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  • 1.
    Alvehus, Malin
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Boman, Niklas
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Söderlund, Karin
    Svensson, Michael B.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Buren, Jonas
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Metabolic adaptations in skeletal muscle, adipose tissue, and whole-body oxidative capacity in response to resistance training2014Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, nr 7, s. 1463-1471Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of resistance training on mitochondrial biogenesis and oxidative capacity in skeletal muscle are not fully characterized, and even less is known about alterations in adipose tissue. We aimed to investigate adaptations in oxidative metabolism in skeletal muscle and adipose tissue after 8 weeks of heavy resistance training in apparently healthy young men. Expression of genes linked to oxidative metabolism in the skeletal muscle and adipose tissue was assessed before and after the training program. Body composition, peak oxygen uptake (VO2 peak), fat oxidation, activity of mitochondrial enzyme in muscle, and serum adiponectin levels were also determined before and after resistance training. In muscle, the expression of the genes AdipoR1 and COX4 increased after resistance training (9 and 13 %, respectively), whereas the expression levels of the genes PGC-1 alpha, SIRT1, TFAM, CPT1b, and FNDC5 did not change. In adipose tissue, the expression of the genes SIRT1 and CPT1b decreased after training (20 and 23 %, respectively). There was an increase in lean mass (from 59.7 +/- A 6.1 to 61.9 +/- A 6.2 kg), VO2 peak (from 49.7 +/- A 5.5 to 56.3 +/- A 5.0 ml/kg/min), and fat oxidation (from 6.8 +/- A 2.1 to 9.1 +/- A 2.7 mg/kg fat-free mass/min) after training, whereas serum adiponectin levels decreased significantly and enzyme activity of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase did not change. Despite significant increases in VO2 peak, fat oxidation, and lean mass following resistance training, the total effect on gene expression and enzyme activity linked to oxidative metabolism was moderate.

  • 2.
    Björklund, Martin
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Crenshaw, A G
    Djupsjöbacka, M
    Johansson, H
    Letter to the editor: Position sense acuity is diminished following repetitive low-intensity work to fatigue in a simulated occupational setting: a critical comment2003Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 88, nr 4-5, s. 485-486Artikel i tidskrift (Refereegranskat)
  • 3.
    Björklund, Martin
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Crenshaw, Albert G
    Djupsjöbacka, Mats
    Johansson, H
    Position sense acuity is diminished following repetitive low-intensity work to fatigue in a simulated occupational setting.2000Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 81, nr 5, s. 361-367Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Repetitive work to fatigue is soundly associated with work-related musculoskeletal disorders (WMSD), although the underlying mechanisms are poorly understood. In the present study, we tested the hypothesis that fatiguing work leads to proprioceptive deficits, which can be an initiating factor for the occurrence of WMSD. Thus, the position sense of the shoulder was determined for 13 males and 13 females before and after performing repetitive low-intensity arm work to fatigue in a simulated occupational setting. From a starting position of 45° to the sagittal plane, position sense tests consisted of subjects attempting to actively reproduce target positions of horizontal movements to 15° and 30° (shoulder adduction) and to 60° and 75° (shoulder abduction). An analysis of variance revealed that the absolute error was significantly increased following fatigue for the subjects as a group (P < 0.001). Furthermore, females had an overall higher error than males (P < 0.01). No difference in error was detected for the shorter movements versus the longer movements. However, the overall absolute error for adduction was significantly higher than for abduction (P < 0.001). The results of the present study support the hypothesis of diminished proprioceptive acuity following low-intensity work to fatigue. A reduction in position sense acuity could lead to impairment in motor control, which would further impact on position sense. Thus, a vicious cycle may be activated that might result in WMSD. The poorer position sense acuity observed for females may contribute to the explanation of why females demonstrate a higher incidence of WMSD than males.

  • 4.
    Bogdanis, Gregory C.
    et al.
    Faculty of Physical Education & Sport Science, Uniersity of Athens.
    Papaspyrou, Aggeliki
    Faculty of Physical Education & Sport Science, Uniersity of Athens.
    Theos, Apostolos
    Faculty of Physical Education & Sport Science, Uniersity of Athens.
    Maridaki, Maria
    Faculty of Physical Education & Sport Science, Uniersity of Athens.
    Influence of resistive load on power output and fatigue during intermittent sprint cycling exercise in children2007Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 101, nr 3, s. 313-320Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study examined the effects of two resistive loads on fatigue during repeated sprints in children. Twelve 11.8 (0.2) year old boys performed a force-velocity test to determine the load (Fopt) corresponding to the optimal pedal rate. On two separate occasions, ten 6-s sprints interspersed with 24-s recovery intervals were performed on a friction-loaded cycle ergometer, against a load equal to Fopt or 50%Fopt. Although mean power output (MPO) was higher in the Fopt [397 (24) and 356 (19) W, P < 0.01], the decline in MPO over the 10 sprints was similar in Fopt [8.8 (1.9) %] and 50%Fopt [9.0 (2.4) %]. In contrast, peak power (PPO) was not different in sprint 1 between the two conditions [459 (24) and 460 (28) W], but was decreased only in 50%Fopt [11.4 (3.2) %, P < 0.01], while it was maintained in the Fopt despite the higher total work during each sprint. Fatigue within each sprint (percent drop from peak to end power output) was also higher in the 50%Fopt compared with the Fopt [32 (2.5) vs. 10 (1.6) %, P < 0.01]. Peak and mean pedal rate in Fopt condition were close to the optimum (Vopt), while a large part of the sprint time in 50%Fopt was spent far from Vopt. The present study shows that sprinting against Fopt reduces fatigue within and between repeated short sprints in children. It is suggested that fatigue during repeated sprints is modified when pedal rate is not close to Vopt, according to the parabolic power versus pedal rate relationship.

  • 5.
    Carlsson, Magnus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Carlsson, Tomas
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Knutsson, Magnus
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden, Sweden.
    Tonkonogi, Michail
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Oxygen uptake at different intensities and sub-techniques predicts sprint performance in elite male cross-country skiers2014Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, nr 12, s. 2587-2595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PURPOSE: To investigate the relationship between sprint-prologue performance (using the classical technique) and the oxygen uptake at the lactate threshold (V̇O2obla), maximal oxygen uptake (V̇O2max), and mean oxygen uptake during double poling (V̇O2dp).

    METHODS: Eight elite male cross-country skiers [age 24.8 ± 4.8 years, (mean ± SD)] completed two treadmill roller-skiing tests using the diagonal-stride technique and a 60 s double-poling test on a ski-ergometer to determine their V̇O2obla, V̇O2max, and V̇O2dp. Performance data were generated from a 1.25 km sprint prologue. Power-function modelling was used to predict the skiers' race speeds based on the oxygen-uptake variables and body mass.

    RESULTS: There were correlations between the race speed and the absolute expression of the V̇O2obla (r = 0.79, P = 0.021), V̇O2max (r = 0.86, P = 0.0069), and V̇O2dp (r = 0.94, P = 0.00062). The following power-function models were established for race-speed prediction: 1.09 · V̇O2obla(0.21), 1.05 · V̇O2max(0.21), and 1.19 · V̇O2dp(0.20); these models explained 60 % (P = 0.024), 73 % (P = 0.0073), and 87 % (P = 0.00073), respectively, of the variance in the race speed. However, body mass did not contribute to any of the models (P = 0.97, 0.88, and 0.21, respectively).

    CONCLUSIONS: Oxygen uptake at different intensities and sub-techniques is an indicator of elite male sprint-prologue performance. The absolute expression of the investigated oxygen-uptake variables should be used when evaluating elite male sprint-prologue performances; if skiers oxygen uptake differs by 1 %, their performances will likely differ by 0.2 % in favour of the skier with higher oxygen uptake.

  • 6. Crenshaw, Albert G
    et al.
    Elcadi, Guilherme H
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Rehabiliteringsmedicin.
    Hellström, Fredrik
    Mathiassen, Svend Erik
    Reliability of near-infrared spectroscopy for measuring forearm and shoulder oxygenation in healthy males and females2012Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, nr 7, s. 2703-2715Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study determined the day-to-day reliability of NIRS-derived oxygenation responses (a dagger StO(2)%) for isometric contractions and for cuff occlusion. Twenty-four subjects (12 males and 12 females) were tested for 2 days (4-6 days interval). Variables generated were: (1) a dagger StO(2)% for isometric contractions (10, 30, 50 and 70% MVC) for descending trapezius (TD) and extensor carpi radialis (ECR) muscles; (2) slope changes in total haemoglobin (HbTslope) and deoxyhaemoglobin (HHbslope) for the ECR using upper arm venous (VO, 50 mmHg) and arterial occlusion (AO, 250 mmHg); (3) recovery slopes (Rslope) for oxygen saturation (StO(2)) following isometric contractions and AO. For each variable, an intraclass correlation (ICC) was calculated to assess the ability to differentiate between subjects, and limits of agreement (LOA) were computed to assess day-to-day consistency of the measurement. ICCs for Delta StO(2)% were lowest at 10% MVC for both ECR (0.58) and TD (0.55), and highest at 30% MVC for ECR (0.95) and at 70% MVC for TD (0.79). For both muscles, LOA for Delta StO(2)% was lowest at 10% and highest at 50 and 70% MVC. ICC for HbTslope was 0.17. For HHbslope ICC was higher for AO (0.83) than for VO (0.73), and LOA was lower for AO. For the ECR Rslope ICCs ranged from 0.88 to 0.90 for contraction, but was lower for AO (0.33); LOA was lowest at 70% MVC. For trapezius Rslope ICCs ranged from 0.63 to 0.73 and LOA was lowest at 30% MVC. For this study, establishing reliability data for the ECR and TD and including variables commonly reported are expected to have meaning for future NIRS studies of work-related upper-extremity pain as well as for other NIRS research and clinical applications.

  • 7.
    D'Ascenzi, Flavio
    et al.
    Siena, Italy.
    Pelliccia, Antonio
    Rome, Italy.
    Natali, Benedetta Maria
    Siena, Italy.
    Cameli, Matteo
    Siena, Italy.
    Lisi, Matteo
    Siena, Italy.
    Focardi, Marta
    Siena, Italy.
    Padeletti, Margherita
    Siena, Italy.
    Palmitesta, Paola
    Siena, Italy.
    Corrado, Domenico
    Padua, Italy.
    Bonifazi, Marco
    Siena, Italy.
    Mondillo, Sergio
    Siena, Italy.
    Henein, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi. michael.henein@umu.se.
    Training-induced dynamic changes in left atrial reservoir, conduit, and active volumes in professional soccer players2015Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 115, nr 8, s. 1715-1723Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although left atrial (LA) enlargement is a recognized component of athlete's heart, dynamic cavity changes occurring during the training period remain to be elucidated. We aimed to investigate the adaptive changes of LA reservoir, conduit, and active volumes in elite athletes vs. controls and their response to different training loads. LA maximum, pre-P, and minimum volumes were assessed in 26 top-level athletes and 23 controls. In athletes, LA volumes were measured at pre-, mid-, end-training, and post-detraining time points using conventional 2D echocardiography. Athletes had larger maximum (27.5 +/- A 3.2 vs. 20.3 +/- A 5.8 mL/m(2), p = 0.001), pre-P (11.5 +/- A 0.9 vs. 9.8 +/- A 2.2 mL/m(2), p = 0.001), and minimum (6.6 +/- A 0.9 vs. 5.0 +/- A 1.2 mL/m(2), p < 0.001) LA indexed volumes, compared with controls. Total and passive emptying volume indices were also larger in athletes compared with controls (18.7 +/- A 3.1 vs. 15.3 +/- A 4.9 mL/m(2), p < 0.05 and 13.8 +/- A 2.9 vs. 10.5 +/- A 4.6 mL/m(2), p < 0.05, respectively), while active emptying volume was similar (p = 0.74). During training, LA maximum (p < 0.0001), pre-P (p < 0.0001), minimum (p < 0.0001), total (p < 0.005), and passive (p < 0.05) emptying volume indices progressively increased, while active emptying volume (p = 0.10) and E/e' ratio (p = 0.32) remained unchanged. After detraining, LA volume measurements were not different from pre-training ones. End-training left ventricular mass index was the only independent predictor of the respective maximum LA volume (beta = 0.74, p < 0.005). Top-level athletes exhibit a dynamic morphological and functional LA remodeling, induced by training, with an increase in reservoir and conduit volumes, but stable active volume. LA remodeling is closely associated with left ventricular adaptation to exercise and both completely regress after detraining.

  • 8.
    Elcadi, Guilherme H.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Rehabiliteringsmedicin.
    Forsman, Mikael
    Public Health Sciences, Karolinska Institute, Centre for Musculoskeletal Research, University of Gävle.
    Aasa, Ulrika
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Sjukgymnastik.
    Fahlström, Martin
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Rehabiliteringsmedicin.
    Crenshaw, Albert G.
    Department of Occupational and Public Health , University of Gävle.
    Shoulder and forearm oxygenation and myoelectric activity in patients with work related muscle pain and healthy subjects2013Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, nr 5, s. 1103-1115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We tested hypotheses of (i) reduced oxygen usage, oxygen recovery, blood flow and oxygen consumption; and (ii) increased muscle activity for patients diagnosed with work related muscle pain in comparison to healthy controls. Oxygenation was measured with near infrared spectroscopy (NIRS), and muscle activity with EMG for the extensor carpi radialis (ECR) and trapezius descendens (TD) muscles. Eighteen patients with diffuse neck-shoulder-arm pain and seventeen controls (matched in age and sex) were equipped with NIRS and EMG probes. After determining an individual’s maximum voluntary contraction (MVC) force, short term (20 sec) isometric contractions for the ECR and TD of 10%, 30%, 50% and 70% MVC generated ∆StO2% and StO2% recovery (Rslope) from NIRS, and RMS%max from EMG signals. In addition, upper arm venous (VO) and arterial (AO) occlusions generated slopes of total hemoglobin (HbTslope) and deoxyhemoglobin (HHbslope) for the resting ECR as surrogates of blood flow and oxygen consumption, respectively. Mixed Model analyses, t-tests, and Mann-Whitney test were used to assess differences between groups. There was no significant difference in MVC between groups for either muscle. Also, ∆StO2%, Rslope for either muscle, and ECR-HbTslope were not different between groups, thus our hypotheses of reduced oxygen use, recovery, and blood flow for patients were not confirmed. However, patients had a significantly lower ECR-HHbslope confirming our hypothesis of reduced consumption. Further, there was no difference in RMS%max during contractions meaning that the hypothesis of increased activity for patients was not confirmed. When taking into account the number of NIRS variables studied, differences we found between our patient group and healthy controls (i.e. in forearm oxygen consumption and shoulder oxygen saturation level) may be considered modest. Overall our findings may have been impacted by the fact that our patients and controls were similar in muscle strength, which is in contrast to previous studies.

  • 9.
    Elcadi, Guilherme H
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Forsman, Mikael
    Department for Occupational and Environmental Medicine, Public Health Sciences, Karolinska Institute.
    Crenshaw, Albert G
    Centre for Musculoskeletal Research, University of Gävle.
    The relationship between oxygenation and myoelectric activity in the forearm and shoulder muscles of males and females2011Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, nr 4, s. 647-658Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim was to investigate the relationship between oxygen saturation (StO2%) measured with near-infrared spectroscopy (NIRS) and myoelectric activity (root mean square, RMS) for the extensor carpi radialis (ECR) and trapezius muscles. Additionally, gender differences were examined for submaximal (10% - 70 % MVC) and sustained (10% MVC for 5 min) isometric contractions. Thirteen males and 15 females participated. Changes in StO2% (∆StO2%) and RMS, expressed as percentages of maximum, were calculated for each submaximal contraction. A good correlation between ∆StO2% and RMS was seen for the ECR (r = - 0.53) and a moderate correlation seen for the trapezius muscle (r = - 0.44). The ANOVA showed a significant decrease in ECR-∆StO2% over force with females demonstrating a tendency for larger changes than males. ECR-RMS increased over force with no impact of gender. For the trapezius, ∆StO2% decreased over force but was not gender dependent. Trapezius-RMS increased over force with females demonstrating a tendency for greater change than males. For the sustained contraction, ECR-StO2% changed over time but was not gender dependent. ECR-RMS increased over time with females showing a greater response than males. Trapezius-StO2% changed over time and differed between genders, i.e. males increased while females decreased. RMS increased over time similarly for both genders. In conclusion our data show that the ECR and trapezius aerobic demands during isometric contractions are negatively correlated to EMG RMS. The present study also suggests some gender specificity for forearm and shoulder myoelectric activity and oxygenation for submaximal and sustained contractions.

  • 10.
    Flodgren, Gerd
    et al.
    Centre for Musculoskeletal Research, University of Gävle, Sweden.
    Crenshaw, AG
    Centre for Musculoskeletal Research, University of Gävle, Sweden.
    Gref, Margareta
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Klinisk fysiologi.
    Fahlström, Martin
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Rehabiliteringsmedicin.
    Changes in interstitial noradrenaline, trapezius muscle activity and oxygen saturation during low-load work and recovery2009Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 107, nr 1, s. 31-42Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Both physical as well as mental demands result in an increased activity in the sympathetic nervous system (SNS) with changes in blood-pressure and heart-rate. Through local release of catecholamines, e.g. noradrenaline (NAd) SNS exerts various actions at the muscle level. The aims of this study were to investigate the effects of low-load repetitive work alone and in combination with mental demands on local muscle interstitial noradrenaline concentration [NAd]i, muscle activity and oxygenation, assessed with microdialysis, surface electromyography, and near-infrared spectroscopy, respectively. Healthy females (n = 15) were exposed to (1) 30 min repetitive work (RW) and (2) 30 min repetitive work with superimposed mental load (RWML) on two different occasions. Muscle [NAd]i and muscle activity increased significantly in response to RW, but did not increase further during RWML. For RW, [NAd]i was found to be inversely correlated to muscle activity. Oxygenation decreased significantly during work, independently of occasion. Our findings indicate that low-load work causes significantly increased trapezius muscle [NAd]i in healthy females, and short periods of superimposed mental load do not add to this increase and further, that both muscle activity and oxygenation were unaffected by the superimposed mental load.

  • 11.
    Flodgren, Gerd
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Hellström, FB
    Fahlström, Martin
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Rehabiliteringsmedicin.
    Crenshaw, AG
    Effects of 30 versus 60 minutes of low-load work on intramuscular lactate, pyruvate, glutamate, prostaglandin E2 and oxygenation in the trapezius muscle of healthy females2006Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 97, nr 5, s. 557-565Artikel i tidskrift (Refereegranskat)
  • 12.
    Hadrévi, Jenny
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Ghafouri, Bijar
    Rehabilitation Medicine, Department of Medicine and Health Sciences (IMH), Faculty of Health Sciences, Linköping University and Pain and Rehabilitation Centre, County Council of Östergötland, SE 581 85 Linköping, Sweden.
    Sjörs, Anna
    Rehabilitation Medicine, Department of Medicine and Health Sciences (IMH), Faculty of Health Sciences, Linköping University and Pain and Rehabilitation Centre, County Council of Östergötland, SE 581 85 Linköping, Sweden; Institute of Stress Medicine, Carl Skottsbergs gata 22B, SE 41319 Gothenburg, Sweden.
    Antti, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, Britt
    Rehabilitation Medicine, Department of Medicine and Health Sciences (IMH), Faculty of Health Sciences, Linköping University and Pain and Rehabilitation Centre, County Council of Östergötland, SE 581 85 Linköping, Sweden.
    Crenshaw, A. G.
    Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, Faculty of Health and Occupational Studies , University of Gävle, Umeå, Sweden.
    Gerdle, Björn
    Rehabilitation Medicine, Department of Medicine and Health Sciences (IMH), Faculty of Health Sciences, Linköping University and Pain and Rehabilitation Centre, County Council of Östergötland, SE 581 85 Linköping, Sweden.
    Hellström, Fredrik
    Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, Faculty of Health and Occupational Studies , University of Gävle, Umeå, Sweden.
    Comparative metabolomics of muscle interstitium fluid in human trapezius myalgia: an in vivo microdialysis study2013Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, nr 12, s. 2977-2989Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The mechanisms behind trapezius myalgia are unclear. Many hypotheses have been presented suggesting an altered metabolism in the muscle. Here, muscle microdialysate from healthy and myalgic muscle is analysed using metabolomics. Metabolomics analyse a vast number of metabolites, enabling a comprehensive explorative screening of the cellular processes in the muscle.

    Microdialysate samples were obtained from the shoulder muscle of healthy and myalgic subjects that performed a work and stress test. Samples from the baseline period and from the recovery period were analysed using gas chromatography-mass spectrometry (GC-MS) together with multivariate analysis to detect differences in extracellular content of metabolites between groups. Systematic differences in metabolites between groups were identified using multivariate analysis and orthogonal partial least square discriminate analysis (OPLS-DA). A complementary Mann-Whitney U test of group difference in individual metabolites was also performed.

    A large number of metabolites were detected and identified in this screening study. At baseline, no systematic differences between groups were observed according to the OPLS-DA. However, two metabolites, l-leucine and pyroglutamic acid, were significantly more abundant in the myalgic muscle compared to the healthy muscle. In the recovery period, systematic difference in metabolites between the groups was observed according to the OPLS-DA. The groups differed in amino acids, fatty acids and carbohydrates. Myristic acid and putrescine were significantly more abundant and beta-d-glucopyranose was significantly less abundant in the myalgic muscle.

    This study provides important information regarding the metabolite content, thereby presenting new clues regarding the pathophysiology of the myalgic muscle.

  • 13.
    Heiden, Marina
    et al.
    Umeå universitet, Medicinsk fakultet, Folkhälsa och klinisk medicin, Yrkesmedicin.
    Lyskov, Eugene
    Djupsjöbacka, Mats
    Hellström, Fredrik
    Crenshaw, Albert
    Effects of time pressure and precision demands during computer mouse work on muscle oxygenation and position sense2005Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 94, nr 1-2, s. 97-106Artikel i tidskrift (Refereegranskat)
  • 14.
    Henje Blom, Eva
    et al.
    Department of Clinical Neuroscience, Osher Center for Integrative Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden.
    Olsson, Erik M G
    Serlachius, Eva
    Ericson, Mats
    Ingvar, Martin
    Heart rate variability is related to self-reported physical activity in a healthy adolescent population2009Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 106, nr 6, s. 877-883Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigated whether there is a relationship between heart rate variability (HRV) versus lifestyle and risk factors for cardiovascular disease in a population of healthy adolescents. HRV is as an index of tonic autonomic activity and in adults HRV is related to lifestyle and risk factors for cardiovascular disease, but it is not known if this is the case in adolescents. HRV was registered for 4 min in sitting position in 99 healthy adolescents (age range 15 years 11 months-17 years 7 months) and repeated after 6 months. On both occasions there were significant correlations (P < 0.05) between physical activity and HRV, with respective r values: high frequency (HF) 0.26, 0.30; low frequency power (LF) 0.35, 0.29 and the standard deviation of inter-beat intervals (SDNN) 0.28, 0.37. There was no significant interaction between first and second measurements. In contrast, there were no correlations to sleeping patterns, eating habits and smoking. Risk factors for cardiovascular disease [body mass index (BMI = weight (kg)/length in m(2)), systolic blood pressure and p-glucose] did not show any repeatable significant correlations to HRV. Multiple regression models showed that physical activity was a predictor for HF, LF and SDNN in both measurements. In conclusion HF, LF and SDNN were reproducible after 6 months and were related to physical activity on both occasions.

  • 15. Kostyukov, AI
    et al.
    Kalezic, Ivana
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Serenko, SG
    Ljubisavljevic, M
    Centre for Musculoskeletal Research, National Institute for Working Life - Umeå.
    Windhorst, U
    Centre for Musculoskeletal Research, National Institute for Working Life - Umeå.
    Johansson, H
    Centre for Musculoskeletal Research, National Institute for Working Life - Umeå.
    Spreading of fatigue-related effects from active to inactive parts in the medial gastrocnemius muscle of the cat2002Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 86, nr 4, s. 295-307Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the medial gastrocnemius muscle of the decerebrate cat, the spatial spread of fatigue between active and inactive muscle parts was studied. Conditioning fatiguing stimulation (CFS) was applied to a part of the muscle to test whether it had an effect on the contraction efficiency in an unstimulated part. To exclude somato-sympathetic reflexes during CFS, a full rhizotomy of the lumbo-sacral spinal cord was performed. The same ipsilateral ventral root, either L7 or S1, was divided into seven filaments, one of which was used for the test stimulation, and four or five for CFS. The CFS consisted of 12 s sessions of distributed stimulation of five (or four) filaments at a rate of 40 s(-1), the sessions were repeated, every 40 s, 15 or more times. The test consisted of 12 s of regular stimulation at a rate of 10 s(-1), preceded and followed by a single stimulus. The tests applied just after CFS showed a strong decline of both tension and electromyogram (EMG), amounting to only [mean (SD)] 0.45 (0.18) and 0.51 (0.19) (n = 15), respectively, of the corresponding values in the tests before CFS. It thus turned out that depressive fatigue-related effects could spread within the muscle. At the same time, control reactions recorded in the lateral gastrocnemius during stimulation of its cut nerve did not change. Subsequent repetitions of the tests usually revealed a tendency towards restoration. The EMG reactions recovered more quickly than tension. The depression of EMG after CFS was accompanied by a slowing of the constituent M-waves; their latencies decreased during restoration. Distinct changes in the systemic blood pressure were observed during CFS. These changes were usually correlated well with muscle tension changes. The factors possibly underlying the observed effects may include diffusion of metabolites from active to inactive muscle fibres, lowering of the efficiency of neuro-muscular transmission due to squeezing of efferent motor terminals and changes in outer metabolite content, as well as local hypoxia due to increases in intramuscular pressure.

  • 16.
    Lindqvist, Per
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Mörner, Stellan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Henein, Michael Y
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Cardiac mechanisms underlying normal exercise tolerance: gender impact2012Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, nr 2, s. 451-459Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study is to test our hypothesis that normal exercise tolerance differs according to gender and to identify potential functional cardiac relationships, which could explain those differences. A total of 44 healthy individuals with mean age of 49 ± 12 years (28-74 years, 22 males) constituted the study cohort. All individuals underwent resting and exercise Doppler echocardiogram simultaneously with peak oxygen uptake analysis (pVO(2)). At equal pVO(2), males achieved higher peak exercise workload (p < 0.001) and females higher heart rate (p < 0.001) but the two groups maintained similar indexed left ventricular (LV) stroke volume (SV) and cardiac output. Indexed LV end-diastolic (LVDVI) and end-systolic volumes (LVSVI) were smaller in females (p < 0.001 and p < 0.01, respectively), but filling time (FT) was shorter (p < 0.001) and they had higher early diastolic (E) velocity (p = 0.004), E/E (m) (myocardial E velocity) (p < 0.001) and global longitudinal strain rate atrial velocity (GLSRa') (p = 0.02), compared to males. In males, workload (p < 0.01), LVDVI (p < 0.01), LVSVI (p < 0.05), SVI (p < 0.001) directly but LV myocardial isovolumic relaxation time (IVRTm) (p < 0.01) inversely correlated with pVO(2). In females, mitral E velocity (p < 0.01), GLSRs' (p < 0.05) positively and LVFT negatively (p < 0.05) correlated with pVO(2). In a multivariable analysis SVI in males (p < 0.01) and GLSRs' in females (p < 0.01) were the strongest predictors for pVO(2). Thus, normal exercise capacity as determined by pVO(2) is related to the indexed stroke volume in males and left atrial pressure in females. These native normal differences between genders may explain the known vulnerability of women to endurance exercise compared to men.

  • 17. Piedrahita, Hugo
    et al.
    Oksa, Juha
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Sormunen, Erja
    Rintamäki, Hannu
    Effects of cooling and clothing on vertical trajectories of the upper arm and muscle functions during repetitive light work.2008Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 104, nr 2, s. 183-91Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present study was designed to find out if cooling and/or clothing affect the vertical trajectories and muscle function of the upper arm during repetitive light work. Twelve female subjects performed a one-handed lifting task for 60 min while standing in front of a table with six target angles (30 degrees to 220 degrees ). The experiment was carried out in a climatic chamber in three different conditions: at 10 degrees C (C), at 25 degrees C (TN), and at 10 degrees C dressed in cold-protective clothing (C(p)). Skin and rectal temperatures were measured continuously. The vertical trajectories of the head, shoulder, elbow, and wrist on the right side of the body were recorded. Muscular strain (averaged EMG, a-EMG) and EMG gaps in eight muscles on the right upper arm were measured. The variation of the vertical trajectory amplitude of the upper arm measured from the elbow was significantly higher (at 200 degrees ) both at C and C(p) (50 and 25% respectively) and in shoulder (at 220 degrees angle) at C (33%) compared with TN (P < 0.05). Both C and C(p) increased a-EMG and reduced the number and duration of EMG gaps significantly in all muscles studied. In conclusion, in repetitive tasks the high mean vertical trajectory and changes in the amplitude of the trajectory of the upper arm at C and C(p) compared with TN were associated with increased muscular strain and reduced number of EMG gaps (more continuous activation of given muscle fibers). The changes in trajectories may serve as indicator of a risk for local muscle fatigue.

  • 18.
    Piedrahita, Hugo
    et al.
    Luleå University of Technology Human Work Sciences Department 97187 Luleå Sweden.
    Oksa, Juha
    Finnish Institute of Occupational Health Physical Work Capacity Team 90220 Oulu Finland.
    Rintamäki, Hannu
    Finnish Institute of Occupational Health Physical Work Capacity Team 90220 Oulu Finland.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Effect of local leg cooling on upper limb trajectories and muscle function and whole body dynamic balance2009Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, nr 3, s. 429-438Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study was designed to find out if local leg cooling affects muscle function and trajectories of the upper limb during repetitive light work as well as capability to maintain dynamic balance. Nine healthy female subjects performed repetitive lifting task with right hand for 60 min while standing in front of a table with six target angles (30 degrees -220 degrees ) and with the legs inside a container with 15 degrees C cold water (Cold condition, C) or without water (Normal condition, N). Muscle temperature of the medial aspect of the gastrocnemius, rectal, and skin temperatures were measured continuously. The trajectories of the right upper limb were recorded with a 3D motion analysis system. Muscular strain (averaged EMG, a-EMG) and EMG gaps in eight muscles of the right upper limb were measured. End point excursion depicting the ability to maintain dynamic balance was measured before and after each experiment. Leg cooling decreased significantly (P < 0.05) the muscle and the mean skin temperature in C compared with N (6.7 and 2.2 degrees C, respectively). No marked changes in the trajectories or EMG activity were observed between the different environmental conditions. The end point excursion was significantly (P < 0.05) reduced in C compared with N and a positive correlation between excursion and muscle temperature was found at the end of the working period in C. In conclusion, local leg cooling did not affect upper limb muscle function or trajectories, but ability to maintain dynamic balance was reduced.

  • 19.
    Wichardt, Emma
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Mattsson, C Mikael
    Ekblom, Björn
    Henriksson-Larsén, Karin
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Rhabdomyolysis/myoglobinemia and NSAID during 48 h ultra-endurance exercise (adventure racing)2011Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, nr 7, s. 1541-4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Our purpose is to determine whether rhabdomyolysis with myoglobinemia exists during a 48+ h adventure race and if there is a correlation with NSAID use, race time and perceived pain or exertion. Blood samples for analyses of myoglobin (Mb) were collected, and perception of exertion and pain was registered on the Borg-RPE and CR scales, from 20 subjects (3 female, 17 male) Pre-, Mid- and Post-race. Subjects were asked about NSAID use at each sampling and within 12 h pre-race. The result observed was a significant rise in Mb throughout the race, with the NSAID group (n = 6) having significantly lower Mb-Post than the no-NSAID group (n = 14). High Mb-Pre and Post correlated to shorter race time and high Mb-Pre to lower Pain-post. Race time also correlated to NSAID use, with the NSAID group having significantly longer race time than the no-NSAID group. Rhabdomyolysis with myoglobinemia, which might be reduced with NSAID use, exists during a 48+ h adventure race. Indications that high Mb-levels correlate with shorter race time and less pain, and the reasons for the NSAID groups longer race time, warrants further investigation.

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