark.
    Wennberg, Patrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Levine, James A.
    Department of Endocrinology, The Mayo Clinic, Rochester, MN, USA; Fondation IPSEN, Paris, France.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Treadmill workstations in office workers who are overweight or obese: a randomised controlled trial2018In: The Lancet Public Health, ISSN 2468-2667, Vol. 3, no 11, article id e523-e535Article in journal (Refereed)
    Abstract [en]

    Background: Treadmill workstations that enable office workers to walk on a treadmill while working at their computers might increase physical activity in offices, but long-term effects are unknown. We therefore investigated whether treadmill workstations in offices increased daily walking time.

    Methods: We did a randomised controlled trial of healthy office workers who were either overweight or obese. We recruited participants from 13 different companies, which comprised 17 offices, in Umeå, Sweden. We included people who were aged 40-67 years, had sedentary work tasks, and had a body-mass index (BMI) between 25 kg/m2 and 40 kg/m2. After the baseline measurement, we stratified participants by their BMI (25-30 kg/m2 and >30 to 40 kg/m2); subsequently, an external statistician randomly assigned these participants (1:1) to either the intervention group (who received treadmill workstations for optional use) or the control group (who continued to work at their sit-stand desks as usual). Participants in the intervention group received reminders in boosting emails sent out to them at four occasions during the study period. Researchers were masked to group assignment until after analysis of the primary outcome. After the baseline measurement, participants were not masked to group belongings. The primary outcome was total daily walking time at weekdays and weekends, measured at baseline, 2 months, 6 months, 10 months, and 13 months with the accelerometer activPAL (PAL Technologies, Glasgow, UK), which was worn on the thigh of participants for 24 h a day for 7 consecutive days. We used an intention-to-treat approach for our analyses. This trial is registered with ClinicalTrials.gov, number NCT01997970, and is closed to new participants.

    Findings: Between Nov 1, 2013, and June 30, 2014, a total of 80 participants were recruited and enrolled (n=40 in both the intervention and control groups). Daily walking time during total time awake at weekdays increased between baseline and 13 months by 18 min (95% CI 9 to 26) in the intervention group and 1 min (-7 to 9) in the control group (difference 22 min [95% CI 7 to 37], pinteraction=0·00045); for weekend walking, the change from baseline to 13 months was 5 min (-8 to 18) in the intervention group and 8 min (-5 to 21) in the control group (difference -1 min [-19 to 17]; pinteraction=0·00045). Neither measure met our predetermined primary outcome of 30 min difference in total walking time between the intervention and control group, so the primary outcome of the trial was not met. One adverse event was reported in a participant who accidently stepped on their Achilles tendon.

    Interpretation: In a sedentary work environment, treadmill workstations result in a statistically significant but smaller-than-expected increase in daily walking time. Future studies need to investigate how increasing physical activity at work might have potentially compensatory effects on non-work activity.

  • 3.
    Bergman, Frida
    et al.
    Umeå University.
    Wahlström, Viktoria
    Umeå University.
    Wennberg, Patrik
    Umeå University.
    Boraxbekk, Carl-Johan
    Umeå University.
    Sörlin, Ann
    Umeå University.
    Öhberg, Fredrik
    Umeå University.
    Olsson, Tommy
    Umeå University.
    Increasing Physical Activity In Office Workers - An RCT Of Treadmill Workstations2018In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 50, no 5, p. 47-47Article in journal (Other academic)
    Abstract [en]

    PURPOSE: Our primary hypothesis was that an intervention with treadmill workstations would increase time spent walking. Secondary hypotheses were a decrease in time spent sitting with a concomitant increase in time spent standing and in light intensity physical activity (LPA) leading to positive effects on body measurements and body composition.

    METHODS: The intervention group received a treadmill workstation at their office desk during 13 months. Daily time spent sitting, standing and walking and number of steps was measured with activPAL®. Daily time in LPA and MVPA was measured with Actigraph®. Body weight, BMI and waist circumference were measured according to standardized protocols. Dual X-ray Absorptiometry was used to estimate body composition. Mixed models was used for the statistical analysis, with group, day of week (weekday/ weekend), time point and gender as fixed effects and age as a covariate. p<0.05 was considered significant.

    RESULTS: Eighty participants were included. The intervention group significantly increased their time spent walking at all follow-ups, with a difference at 13 months of 22 minutes (p<0.01) and 1645 steps per day (p<0.05), respectively, versus controls. Concomitantly, they decreased their MVPA with 13 minutes per day (p<0.001) at weekdays at 13 months versus baseline. We also found a decrease in LPA with 19 minutes per day (p<0.05), and of 17 minutes per day for MVPA (p<0.001) at 13 months versus baseline at weekends. The control group increased their time spent sitting with 25 minutes per day (p<0.05) and decreased the time spent standing with 35 minutes per day at weekdays (p<0.001) compared to baseline. There was also a decrease in LPA with 14 minutes per day (p<0.01) and in MVPA with 6 minutes per day (p<0.01) versus baseline during weekdays, with a decrease in sitting time with 36 minutes (p<0.05) at weekends. There were no significant changes in body measurements or body composition.

    CONCLUSION: It is possible to increase daily walking time by introducing treadmill workstations at offices. A decreased MVPA within the intervention group may contribute to lack of effects on body measurements and body composition. It is therefore important that future interventions aim at both reducing sedentary time as well as increasing, or at least remaining, MVPA levels.

  • 4.
    Bjerke, Joakim
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Department of Physiotherapy, School of Health Education & Social Work, Sør-Trøndelag University College, Trondheim, Norway.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Nilsson, Kjell G
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Orthopaedics.
    Foss, Olav A
    Orthopaedic Research Centre, Trondheim University Hospital, Trondheim, Norway.
    Stensdotter, Ann-Katrin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Department of Physiotherapy, School of Health Education & Social Work, Sør-Trøndelag University College, Trondheim, Norway.
    Peak knee flexion angles during stair descent in TKA patients2014In: The Journal of Arthroplasty, ISSN 0883-5403, E-ISSN 1532-8406, Vol. 29, no 4, p. 707-711Article in journal (Refereed)
    Abstract [en]

    Reduced peak knee flexion during stair descent (PKSD) is demonstrated in subjects with total knee arthroplasty (TKA), but the underlying factors are not well studied. 3D gait patterns during stair descent, peak passive knee flexion (PPKF), quadriceps strength, pain, proprioception, demographics, and anthropometrics were assessed in 23 unilateral TKA-subjects ~ 19 months post-operatively, and in 23 controls. PKSD, PPKF and quadriceps strength were reduced in the TKA-side, but also in the contralateral side. A multiple regression analysis identified PPKF as the only predictor (57%) to explain the relationship with PKSD. PPKF was, however sufficient for normal PKSD. Deficits in quadriceps strength in TKA-group suggest that strength is also contributing to smaller PKSD. Increased hip adduction at PKSD may indicate both compensatory strategy and reduced hip strength.

  • 5.
    Bjerke, Joakim
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Department of Physiotherapy, School of Health Education & Social Work, Sør-Trøndelag University College, Trondheim, Norway.
    Öhberg, Fredrik
    Department of Biomedical Engineering & Informatics, Umeå University Hospital, Umeå, Sweden.
    Nilsson, Kjell G
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Orthopaedics.
    Stensdotter, Ann-Katrin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Department of Physiotherapy, School of Health Education & Social Work, Sør-Trøndelag University College, Trondheim, Norway.
    Compensatory strategies for muscle weakness during stair ascent in subjects with total knee arthroplasty2014In: The Journal of Arthroplasty, ISSN 0883-5403, E-ISSN 1532-8406, Vol. 29, no 7, p. 1499-1502Article in journal (Refereed)
    Abstract [en]

    Subjects with total knee arthroplasty (TKA) exhibit decreased quadriceps and hamstring strength. This may bring about greater relative effort or compensatory strategies to reduce knee joint moments in daily activities. To study gait and map out the resource capacity, knee muscle strength was assessed by maximal voluntary concentric contractions, and whole body kinematics and root mean square (RMS) electromyography (EMG) of vastus lateralis and semitendinosus were recorded during stair ascent in 23 unilateral TKA-subjects ~19months post-operation, and in 23 healthy controls. Muscle strength and gait velocity were lower in the TKA group, but no significant group differences were found in RMS EMG or forward trunk lean. The results suggest that reduced walking velocity sufficiently compensated for reduced knee muscle strength.

  • 6.
    Bjerke, Joakim
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Department of Physiotherapy, School of Health Education & Social Work, Sør-Trøndelag University College, Trondheim, Norway.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Nilsson, Kjell G
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Stensdotter, Ann-Katrin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Department of Physiotherapy, School of Health Education & Social Work, Sør-Trøndelag University College, Trondheim, Norway.
    Gait on soft versus hard surface after total knee arthroplastyManuscript (preprint) (Other academic)
    Abstract [en]

    Asymmetric gait patterns are common following total knee arthroplasty (TKA). Gait on even and hard surface is primarily characterized by reduced peak knee flexion in the prosthetic knee, increased contralateral knee adduction angle, and decreased walking speed compared to controls. Natural conditions may however lead to different strategies. Therefore, the objective of the present study was to explore how gait patterns may differ when walking on a soft surface. Methods: 3D kinematics during gait on hard and soft surface were assessed in 23 unilateral TKA-subjects ~19 months post-operative, and in 23 controls. Results: Gait characteristics in TKA-subjects that differed from controls observed on hard surface were amplified on soft surface. Flexion in the prosthetic knee was further decreased and a tendency towards reduced flexion in the contralateral knee was observed. Knee and hip adduction were not affected by surface conditions nevertheless there was a difference between groups, in particular with regard to the prosthetic side. In addition, step width increased on soft surface in TKA-subjects. Conclusion: Gait on an even and soft surface did not amplify asymmetries in TKA-subjects, but decreased knee flexion and increased step-width, albeit with similar gait speed as the control group suggests that the soft surface provided a small but significant challenge making the TKA-subjects precautious.

  • 7.
    Bjerke, Joakim
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Department of Physiotherapy, Faculty of Health and Social Sciences, Norwegian University of Science and Technology, Trondheim, Norway.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Nilsson, Kjell G
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Orthopaedics.
    Stensdotter, Ann-Katrin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation. epartment of Physiotherapy, Faculty of Health and Social Sciences, Norwegian University of Science and Technology, Trondheim, Norway .
    Walking on a compliant surface does not enhance kinematic gait asymmetries after unilateral total knee arthroplasty2016In: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 24, no 8, p. 2606-2613Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To investigate gait asymmetries and the effect of walking on compliant surfaces in individuals with unilateral total knee arthroplasty (TKA), hypothesizing that asymmetries would increase as an effect of the compliant surface.

    METHODS: Individuals with unilateral TKA ~19 months post-operative (n = 23, median age 59 years) recruited from one orthopaedic clinic and age- and gender-matched healthy individuals without knee complaints (n = 23, median age 56 years) walked at comfortable speed on a hard surface and on a compliant surface. 3D kinematic analyses were made for knee and hip angles in sagittal and frontal planes, stance time, step length, and gait velocity.

    RESULTS: Shorter stance time (p < 0.01) and less peak knee flexion (p < 0.001) at weight bearing acceptance was found in the prosthetic side compared with the contralateral side. Larger knee (p < 0.01) and hip (p < 0.001) adduction was found compared with healthy controls. Neither asymmetries between the prosthetic and the contralateral side nor differences compared with healthy controls were enhanced when walking on compliant surfaces compared with hard surfaces.

    CONCLUSION: The TKA group adapted their gait to compliant surfaces similarly to healthy controls. Gait asymmetries in the TKA group observed on hard surface were not enhanced, and adduction in hip and knee joints did not increase further as an effect of walking on compliant surfaces. Thus, unfavourable knee joint loading did not increase when walking on a compliant surface. This implies that recommendations for walking on soft surfaces to reduce knee joint loading are not counteracted by increased gait asymmetries and unfavourable joint loading configurations.

    LEVEL OF EVIDENCE: III.

  • 8. Ertzgaard, Per
    et al.
    Öhberg, Fredrik
    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).
    Gerdle, Björn
    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).
    A new way of assessing arm function in activity using kinematic Exposure Variation Analysis and portable inertial sensors - A validity study2016In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 21, p. 241-249Article in journal (Refereed)
    Abstract [en]

    Portable motion systems based on inertial motion sensors are promising methods, with the advantage compared to optoelectronic cameras of not being confined to a laboratory setting. A challenge is to develop relevant outcome measures for clinical use. The aim of this study was to characterize elbow and shoulder motion during functional tasks, using portable motion sensors and a modified Exposure Variation Analysis (EVA) and evaluate system accuracy with optoelectronic cameras. Ten healthy volunteers and one participant with sequel after stroke performed standardised functional arm tasks. Motion was registered simultaneously with a custom developed motion sensor system, including gyroscopes and accelerometers, and an optoelectronic camera system. The EVA was applied on elbow and shoulder joints, and angular and angular velocity EVA plots was calculated. The EVA showed characteristic patterns for each arm task in the healthy controls and a distinct difference between the affected and unaffected arm in the participant with sequel after stroke. The accuracy of the portable system was high with a systematic error ranging between -1.2 degrees and 2.0 degrees. The error was direction specific due to a drift component along the gravity vector. Portable motion sensor systems have high potential as clinical tools for evaluation of arm function. EVA effectively illustrates joint angle and joint angle velocity patterns that may capture deficiencies in arm function and movement quality. Next step will be to manage system drift by including magnetometers, to further develop clinically relevant outcome variables and apply this for relevant patient groups.

  • 9.
    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

  • 10.
    Grip, Helena
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Nilsson, Kjell G
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Häger, Charlotte G.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Does the Femoral Head Size in Hip Arthroplasty Influence Lower Body Movements during Squats, Gait and Stair Walking?: A Clinical Pilot Study Based on Wearable Motion Sensors2019In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, no 14, article id 3240Article in journal (Refereed)
    Abstract [en]

    A hip prosthesis design with larger femoral head size may improve functional outcomes compared to the conventional total hip arthroplasty (THA) design. Our aim was to compare the range of motion (RoM) in lower body joints during squats, gait and stair walking using a wearable movement analysis system based on inertial measurement units (IMUs) in three age-matched male groups: 6 males with a conventional THA (THAC), 9 with a large femoral head (LFH) design, and 8 hip- and knee-asymptomatic controls (CTRL). We hypothesized that the LFH design would allow a greater hip RoM, providing movement patterns more like CTRL, and a larger side difference in hip RoM in THAC when compared to LFH and controls. IMUs were attached to the pelvis, thighs and shanks during five trials of squats, gait, and stair ascending/descending performed at self-selected speed. THAC and LFH participants completed the Hip dysfunction and Osteoarthritis Outcome Score (HOOS). The results showed a larger hip RoM during squats in LFH compared to THAC. Side differences in LFH and THAC groups (operated vs. non-operated side) indicated that movement function was not fully recovered in either group, further corroborated by non-maximal mean HOOS scores (LFH: 83 +/- 13, THAC: 84 +/- 19 groups, vs. normal function 100). The IMU system may have the potential to enhance clinical movement evaluations as an adjunct to clinical scales.

  • 11.
    Grip, Helena
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sterner, Ylva
    Karlsson, J Stefan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Gerdle, Björn
    Classification of neck movement patterns related to whiplash-associated disorders using neural networks2003In: IEEE transactions on information technology in biomedicine, ISSN 1089-7771, Vol. 7, no 4, p. 412-418Article in journal (Refereed)
    Abstract [en]

    This paper presents a new method for classification of neck movement patterns related to Whiplash-associated disorders (WAD) using a resilient backpropagation neural network (BPNN). WAD are a common diagnosis after neck trauma, typically caused by rear-end car accidents. Since physical injuries seldom are found with present imaging techniques, the diagnosis can be difficult to make. The active range of the neck is often visually inspected in patients with neck pain, but this is a subjective measure, and a more objective decision support system, that gives a reliable and more detailed analysis of neck movement pattern, is needed. The objective of this study was to evaluate the predictive ability of a BPNN, using neck movement variables as input. Three-dimensional (3-D) neck movement data from 59 subjects with WAD and 56 control subjects were collected with a ProReflex system. Rotation angle and angle velocity were calculated using the instantaneous helical axis method and motion variables were extracted. A principal component analysis was performed in order to reduce data and improve the BPNN performance. BPNNs with six hidden nodes had a predictivity of 0.89, a sensitivity of 0.90 and a specificity of 0.88, which are very promising results. This shows that neck movement analysis combined with a neural network could build the basis of a decision support system for classifying suspected WAD, even though further evaluation of the method is needed.

  • 12.
    Hoshi, Kei
    et al.
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Nyberg, Annakarin
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Bridging the contextual reality gap in blended reality space: the case of AGNES2011In: Include 2011 Proceedings: the role of inclusive design in making social innovation happen, 2011Conference paper (Refereed)
    Abstract [en]

    This research explores where the contextual reality gap emerges in social sharing of knowledge, understanding and experience generated between users (also between a designer and a user) in different contexts. It then examines how this 'contextual reality gap' can be bridged effectively in the sharing of meaning through mediated communication within emergent virtual/physical space, in what we call Blended Reality Space. As a concrete example, we refer to our current project, AGNES, developing User-sensitive Home-based Systems for Successful Ageing in a Networked Society, funded under the Ambient Assisted Living (AAL) Joint programme. Finally, we propose a conceptual framework for managing, structuring and composing contexts in designing interactive systems, a new approach we refer to as the Contextual Reality Framework.

  • 13.
    Hoshi, Kei
    et al.
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Nyberg, Annakarin
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Designing blended reality space: conceptual foundations and applications2011In: The 25th British Computer Society Conference on Human Computer Interaction – HCI2011, 2011Conference paper (Refereed)
    Abstract [en]

    The present paper starts with a crucial discussion about the imbalance between technological and human concerns in the context of human-computer interaction, an imbalance that has arisen partly from the mechanistic aspect and its impact on interaction design. We then introduce the concept of Blended Reality Space, interactive mixed reality environments where the physical and the virtual are seamlessly combined and affect each other. The conceptual grounding and practical examples that illustrate our approach to interaction design are then discussed, adopting a standard figurative representation of blends. This helps understanding the role of blending that meaningfully bridges unbalanced separations between cognition and action, and the physical and the virtual. As a concrete example, the AGNES project, which is aimed at developing “user sensitive home-based systems for successful ageing in a networked society”, is introduced. We believe that the emphasis on ʻbalanceʼ or appropriate blending is very important in the development of better interactive systems for health, capitalizing on seamless combinations of the virtual and the physical in Blended Reality Space.

  • 14. Lindberg, F
    et al.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Brodin, LA
    Grönlund, Christer
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Assessment of intramuscular activation patterns using ultrasound M-mode strain2013In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 23, no 4, p. 879-885Article in journal (Refereed)
    Abstract [en]

    The intramuscular activation pattern can be connected to the motor unit recruitment strategy of force generation and fatigue resistance. Electromyography has earlier been used in several studies to quantify the spatial inhomogeneity of the muscle activation. We applied ultrasound M-mode strain to study the activation pattern through the tissue deformation. Correlation values of the strain at different force levels were used to quantify the spatial changes in the activation. The assessment was done including the biceps brachii muscle of 8 healthy subjects performing isometric elbow flexion contractions ranging from 0% to 80% of maximum voluntary contraction. The obtained results were repeatable and demonstrated consistent changes of the correlation values during force regulation, in agreement with previously presented EMG-results. Both intra-subject and inter-subject activation patterns of strain were considered along and transverse the fiber direction. The results suggest that ultrasound M-mode strain can be used as a complementary method to study intramuscular activation patterns with high spatial resolution.

    (C) 2013 Elsevier Ltd. All rights reserved.

  • 15. Lindberg, Frida
    et al.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Granåsen, Gabriel
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Brodin, Lars-Åke
    Grönlund, Christer
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Pennation angle dependency in skeletal muscle tissue doppler strain in dynamic contractions2011In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 37, no 7, p. 1151-1160Article in journal (Refereed)
    Abstract [en]

    Tissue velocity imaging (TVI) is a Doppler based ultrasound technique that can be used to study regional deformation in skeletal muscle tissue. The aim of this study was to develop a biomechanical model to describe the TVI strain's dependency on the pennation angle. We demonstrate its impact as the subsequent strain measurement error using dynamic elbow contractions from the medial and the lateral part of biceps brachii at two different loadings; 5% and 25% of maximum voluntary contraction (MVC). The estimated pennation angles were on average about 4° in extended position and increased to a maximal of 13° in flexed elbow position. The corresponding relative angular error spread from around 7% up to around 40%. To accurately apply TVI on skeletal muscles, the error due to angle changes should be compensated for. As a suggestion, this could be done according to the presented model.

  • 16. Loras, H.
    et al.
    Stensdotter, A. K.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sigmundsson, H.
    Individual differences in timing of discrete and continuous movements: a dimensional approach2014In: Psychological Research, ISSN 0340-0727, E-ISSN 1430-2772, Vol. 78, no 2, p. 289-299Article in journal (Refereed)
    Abstract [en]

    This study investigated aspects of individual differences in timing of continuous and discontinuous movements to different pacing signals (auditory or visual), pacing intervals (500, 650, 800, 950 ms), and across effectors (dominant versus non-dominant hand). Correlation and principal component analysis demonstrated that a single statistical dimension accounted for up to 60 % of the explained variance in discontinuous tasks and 25 % of the variance in continuous tasks, when applied to performance obtained from tasks conducted with different effectors and at different pacing rates. Correlation analysis of factor scores representing effector and rate independent task performances showed that timing of discrete or continuous movements can be associated with modality independent mechanisms. Timing variability from discrete and continuous trials was not significantly correlated. This study goes beyond previous correlational work on individual differences in discrete and continuous movements, demonstrating that individual differences in discrete (event-based) or continuous (emergent) motor timing tasks can be modeled as distinctive statistical components with dissimilar capability to capture effector, rate, and modality independent variance.

  • 17. Lorås, H
    et al.
    Sigmundsson, H
    Talcott, JB
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Stensdotter, AK
    Timing continuous or discontinuous movements across effectors specified by different pacing modalities and intervals2012In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 220, no 3-4, p. 335-347Article in journal (Refereed)
    Abstract [en]

    Sensorimotor synchronization is hypothesized to arise through two different processes, associated with continuous or discontinuous rhythmic movements. This study investigated synchronization of continuous and discontinuous movements to different pacing signals (auditory or visual), pacing interval (500, 650, 800, 950 ms) and across effectors (non-dominant vs. non-dominant hand). The results showed that mean and variability of asynchronization errors were consistently smaller for discontinuous movements compared to continuous movements. Furthermore, both movement types were timed more accurately with auditory pacing compared to visual pacing and were more accurate with the dominant hand. Shortening the pacing interval also improved sensorimotor synchronization accuracy in both continuous and discontinuous movements. These results show the dependency of temporal control of movements on the nature of the motor task, the type and rate of extrinsic sensory information as well as the efficiency of the motor actuators for sensory integration.

  • 18.
    Lorås, H.
    et al.
    Trondheim, Norway.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Vasseljen, O.
    Trondheim, Norway.
    Stensdotter, A. K.
    Trondheim, Norway.
    Frame-difference analysis of video-recorded laser-beam projections2015In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 20, no 6, p. 879-883Article in journal (Refereed)
    Abstract [en]

    Laser beams have been applied in many human motion research contexts to project movements in specific motor tasks. Currently, there are no objective analysis methods for laser projection recordings. The principal aim of this study was to investigate the feasibility of quantifying motion by applying frame differencing and image analysis methods to video streams of laser beam projections. The laser projection was controlled by a mechanical device that produced pseudo random rotations. The 2D motion recorded by the video was compared with recordings obtained with an electromagnetic system where a sensor was fixed to the same device as the laser. High correlations in the time and frequency domains were found between the methods. We conclude that the proposed method can accurately quantify complex motion patterns from laser beam projections. (C) 2015 Elsevier Ltd. All rights reserved.

  • 19. Lorås, Håvard
    et al.
    Stensdotter, Ann-Katrin
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sigmundsson, Hermundur
    Individual differences in motor timing and its relation to cognitive and fine motor skills2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 7, p. e69353-Article in journal (Refereed)
  • 20.
    Peter, Christian
    et al.
    Graz University ofTechnology, Inffeldgasse 16c, 8010 Graz, Austria.
    Kreiner, Andreas
    Modernfamilies.net GmbH, Linz, Austria.
    Schröter, Martin
    Graz University ofTechnology, Inffeldgasse 16c, 8010 Graz, Austria.
    Kim, Hyosun
    Graz University ofTechnology, Inffeldgasse 16c, 8010 Graz, Austria.
    Beiber, Gerald
    Fraunhofer IGD, Rostock, Germany.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Hoshi, Kei
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Waterworth, Eva
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Waterworth, John
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Ballesteros, Soladad
    Facultad de Psicologia, UNED, Madrid, Spain.
    AGNES: connecting people in a multimodal way2013In: Journal on Multimodal User Interfaces, ISSN 1783-7677, E-ISSN 1783-8738, Vol. 7, no 3, p. 229-245Article in journal (Refereed)
    Abstract [en]

    Western societies are confronted with a number of challenges caused by the increasing number of older citizens. One important aspect is the need and wish of older people to live as long as possible in their own home and maintain an independent life. As people grew older, their social networks disperse, with friends and families moving to other parts of town, other cities or even countries. Additionally, people become less mobile with age, leading to less active participation in societal life. Combined, this normal, age-related development leads to increased loneliness and social isolation of older people, with negative effects on mental and physical health of those people. In the AGNES project, a home-based system has been developed that allows connecting elderly with their families, friends and other significant people over the Internet. As most older people have limited experience with computers and often special requirements on technology, one focus of AGNES was to develop with the users novel technological means for interacting with their social network. The resulting system uses ambient displays, tangible interfaces and wearable devices providing ubiquitous options for interaction with the network, and secondary sensors for additionally generating carefully chosen information on the person to be relayed to significant persons. Evaluations show that the chosen modalities for interaction are well adopted by the users. Further it was found that use of the AGNES system had positive effects on the mental state of the users, compared to the control group without the technology.

  • 21. Rasouli, Omid
    et al.
    Fors, Egil A.
    Borchgrevink, Petter Chr
    Öhberg, Fredrik
    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).
    Stensdotter, Ann-Katrin
    Gross and fine motor function in fibromyalgia and chronic fatigue syndrome2017In: Journal of Pain Research, ISSN 1178-7090, E-ISSN 1178-7090, Vol. 10, p. 303-309Article in journal (Refereed)
    Abstract [en]

    Purpose: This paper aimed to investigate motor proficiency in fine and gross motor function, with a focus on reaction time (RT) and movement skill, in patients with fibromyalgia (FM) and chronic fatigue syndrome (CFS) compared to healthy controls (HC). Methods: A total of 60 individuals (20 CFS, 20 FM, and 20 HC), age 19-49 years, participated in this study. Gross motor function in the lower extremity was assessed using a RT task during gait initiation in response to an auditory trigger. Fine motor function in the upper extremity was measured during a precision task (the Purdue Pegboard test) where the number of pins inserted within 30 s was counted. Results: No significant differences were found between FM and CFS in any parameters. FM and CFS groups had significantly longer RT than HC in the gait initiation (p=0.001, and p=0.004 respectively). In the Purdue Pegboard test, 20% in the FM group, 15% in the CFS groups, and 0% of HC group, scored below the threshold of the accepted performance. However, there were no significant differences between FM, CFS, and HC in this task (p=0.12). Conclusion: Compared to controls, both CFS and FM groups displayed significantly longer RT in the gait initiation task. Generally, FM patients showed the worst results in both tests, although no group differences were found in fine motor control, according to the Purdue Pegboard test.

  • 22.
    Rehn, Börje
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Stenlund, Tobias
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Lindroos, Ola
    Lundström, Ronnie
    Analysis of seated postures using orientation sensors2012Conference paper (Refereed)
  • 23.
    Sehlin, Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology. Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Brändström, Helge
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Winsö, Ola
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Haney, Michael
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Wadell, Karin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Simulated flying altitude and performance of continuous positive airway pressure devices2014In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 85, no 11, p. 1092-1099Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: Continuous positive airway pressure (CPAP) is used in air ambulances to treat patients with impaired oxygenation. Differences in mechanical principles between CPAP devices may affect their performance at different ambient air pressures as will occur in an air ambulance during flight. METHODS: Two different CPAP systems, a threshold resistor device and a flow resistor device, at settings 5 and 10 cm H2O were examined. Static pressure, static airflow and pressure during simulated breathing were measured at ground level and at three different altitudes (2400 m (8 kft), 3000 m (10 kft) and 10700 m (35 kft)). RESULTS: When altitude increased, the performance of the two CPAP systems differed during both static and simulated breathing pressure measurements. With the threshold resistor CPAP, measured pressure levels were close to the preset CPAP level. Static pressure decreased 0.71 ± 0.35 cm H2O, at CPAP 10 cm H2O, comparing ground level and 35 kft. With the flow resistor CPAP, as the altitude increased CPAP produced pressure levels increased. At 35 kft, the increase was 5.13 ± 0.33 cm H2O at CPAP 10 cm H2O. DISCUSSION: The velocity of airflow through the flow resistor CPAP device is strongly influenced by reduced ambient air pressure leading to a higher delivered CPAP effect than the preset CPAP level. Threshold resistor CPAP devices seem to have robust performance regardless of altitude. Thus, the threshold resistor CPAP device is probably more appropriate for CPAP treatment in an air ambulance cabin, where ambient pressure will vary during patient transport.

  • 24.
    Sehlin, Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Sandkvist Törnell, Siv
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Johansson, Göran
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Winsö, Ola
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Pneumatic performance of the boussignac CPAP system in healthy humans2011In: Respiratory care, ISSN 0020-1324, E-ISSN 1943-3654, Vol. 56, no 6, p. 818-826Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The Boussignac CPAP has been found to effectively treat acute pulmonary oedema. However, data on airway pressure in association with the Boussignac CPAP are sparse. We therefore designed this study to evaluate the stability of the Boussignac CPAP in terms of maintaining adequate inspiratory and expiratory pressure levels. We also wanted to evaluate the perceived exertion when breathing with the Boussignac CPAP.

    METHODS: Continuous recordings of airway pressure and airflow were made in 18 healthy volunteers during breathing with the Boussignac CPAP at 5, 7.5 and 10 cm H₂O for three sessions of 10 minutes at each CPAP level. Participants were blinded for the sequential order of the investigated CPAP levels. They terminated each session, at the respective CPAP level, by taking 10 forced breaths.

    RESULTS: During 10 minutes normal breathing periods, when participants breathed at 20 % of their VC with a peak expiratory airflow of 14 % of FEV₁, the maximal pressure difference was 4.0 cm H₂O between inspiration and expiration at CPAP 10 cm H₂O. Changes in airway pressure were never large enough to reduce airway pressure below zero. When taking forced breaths, expiratory volume was 38-42 % of VC and peak expiratory airflow was 49-56 % of FEV ₁. As airflow increased, both the drop in inspiratory airway pressure and the increase in expiratory airway pressure were enhanced.

    CONCLUSIONS: Pressure changes during breathing with CPAP are considered to be associated with increased work of breathing. The pneumatic performance of the Boussignac CPAP is adequate during normal breathing with low airflow. However, during forced breathing resulting in increased airflow, the Boussignac CPAP is unable to maintain stable airway pressure levels, possibly resulting in increased work of breathing and respiratory fatigue. Thus, the Boussignac CPAP system might be less suitable for patients breathing at a higher frequency.

  • 25.
    Sehlin, Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology. Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Winsö, Ola
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Wadell, Karin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Immediate effects of positive expiratory pressure and continuous positive airway pressure breathing on changes in inspiratory capacity as an indirect measure of induced changes in functional residual capacity in healthy individualsManuscript (preprint) (Other academic)
    Abstract [en]

    Introduction: Positive expiratory pressure (PEP) and continuous positive airway pressure (CPAP) are used to enhance breathing parameters such as functional residual capacity (FRC) in patients. Studies comparing effects of PEP and CPAP on FRC are sparse. One reason for this may be that sophisticated equipment, not suitable in the clinical setting, is required. Total lung capacity consists of inspiratory capacity (IC) and FRC and a change in IC should therefore result in a corresponding change in FRC. We aimed to investigate if PEP and CPAP induced changes in IC could be used as an indirect measure of changes in FRC and also to evaluate immediate effects of PEP and CPAP devices, with different kinds of resistors, on IC. 

    Methods: 20 healthy volunteers breathed with two PEP devices, a PEP-mask (flow resistor) and a PEP-bottle (threshold resistor) and two CPAP devices, a flow resistor device and a threshold resistor device, in a randomized order. The measurement sequence consisted of 30 breaths with an IC measurement performed before and immediately after the 30th breath, while the participants were still connected to the respective breathing device. Perceived exertion of the respective 30 breaths was measured with Borg CR10 scale.

    Results: Three of the four breathing devices, the PEP-mask and the two CPAP devices, significantly decreased IC (p < 0.001). Median perceived exertion was quite low for all four breathing devices but the difference in perceived exertion within the different breathing devices was large.

    Conclusion: When measured in direct continuation of PEP and CPAP breathing, changes in IC could be used as an indirect measure of changes in FRC. All investigated breathing devices except the PEP-bottle decreased IC, i.e. increased FRC.

  • 26.
    Sehlin, Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology. Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Winsö, Ola
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Wadell, Karin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Inspiratory Capacity as an Indirect Measure of Immediate Effects of Positive Expiratory Pressure and CPAP Breathing on Functional Residual Capacity in Healthy Subjects2015In: Respiratory care, ISSN 0020-1324, E-ISSN 1943-3654, Vol. 60, no 10, p. 1486-1494Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Positive expiratory pressure (PEP) and CPAP are used to enhance breathing parameters such as functional residual capacity (FRC) in patients. Studies comparing effects of PEP and CPAP on FRC are few and variable. One reason for this may be that sophisticated equipment, not suitable in the clinical setting, is required. Because total lung capacity (TLC) consists of inspiratory capacity (IC) and FRC, a change in IC should result in a corresponding change in FRC given constant TLC. We aimed to evaluate the effects of different PEP and CPAP devices on IC as an indirect measure of induced changes in FRC from these devices in healthy subjects. METHODS: Twenty healthy subjects breathed with 2 PEP devices, a PEP mask (flow resistor) and a PEP bottle (threshold resistor), and 2 CPAP devices, a flow resistor and a threshold resistor, in a randomized order. The measurement sequence consisted of 30 breaths with an IC measurement performed before and immediately after the 30th breath while the subjects were still connected to the breathing device. Perceived exertion of the 30 breaths was measured with the Borg category ratio 10 scale. RESULTS: Three of the 4 breathing devices, the PEP mask and the 2 CPAP devices, significantly decreased IC (P <.001). Median perceived exertion was quite low for all 4 breathing devices, but the difference in perceived exertion among the different breathing devices was large. CONCLUSIONS: Provided that TLC is constant, we found that measurements of changes in IC could be used as an indirect measure of changes in FRC in healthy subjects. All investigated breathing devices except the PEP bottle decreased IC, as an indirect measure of increased FRC.

  • 27.
    Sehlin, Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Johansson, Göran
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Winsö, Ola
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Physiological responses to positive expiratory pressure breathing: a comparison of the PEP bottle and the PEP mask2007In: Respiratory care, ISSN 0020-1324, E-ISSN 1943-3654, Vol. 52, no 8, p. 1000-1005Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: In the intensive care unit we have observed that patients have different adherence to 2 commonly used positive-expiratory-pressure (PEP) therapy devices: the PEP bottle and the PEP mask. The reason for this difference is not clear. METHODS: In a randomized prospective study, we made continuous recordings of airway pressure and airflow, with 20 healthy volunteers, with the PEP bottle and the PEP mask. The measurement sequence consisted of 3 sessions of 10 breaths with the PEP bottle and the PEP mask, in a randomized crossover design. A rest period of 15 min separated the PEP bottle and PEP mask measurements. RESULTS: With the PEP bottle the expiratory phase began with a zero-flow period of 0.39 s, during which airway pressure rose 11.9 cm H2O. With the PEP bottle the mean expiratory pressure was 11.7 cm H2O, and end-expiratory pressure was 9.5 cm H2O. With the PEP mask the initial expiratory zero-flow period was almost nonexistent (0.04 s) and without any change in airway pressure. With the PEP mask the shape of the expiratory pressure curve was different; mean expiratory pressure was 8.6 cm H2O, and end-expiratory pressure was zero. With the PEP bottle the inspiration also began with a zero-flow period of 0.43 s, during which airway pressure decreased 9.6 cm H2O from the end-expiratory airway pressure. With the PEP mask the initial inspiratory zero-flow period was only 0.01 s and there was no concomitant change in airway pressure. CONCLUSIONS: The PEP bottle and the PEP mask showed major differences in the relationship between airflow and airway pressure. These findings might explain the observed differences in patient adherence to these therapies.

  • 28.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lindroos, Ola
    Institutionen för skogens biomaterial och teknologi (SBT), Sveriges lantbruksuniversitet, Umeå.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Neely, Gregory
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Adaptation of postural reactions in seated positions and influence of head posture when exposed to a single sideway perturbation: relevance for driving on irregular terrain2016In: Journal of Novel Physiotherapy and Physical Rehabilitation, ISSN 2455-5487, Vol. 3, no 1, p. 022-029Article in journal (Refereed)
    Abstract [en]

     Background and objectives: Mechanical perturbations in seated positions caused by driving on irregular terrain destabilize the driver which, combined with the drivers’ posture, may cause musculoskeletal disorders. The aim of this study was to investigate adaptation and the effect of different head postures on seated postural reactions caused by perturbations. 

    Materials and Methods: Twenty healthy male participants, aged 18-43 years, were tested on a movable platform delivering 15 sideways perturbations (peak acceleration 13.3 m/s2) while the participants held their head in a neutral or a laterally flexed posture. Surface electromyography (EMG) signals were recorded bilaterally in upper neck, trapezius, erector spinae and external oblique, while kinematics were recorded with inertial sensors for the head, trunk and pelvis. EMG amplitudes, muscle onset latencies and angular displacements in the frontal plane were analyzed. 

    Results: In the neutral position, the EMG amplitudes and neck angular displacements significantly decreased by 0.2% and more than 1.6° respectively after repeated perturbations. Muscle onset latencies remained unchanged. During lateral flexion of the head, the EMG amplitudes decreased by 0.5% but the muscular onset latencies increased by more than 9 ms. 

    Conclusion: The developed neuromuscular strategy seem to prefer a reduced EMG amplitude. The modest size of the postural reactions during the conditions presented here do not by themselves explain the musculoskeletal disorders found in drivers.

  • 29.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lindroos, Ola
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Neely, Gregory
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Double-sided Mechanical Shocks Provoke Larger Seated Postural Reactions Compared to Single-Sided Mechanical Shocks2018In: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 43, no 8, p. E482-E487Article in journal (Refereed)
    Abstract [en]

    STUDY DESIGN: Human volunteers were exposed experimentally to single-sided mechanical shocks (SSMS) and double-sided mechanical shocks (DSMS) while seated.

    OBJECTIVE: To describe and contrast seated postural reactions due to SSMS or DSMS in healthy male adults.

    SUMMARY OF BACKGROUND DATA: Mechanical shocks to the body, caused when driving on irregular terrain, are suggested to be hazardous to the spine and may be associated with the reported musculoskeletal pain of the back and neck among professional drivers. However, very little is known about the characteristics of seated postural reactions and the biomechanical effects caused by mechanical shocks.

    METHODS: Twenty healthy male subjects (18-43 years old) were exposed while seated to 5 SSMS and 15 DSMS in lateral directions. The second acceleration in the DSMS was in the opposite direction to the first acceleration and was either fast, medium or slow depending on the speed of direction change. Surface electromyography (EMG) was recorded in muscles of the upper neck, trapezius, erector spinae and external oblique while kinematics were recorded with inertial sensors placed at the neck, trunk and pelvis. Muscle activity was normalized to maximum voluntary contractions (MVC).

    RESULTS: The EMG amplitudes were significantly higher (0.6-1%; p < 0.001) for the fast DSMS compared to all other shocks. Range of motion (ROM) of the neck and trunk was greater during the DSMS compared to the SSMS. Evoked muscle activity was less than 2% MVC in the trapezius, less than 10% MVC in the erector spinae and upper neck while the activity exceeded 10% MVC in the external oblique muscles.

    CONCLUSION: Fast DSMS in lateral directions appear more demanding compared to SSMS, demonstrating augmented seated postural reactions. However, the present mechanical shocks employed did not seem to induce postural reactions with regard to ROM or muscle activity of a magnitude likely to cause musculoskeletal overload.

    LEVEL OF EVIDENCE: 4.

  • 30.
    Stenlund, Tobias
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lundström, Ronnie
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lindroos, Ola
    Dept. of Forest Biomaterials & Technology, Swedish University of Agricultural Sciences, Sweden.
    Häger, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Rehn, Börje
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Inter- and intra-tester reliability when measuring seated spinal postures with inertial sensors2014In: International Journal of Industrial Ergonomics, ISSN 0169-8141, E-ISSN 1872-8219, Vol. 44, no 5, p. 732-738Article in journal (Refereed)
    Abstract [en]

    Prolonged awkward sitting postures may be associated with neck or back pain, but it is often unclear which specific postures cause most problems and which mechanisms that may underlie the pain. In order to increase the knowledge in this field, it seems crucial first of all to be able to analyse, in depth, different seated spinal postures. A problem is however the lack of reliable and direct measurement methods of the posture, especially for sitting. Recently developed systems with inertial sensor attached along the spine have potential for this purpose. The aim of the present study was therefore to test the reliability of using such a system to assess various seated postures. Inter- and intra-tester as well as intra-subject relative reliability was estimated with intra-class correlation coefficient (ICC). Absolute reliability was estimated with standard error of measurement (SEM) and smallest detectable change (SDC). Ten + ten healthy subjects and four testers participated. Three standardised unsupported seated postures (lumbar lordosis, lumbar kyphosis and neutral posture) and two standing postures (neutral and lumbar kyphosis) were evaluated using five sensors attached to the head, the thorax (high and low), the lumbar spine and the pelvis. The ICC for intra-tester reliability ranged from 0.37 to 0.90, SEM 2.5-12.0 degrees, and SDC 7.1-333 degrees where the largest measurement error was from the head. Intra-tester reliability was higher than inter-tester reliability but not as good as intra-subject reliability. The intra-tester absolute reliability was nevertheless not considered sufficient to distinguish smaller differences. The low reliability may depend on inertial sensor size and attachment but also on the tester's accuracy. This study shows that assessing unsupported seated spinal postures with inertial sensors could be performed with higher reliability if done by the same, rather than different, testers. Relevance to industry: Prolonged awkward seated postures at work may be associated with back and neck pain and should therefore be analysed. Inertial sensor units is a promising tool to measure spinal posture. Smaller sensors attached by one skilled tester directly onto the body will most likely improve assessment in the future. (C) 2014 Elsevier B.V. All rights reserved.

  • 31. Stensdotter, A.
    et al.
    Pedersen, N.
    Wanvik, A.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Flovig, J. C.
    Fors, E. A.
    Upper body 3-dimensional kinematics during gait in psychotic patients: a pilot-study2012In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 221, no 4, p. 393-401Article in journal (Refereed)
    Abstract [en]

    Gait is recognized as a key item related to mental function. Anomalous gait in psychotic individuals has been described for the lower extremities, whereas irregularities for upper body dynamics are not described, explained or verified with unbiased methods. Reduced walking velocity and increased somatic tension defined in this patient category may influence upper body dynamics during gait. The aim of this pilot-study was to describe upper body kinematics and investigate the biomechanical association with walking velocity and muscle tension. Twelve inpatients in a psychiatric ward with first-episode psychosis and 18 healthy control subjects walked at different self-chosen velocities. Movement and walking velocity were registered, and 3D kinematics was analysed for thorax and shoulder joint. Time-synchronized EMG from the trapezius muscle, chosen as indicator for general somatic tension, was analysed for maximal amplitude and variability. Results showed that patients walked with reduced arm swing at the shoulder joint and increased lateral thorax movements. Thorax rotations about the vertical axis, walking velocity and EMG measures were similar in patients and healthy subjects. The present study could not provide a biomechanical explanation for kinematic findings based on walking velocity or somatic tension.

  • 32.
    Stensdotter, Ann-Katrin
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Hodges, Paul
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Häger-Ross, Charlotte
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Quadriceps EMG in Open and Closed Kinetic Chain Tasks in Women With Patellofemoral Pain.2007In: Journal of motor behavior, ISSN 0022-2895, E-ISSN 1940-1027, Vol. 39, no 3, p. 194-202Article in journal (Refereed)
    Abstract [en]

    The authors investigated whether the discrepancy noted in the literature regarding delayed and decreased activity in vastus medialis obliquus (VMO) in people with patellofemoral pain (PFP) depends on the nature of the open kinetic chain (OKC) and the closed kinetic chain (CKC) in the experimental task. They hypothesized that activity in VMO would be more delayed and decreased in CKC tasks than in OKC tasks. Women with PFP (n = 17) and healthy controls (n = 17) performed isometric quadriceps contractions in CKC and OKC tasks. The authors manipulated only the application of resistance. Electromyographs (EMGs) showed that participants with PFP reacted later and activated the quadriceps more in the CKC task but had intramuscular quadriceps coordination similar to that of controls. The nature of the OKC task or the CKC task does not seem to explain contradictory findings regarding VMO activation.

  • 33.
    Wadell, Karin
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Bergmann, Eva
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Holmner, Åsa
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Longitudinal, home-based study of lung function, saturation and disease-related symptoms in COPD2018In: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 52Article in journal (Other academic)
    Abstract [en]

    Background: Many telehealth (TH) systems have been designed to identify signs of COPD exacerbations, but few previous studies have reported the nature of recorded lung function data and what variations to expect in stable versus unstable patients.

    Aims: To evaluate the nature of individual diurnal, day-to-day and long-term variation in important prognostic markers of COPD exacerbations in a heterogeneous patient group by employing a newly developed TH system.

    Methods: Eight women and five men with COPD performed measurements (FEV1, IC, SpO2 and CAT) three times per week during 4-6 months using the TH system. Feasibility was based on the repeatability and quality of the FEV1 and IC measurements, as defined by ERS/ATS guidelines. Short-term and long-term individual variations were assessed using the relative density and mean (SD) respectively.

    Results: Close to 1100 FEV1 and IC measurements respectively were performed during a total of 240 patient weeks. The 2SD ranges for intra-individual variation were ± 210 mL and ± 350 mL for FEV1 and IC respectively. The values both increased and decreased without corresponding influence on symptoms (CAT) or SpO2 and no exacerbation was reported. However, it was unusual with a decrease of more than 50 mL per measurement in FEV1 between three consecutive measurement days.

    Conclusions: This study reveals important and, to our knowledge, previously not reported information about short and long-term variability in lung function measurements in stable patients with COPD, of significance when defining criteria for detecting exacerbations with TH systems.

  • 34.
    Wahlström, Viktoria
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Bergman, Frida
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Eskilsson, Therese
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Slunga-Järvholm, Lisbeth
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Effects of a multicomponent physical activity promoting program on sedentary behavior, physical activity and body measures: a longitudinal study in different office types2019In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 45, no 5, p. 493-504Article in journal (Refereed)
    Abstract [en]

    Objectives: The aim of this study was to investigate effects of a multicomponent program promoting physical activity on sedentary behavior, physical activity, and body measures, when relocating from cell offices to either a flex or cell office.

    Methods: The Active Office Design (AOD) study is a longitudinal non-randomized controlled study performed in a municipality in northern Sweden. A subsample of 86 participants were randomly recruited from the AOD study to objectively measure sedentary behavior and physical activity, using ActivPAL and ActiGraph, before and after relocation to the two different office types. The multicomponent program promoting physical activity was performed in both offices. Data were analyzed using linear mixed models.

    Results: Eighteen months after relocation, the total number of steps per work day increased by 21% in the flex office and 3% in the cell office group, compared to baseline. Moderate and vigorous physical activity (MVPA) during work hours increased by 42% in the flex office group and 19% in the cell office group. No changes were seen regarding sitting time at work. Small additive effects for walking and MVPA were seen for both groups during non-work time. Weight increased in the flex office group.

    Conclusions: This long-term study shows that a multicomponent workplace intervention can lead to increased walking time, steps, and MVPA in a flex compared to a cell office. Small additive increases of physical activity were seen during non-work time in both groups. More long-term controlled studies are needed to confirm these results.

  • 35.
    Wahlström, Viktoria
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Bergman, Frida
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Stenlund, Therese
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Slunga-Järvholm, Lisbeth
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    A longitudinal study of physical activity in different office types2018In: Journal of Physical Activity and Health, ISSN 1543-3080, E-ISSN 1543-5474, Vol. 15, no 10, p. S62-S62Article in journal (Other academic)
  • 36.
    Wahlström, Viktoria
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Olsson, David
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Slunga-Järvholm, Lisbeth
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Sustainable Health.
    Underlying factors explaining sedentary behavior and physical activity among office workers - an exploratory analysisManuscript (preprint) (Other academic)
  • 37.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Biomechanical methods and error analysis related to chronic musculoskeletal pain2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background Spinal pain is one of humanity’s most frequent complaints with high costs for the individual and society, and is commonly related to spinal disorders. There are many origins behind these disorders e.g., trauma, disc hernia or of other organic origins. However, for many of the disorders, the origin is not known. Thus, more knowledge is needed about how pain affects the neck and neural function in pain affected regions. The purpose of this dissertation was to improve the medical examination of patients suffering from chronic whiplash-associated disorders or other pain related neck-disorders.

    Methods A new assessment tool for objective movement analysis was developed. In addition, basic aspects of proprioceptive information transmission, which can be of relevance for muscular tension and pain, are investigated by studying the coding of populations of different types of sensory afferents by using a new spike sorting method. Both experiments in animal models and humans were studied to accomplish the goals of this dissertation. Four cats where were studied in acute animal experiments. Mixed ensembles of afferents were recorded from L7-S1 dorsal root filaments when mechanical stimulating the innervated muscle. A real-time spike sorting method was developed to sort units in a multi-unit recording. The quantification of population coding was performed using a method based on principal component analysis. In the human studies, 3D neck movement data were collected from 59 subjects with whiplash-associated disorders (WAD) and 56 control subjects. Neck movement patterns were identified by processing movement data into parameters describing the rotation of the head for each subject. Classification of neck movement patterns was performed using a neural network using processed collected data as input. Finally, the effect of marker position error on the estimated rotation of the head was evaluated by computer simulations.

    Results Animal experiments showed that mixed ensembles of different types of afferents discriminated better between different muscle stimuli than ensembles of single types of these afferents. All kinds of ensembles showed an increase in discriminative ability with increased ensemble size. It is hypothesized that the main reason for the greater discriminative ability might be the variation in sensitivity tuning among the individual afferents of the mixed ensemble will be larger than that for ensembles of only one type of afferent. In the human studies, the neural networks had a predictivity of 0.89, a sensitivity of 0.90 and a specificity of 0.88 when discriminating between control and WAD subjects. Also, a systematic error along the radial axis of the rigid body added to a single marker had no affect on the estimated rotation of the head.

    Conclusion The developed spike sorting method, using neural networks, was suitable for sorting a multiunit recording into single units when performing neurophysiological experiments. Also, it was shown that neck movement analysis combined with a neural network could build the basis of a decision support system for classifying suspected WAD or other pain related neck-disorders.

  • 38.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    The effect of anisotropic systematic errors in estimating helical angles2008In: Computer Methods in Biomechanics and Biomedical Engineering, ISSN 1025-5842, E-ISSN 1476-8259, Vol. 11, no 2, p. 205-213Article in journal (Refereed)
    Abstract [en]

    A common question in movement studies is how the results should be interpreted with respect to systematic and random errors. In this study, simulations are made in order to see how a rigid body's orientation in space (i.e. helical angle between two orientations) is affected by (1) a systematic error added to a single marker (2) a combination of this systematic error and Gaussian white noise. The orientation was estimated after adding a systematic error to one marker within the rigid body. This procedure was repeated with Gaussian noise added to each marker.

    In conclusion, results show that the systematic error's effect on estimated orientation depends on number of markers in the rigid body and also on which direction the systematic error is added. The systematic error has no effect if the error is added along the radial axis (i.e. the line connecting centre of mass and the affected marker).

  • 39.
    Öhberg, Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Bäcklund, Tomas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sundström, Nina
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Portable Sensors Add Reliable Kinematic Measures to the Assessment of Upper Extremity Function2019In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, no 5, article id 1241Article in journal (Refereed)
    Abstract [en]

    Ordinal scales with low resolution are used to assess arm function in clinic. These scales may be improved by adding objective kinematic measures. The aim was to analyze within-subject, inter-rater and overall reliability (i.e., including within-subject and inter-rater reliability) and check the system's validity of kinematic measures from inertial sensors for two such protocols on one person. Twenty healthy volunteers repeatedly performed two tasks, finger-to-nose and drinking, during two test sessions with two different raters. Five inertial sensors, on the forearms, upper arms and xiphoid process were used. Comparisons against an optical camera system evaluated the measurement validity. Cycle time, range of motion (ROM) in shoulder and elbow were calculated. Bland-Altman plots and linear mixed models including the generalizability (G) coefficient evaluated the reliability of the measures. Within-subject reliability was good to excellent in both tests (G = 0.80-0.97) and may serve as a baseline when assessing upper extremities in future patient groups. Overall reliability was acceptable to excellent (G = 0.77-0.94) for all parameters except elbow axial rotation in finger-to-nose task and both elbow axial rotation and flexion/extension in drinking task, mainly due to poor inter-rater reliability in these parameters. The low to good reliability for elbow ROM probably relates to high within-subject variability. The sensors provided good to excellent measures of cycle time and shoulder ROM in non-disabled individuals and thus have the potential to improve today's assessment of arm function.

  • 40.
    Öhberg, Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sterner, Ylva
    Karlsson, J Stefan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Gerdle, Björn
    Chronic whiplash associated disorders and neck movement measurements: an instantaneous helical axis approach.2003In: IEEE transactions on information technology in biomedicine, ISSN 1089-7771, E-ISSN 1558-0032, Vol. 7, no 4, p. 274-282Article in journal (Refereed)
    Abstract [en]

    This paper presents an assessment tool for objective neck movement analysis of subjects suffering from chronic whiplash-associated disorders (WAD). Three-dimensional (3-D) motion data is collected by a commercially available motion analysis system. Head rotation, defined in this paper as the rotation angle around the instantaneous helical axis (IHA), is used for extracting a number of variables (e.g., angular velocity and range, symmetry of motion). Statistically significant differences were found between controls and subjects with chronic WAD in a number of variables.

  • 41.
    Öhberg, Fredrik
    et al.
    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).
    Lundström, Ronnie
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Grip, Helena
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Comparative analysis of different adaptive filters for tracking lower segments of a human body using inertial motion sensors2013In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 24, no 8, p. 085703-Article in journal (Refereed)
    Abstract [en]

    For all segments and tests, a modified Kalman filter and a quasi-static sensor fusion algorithm were equally accurate (precision and accuracy similar to 2-3 degrees) compared to normalized least mean squares filtering, recursive least-squares filtering and standard Kalman filtering. The aims were to: (1) compare adaptive filtering techniques used for sensor fusion and (2) evaluate the precision and accuracy for a chosen adaptive filter. Motion sensors (based on inertial measurement units) are limited by accumulative integration errors arising from sensor bias. This drift can partly be handled with adaptive filtering techniques. To advance the measurement technique in this area, a new modified Kalman filter is developed. Differences in accuracy were observed during different tests especially drift in the internal/external rotation angle. This drift can be minimized if the sensors include magnetometers.

  • 42.
    Öhberg, Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Wadell, Karin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Claesson, Kenji
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Edström, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Holmner, Åsa
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Home-based system for recording pulmonary function and disease-related symptoms in patients with chronic obstructive pulmonary disease, COPD: a pilot study2016In: SM Journal of Pulmonary Medicine, ISSN 2574-240X, Vol. 2, no 1, article id 1011Article in journal (Refereed)
    Abstract [en]

    Introduction: Many patients with Chronic Obstructive Pulmonary Disease (COPD) suffer from acute exacerbations characterized by an increase in symptoms beyond normal day-to-day variation. The prognosis of patients with frequent exacerbations is poor and effort to curb these worsening episodes has great potential to improve the patient’s quality of life and to reduce associated costs. Telemonitoring has been proposed as a promising strategy in this respect. However, information on what physical signs or symptoms that should be recorded and how recorded data should be interpreted is largely missing in the literature.

    Methods: A new home-based system, based on a tablet computer, which can guide COPD patients to perform spirometry (inspiratory capacity, IC and forced expiratory volume in one and six seconds, FEV1 and FEV6) and record symptoms (COPD assessment test, CAT) was developed. The system was evaluated for 8-12 weeks in four patients with moderate to severe COPD with the aims to; i) assess the feasibility of the system to be used unsupervised by COPD patients and, ii) to evaluate the quality and ability of recorded parameters to reveal early signs of an exacerbation. Pearson bivariate correlation was performed between all outcome measures and descriptive information about inherent subject properties were presented.

    Results: The system was well accepted by all study subjects and the study generated a total of 253 measurements of which 94.5% were considered acceptable for analysis. One of the subjects developed an acute exacerbation towards the end of the study, whereas the other three subjects remained stable. Descriptive analysis of the data suggest that trends in the CAT score may indicate changes in health status and that IC tends to be more responsive to these changes compared to FEV1.

    Conclusion: The system developed in this study is well suited to be used unsupervised by COPD patients. Recorded data, in particular CAT, may be sensitive enough to detect early signs of an acute COPD exacerbation, although more data is needed to fully resolve the nature of such an association.

  • 43.
    Öhberg, Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Zachrisson, Adam
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Holmner-Rocklöv, Åsa
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Three-Dimensional Camera System for Measuring Arm Volume in Women with Lymphedema Following Breast Cancer Treatment2014In: Lymphatic Research and Biology, ISSN 1539-6851, E-ISSN 1557-8585, Vol. 12, no 4, p. 267-274Article in journal (Refereed)
    Abstract [en]

    Background: Lymphedema is a common complication following breast cancer treatment, estimated to affect 20% of breast cancer survivors. The condition is associated with a number of symptoms, such as impaired range of motion and anxiety. A wide range of methods for determining the volume of the lymphedematous arm have been described. Circumference measurement (CM) is commonly used in clinics to appraise arm volume, while water displacement (WD) is often used in studies. The aim of the study was to assess the performance of a new method using 3D-technology in comparison to CM and WD. Methods and Results: The study was performed on 25 subjects with lymphedema secondary to breast cancer treatment. Volumetric data from CM, WD, and the 3D-camera were gathered on all subjects. The measurements were performed by two physiotherapists, each subject being measured by one of the physiotherapist. Estimates of differences between the methods was calculated through analyzing the data collected from the three methods using mixed-design analyses of variance. The results indicated a tendency for the 3D-camera to overestimate the volume in comparison the WD by 45.25 mL, 95% confidence interval (CI) -36.31 - 126.82 (p value 0.270). Conversely, CM showed a tendency to underestimate the volume compared to WD (-24.28 mL, CI -99.78 - 51.22, p value 0.521). Thus, no statistically significant difference was found between the methods. Conclusions: The 3D-camera is a viable method for measuring arm volume, performing on level with the established methods WD and CM.

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