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  • 51.
    Askling, Carl M
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tengvar, Magnus
    Saartok, Tönu
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Proximal hamstring strains of stretching type in different sports: injury situations, clinical and magnetic resonance imaging characteristics, and return to sport.2008In: The American journal of sports medicine, ISSN 1552-3365, Vol. 36, no 9, p. 1799-804Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Hamstring strains can be of at least 2 types, 1 occurring during high-speed running and the other during motions in which the hamstring muscles reach extreme lengths, as documented for sprinters and dancers. HYPOTHESIS: Hamstring strains in different sports, with similar injury situations to dancers, also show similarities in symptoms, injury location, and recovery time. STUDY DESIGN: Case series (prognosis); Level of evidence, 4. METHODS: Thirty subjects from 21 different sports were prospectively included. All subjects were examined clinically and with magnetic resonance imaging (MRI). The follow-up period lasted until the subjects returned to or finished their sport activity. RESULTS: All injuries occurred during movements reaching a position with combined extensive hip flexion and knee extension. They were located proximally in the posterior thigh, close to the ischial tuberosity. The injuries were often complex, but 83% involved the semimembranosus and its proximal free tendon. Fourteen subjects (47%) decided to end their sports activity. For the remaining 16 subjects, the median time for return to sport was 31 weeks (range, 9-104). There were no significant correlations between specific clinical or MRI parameters and time to return to sport. CONCLUSIONS: In different sports, an injury situation in which the hamstring muscles reach extensive length causes a specific injury to the proximal posterior thigh, earlier described in dancers. Because of the prolonged recovery time associated with this type of injury, correct diagnosis, based on history and palpation, and adequate information to the subject are essential.

  • 52.
    Askling, Carl M
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tengvar, Magnus
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Acute hamstring injuries in Swedish elite sprinters and jumpers: a prospective randomised controlled clinical trial comparing two rehabilitation protocols.2014In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 48, no 7, p. 532-9Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Hamstring strain is a common injury in sprinters and jumpers, and therefore time to return to sport and secondary prevention become of particular concern.

    OBJECTIVE: To compare the effectiveness of two rehabilitation protocols after acute hamstring injury in Swedish elite sprinters and jumpers by evaluating time needed to return to full participation in the training process.

    STUDY DESIGN: Prospective randomised comparison of two rehabilitation protocols.

    METHODS: Fifty-six Swedish elite sprinters and jumpers with acute hamstring injury, verified by MRI, were randomly assigned to one of two rehabilitation protocols. Twenty-eight athletes were assigned to a protocol emphasising lengthening exercises, L-protocol, and 28 athletes to a protocol consisting of conventional exercises, C-protocol. The outcome measure was the number of days to return to full training. Re-injuries were registered during a period of 12 months after return.

    RESULTS: Time to return was significantly shorter for the athletes in the L-protocol, mean 49 days (1SD±26, range 18-107 days), compared with the C-protocol, mean 86 days (1SD±34, range 26-140 days). Irrespective of protocol, hamstring injuries where the proximal free tendon was involved took a significantly longer time to return than injuries that did not involve the free tendon, L-protocol: mean 73 vs 31 days and C-protocol: mean 116 vs 63 days, respectively. Two reinjuries were registered, both in the C-protocol.

    CONCLUSIONS: A rehabilitation protocol emphasising lengthening type of exercises is more effective than a protocol containing conventional exercises in promoting time to return in Swedish elite sprinters and jumpers.

  • 53.
    Askling, Carl M
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tengvar, Magnus
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Acute hamstring injuries in Swedish elite football: a prospective randomised controlled clinical trial comparing two rehabilitation protocols.2013In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 47, no 15, p. 953-9Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Hamstring injury is the single most common injury in European professional football and, therefore, time to return and secondary prevention are of particular concern.

    OBJECTIVE: To compare the effectiveness of two rehabilitation protocols after acute hamstring injury in Swedish elite football players by evaluating time needed to return to full participation in football team-training and availability for match selection.

    STUDY DESIGN: Prospective randomised comparison of two rehabilitation protocols.

    METHODS: Seventy-five football players with an acute hamstring injury, verified by MRI, were randomly assigned to one of two rehabilitation protocols. Thirty-seven players were assigned to a protocol emphasising lengthening exercises, L-protocol and 38 players to a protocol consisting of conventional exercises, C-protocol. The outcome measure was the number of days to return to full-team training and availability for match selection. Reinjuries were registered during a period of 12 months after return.

    RESULTS: Time to return was significantly shorter for the players in the L-protocol, mean 28 days (1SD±15, range 8-58 days), compared with the C-protocol, mean 51 days (1SD±21, range 12-94 days). Irrespective of protocol, stretching-type of hamstring injury took significantly longer time to return than sprinting-type, L-protocol: mean 43 vs 23 days and C-protocol: mean 74 vs 41 days, respectively. The L-protocol was significantly more effective than the C-protocol in both injury types. One reinjury was registered, in the C-protocol.

    CONCLUSIONS: A rehabilitation protocol emphasising lengthening type of exercises is more effective than a protocol containing conventional exercises in promoting time to return in Swedish elite football.

  • 54.
    Askling, Carl Magnus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    ACUTE HAMSTRING INJURIES IN ELITE FOOTBALL: REHABILITATION - RETURN - PREVENTION2016Conference paper (Refereed)
  • 55.
    Askling, Carl Magnus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    LENGTHENING EXERCISES - THE KEY TO REHABILITATION SUCCESS?2016Conference paper (Other academic)
  • 56.
    Askling, Carl Magnus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    MANAGING RETURN TO PLAY IN PLAYERS WITH RECURRENT HAMSTRING INJURIES2016Conference paper (Refereed)
  • 57.
    Askling, Carl Magnus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Karlsson, Jon
    Sahlgrenska University Hospital, Gothenburg, Sweden.
    Malliaropoulos, N
    High-speed running type or stretching-type of hamstring injuries makes a difference to treatment and prognosis2012In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 46, no 2, p. 86-87Article in journal (Refereed)
    Abstract [en]

    The article focuses on the two distinct types of hamstring muscle strains, highlighting the applicable rehabilitation approaches. It notes that acute hamstring strains are distinguished by the injury situations, namely the high-speed running type, and the stretching type, with the former requiring shorter rehabilitation period than the latter. It cites a comparative study of two rehabilitation protocols, pointing out that rehabilitation is shorter with lengthening exercises.

  • 58.
    Askling, Carl
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    A new hamstring test to complement the common clinical examination before return to sport after injury2010In: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 18, no 12, p. 1788-1803Article in journal (Refereed)
    Abstract [en]

    PURPOSE: The aim was to introduce and evaluate the reliability and validity of an active hamstring flexibility test as a complement to common clinical examination when determining safe return to sport after hamstring injury.

    METHODS: Eleven healthy subjects (28 years) were tested on repeated occasions, and 11 athletes (21 years) with MRI-verified acute hamstring strain were tested when common clinical examination revealed no signs of remaining injury, i.e. there was no differences between the legs in palpation pain, manual strength tests, and passive straight leg raise. Flexibility, i.e. highest range of motion of three consecutive trials, was calculated from electrogoniometer data during active ballistic hip flexions and conventional passive slow hip-flexions in a supine position. A VAS-scale (0-100) was used to estimate experience of insecurity during active tests.

    RESULTS: No significant test-retest differences were observed. Intra-class correlation coefficients ranged 0.94-0.99 and coefficients of variation 1.52-4.53%. Active flexibility was greater (23%) than passive flexibility. In the athletes, the injured leg showed smaller (8%) active, but not passive, flexibility than the uninjured leg. Average insecurity estimation was 52 (range 28-98) for the injured and 0 for the uninjured leg, respectively.

    CONCLUSION: The new test showed high reliability and construct validity; furthermore, it seems to be sensitive enough to detect differences both in active flexibility and in insecurity after acute hamstring strains at a point in time when the commonly used clinical examination fails to reveal injury signs. Thus, the test could be a complement to the common clinical examination before the final decision to return to sport is made.

  • 59.
    Askling, Carl
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Saartok, Tönö
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Type of acute hamstring strain affects flexiblility, strength and time to return to pre-injury level2006In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 40, p. 40-44Article in journal (Refereed)
  • 60.
    Askling, Carl
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Schache, Anthony
    Posterior thigh pain2013In: Brukner & Khan's clinical sports medicine / [ed] Brukner & Khan, Australia: McGraw-Hill, 2013, 4, p. 594-625Chapter in book (Other academic)
  • 61.
    Askling, Carl
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tengvar, M
    Saartok, T
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Sports related hamstring strains--two cases with different etiologies and injury sites.2000In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 10, no 5, p. 304-7Article in journal (Refereed)
    Abstract [en]

    Hamstring strains are common injuries in sports. Knowledge about their etiology and localization is, however, limited. The two cases described here both had acute hamstring strains, but the etiologies were entirely different. The sprinter was injured when running at maximal speed, whereas the hamstring strain in the dancer occurred during slow stretching. Also the anatomical localizations of the injuries clearly differed. Magnetic resonance imaging (MRI) revealed pathological changes in the distal semitendinosus muscle in the sprinter and the proximal tendon of the semimembranosus muscle in the dancer. Subjectively, both athletes severely underestimated the recovery time. These case observations suggest a possible link between etiology and localization of hamstring strains.

  • 62.
    Azcarate, Laura
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Sandamas, Paul
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Gutierrez-Farewik, Elena M.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Wang, Ruoli
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Muscle contributions to body mass centre acceleration during the first stance of sprint running2019Conference paper (Refereed)
  • 63. Barnard, R J
    et al.
    Duncan, H W
    Thorstensson, Alf T
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Heart rate responses of young and old rats to various levels of exercise.1974In: Journal of applied physiology, ISSN 0021-8987, Vol. 36, no 4, p. 472-4Article in journal (Refereed)
  • 64. Begon, Mickaël
    et al.
    Dal Maso, Fabien
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Monnet, Tony
    Can optimal marker weightings improve thoracohumeral kinematics accuracy?2015In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 48, no 10, p. 2019-2025Article in journal (Refereed)
    Abstract [en]

    Local and global optimization algorithms have been developed to estimate joint kinematics to reducing soft movement artifact (STA). Such algorithms can include weightings to account for different STA occur at each marker. The objective was to quantify the benefit of optimal weighting and determine if optimal marker weightings can improve humerus kinematics accuracy. A pin with five reflective markers was inserted into the humerus of four subjects. Seven markers were put on the skin of the arm. Subjects performed 38 different tasks including arm elevation, rotation, daily-living tasks, and sport activities. In each movement, mean and peak errors in skin- vs. pins-orientation were reported. Then, optimal marker weightings were found to best match skin- and pin-based orientation. Without weighting, the error of the arm orientation ranged from 1.9° to 17.9°. With weighting, 100% of the trials were improved and the average error was halved. The mid-arm markers weights were close to 0 for three subjects. Weights of a subject applied to the others for a given movement, and weights of a movement applied to others for a given subject did not systematically increased accuracy of arm orientation. Without weighting, a redundant set of marker and least square algorithm improved accuracy to estimate arm orientation compared to data of the literature using electromagnetic sensor. Weightings were subject- and movement-specific, which reinforces that STA are subject- and movement-specific. However, markers on the deltoid insertion and on lateral and medial epicondyles may be preferred if a limited number of markers is used.

  • 65. Bergh, U
    et al.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Sjödin, B
    Hulten, B
    Piehl, K
    Karlsson, J
    Maximal oxygen uptake and muscle fiber types in trained and untrained humans.1978In: Medicine and science in sports, ISSN 0025-7990, Vol. 10, no 3, p. 151-4Article in journal (Refereed)
    Abstract [en]

    Maximal oxygen uptake (Vo2 max) was determined in 138 male and 41 female human subjects and muscle fiber composition (gastrocnemius and vastus lateralis) in 53 of the males. Highest values for Vo2 max were 7.38 1 x min-1 and 4.341 x min-1 in males and females, respectively. In relation to body weight the highest values were 94 and 77 ml x (kg x min)-1. Athletes participating in endurance events had very high Vo2 max and predominantly slow twitch (ST) fiber populations whereas weight lifters attained rather low values for Vo2 max and had a higher percentage of fast twitch (FT) fibers. Among subjects with the same fiber composition, Vo2 max was higher in the athletes than in the moderately trained. All groups taken together demonstrated a positive relationship between Vo2 max and the relative number of ST fibers (r = 0.67). For endurance and strength athletes r = 0.72 and for the moderately trained r = 0.34, both correlation coefficients being significant.

  • 66.
    Bjerkefors, Anna
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Performance and trainability in paraplegics: motor function, shoulder muscle strength and sitting balance before and after kayak ergometer training2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background

    Spinal cord injury (SCI) results in a complete or partial loss of motor and/or sensory function below the injury level. An SCI causes extensive functional impairment compelling many persons to wheelchair usage. Maintaining an adequate strength and control of trunk and shoulder muscles becomes essential, as the majority of every day tasks will be performed in a sitting position. Moreover, physical exercise is crucial to avoid risks connected with a sedentary life-style. Therefore, it becomes important to find suitable, effective, and attractive physical activities to retain and even improve motor functions achieved during rehabilitation. Ideally, such a training activity should be versatile and have the potential to improve several capacities beneficial to everyday life and thereby increase the independence of persons with SCI. Kayak paddling appears to fulfil several of the criteria for such an activity.

    Objectives

    The overall aims were to see if, and to what extent, a period of training on a modified kayak ergometer could influence functional performance as well as specific qualities, such as, shoulder muscle strength and sitting balance control in a group of postrehabilitated persons with thoracic SCI. An additional aim was to understand more about the availability of the trunk muscles in a person with a clinically complete thoracic SCI and how the trunk muscles are used to maintain upright sitting in response to balance perturbations.

    Methods

    Ten adult post-rehabilitated persons with thoracic SCI performed 30 sessions of kayak ergometer training for a 10-week period, with progressivel increased intensity and balance demand in the medio-lateral direction. Pre- and post-training measurements included performance in functional wheelchair tests, maximal voluntary shoulder muscle strength, and trunk stability in response to support-surface translations. Electromyographic (EMG) recordings from deep and superficial trunk muscles were obtained in a sub-sample of two subjects, one with a high thoracic SCI and one able-bodied person.

    Results

    here were significant improvements with training in functional performance, shoulder muscle strength, and the ability to maintain an upright sitting posture in response to balance perturbations in the group of persons with SCI. The EMG results revealed that the person with a high thoracic SCI, clinically classified as complete, was still able to activate trunk muscles below the injury, both in maximal voluntary efforts and in response to balance perturbations, but the response pattern differed from that of the able-bodied.

    Conclusions

    The improvements in test-performance observed with the kayak ergometer training in the persons with SCI should enhance their capacity to master similar challenges in everyday life, which, in turn, might lead to a greater independence. The pilot data on muscle activation highlight the importance of including examination of trunk muscle function in persons with thoracic SCI in relation to injury classification, prognosis, and training prescription.

  • 67.
    Bjerkefors, Anna
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Positive Effects of Kayak and Kayak Ergometer Training by people with Paraplegia2018Conference paper (Other academic)
    Abstract [en]

    Background Spinal cord injury (SCI) results in a complete or partial loss of motor and/or sensory function below the injury level. An SCI causes extensive functional impairment compelling many persons to wheelchair usage. Maintaining an adequate strength and control of trunk and shoulder muscles becomes essential, as the majority of every day tasks will be performed in a sitting position. Moreover, physical exercise is crucial to avoid risks connected with a sedentary life-style. Therefore, it becomes important to find suitable, effective, and attractive physical activities to retain and even improve motor functions achieved during rehabilitation. Ideally, such a training activity should be versatile and have the potential to improve several capacities beneficial to everyday life and thereby increase the independence of persons with SCI. Kayak paddling appears to fulfil several of the criteria for such an activity.

    Objectives The overall aims were to see if, and to what extent, a period of training on a modified kayak ergometer could influence functional performance as well as specific qualities, such as, shoulder muscle strength and sitting balance control in a group of post-rehabilitated persons with thoracic SCI.

    Methods Ten adult post-rehabilitated persons with thoracic SCI performed 30 sessions of kayak ergometer training for a 10-week period, with progressively increased intensity and balance demand in the medio-lateral direction. Pre- and post-training measurements included performance in functional wheelchair tests, maximal voluntary shoulder muscle strength, and trunk stability in response to support-surface translations.

    Results There were significant improvements with training in functional performance, shoulder muscle strength, and the ability to maintain an upright sitting posture in response to balance perturbations in the group of persons with SCI.

    Conclusions The improvements in test-performance observed with the kayak ergometer training in the persons with SCI should enhance their capacity to master similar challenges in everyday life, which, in turn, might lead to a greater independence.

  • 68.
    Bjerkefors, Anna
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Stakträning effektivt för ryggmärgsskadade2013In: Svensk Idrottsforskning: Organ för Centrum för Idrottsforskning, ISSN 1103-4629, Vol. 22, no 1, p. 36-40Article in journal (Other academic)
    Abstract [sv]

    En ryggmärgsskada leder till ett ökat stillasittande. Risken är då stor att drabbas av till exempel hjärt- och kärlsjukdomar. Många får också överbelastningsbesvär från skuldra och arm av ett liv i rullstol. Med högintensiv intervallträning i den nyutvecklade sittstakergometer går det att minska problemen.

  • 69.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Carpenter, M G
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Dynamic trunk stability is improved in paraplegics following kayak ergometer training.2007In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 17, no 6, p. 672-9Article in journal (Refereed)
    Abstract [en]

    The purpose of the study was to assess whether postural stability in persons with spinal cord injury (SCI) could be affected by training. Ten post-rehabilitated persons with thoracic SCI performed 30 sessions of kayak ergometer training during a 10-week period. The ergometer was modified with a balance module adjustable in the medio-lateral direction. Before and after the training period, horizontal support-surface translations were presented randomly, either in the forward or backward direction, or to the side, while subjects sat in their own wheelchairs. The platform perturbation consisted of an unpredictable initial acceleration, followed by a constant-velocity phase and a predictable deceleration. Markers were applied on the trunk and movement data were recorded in 3D. Four kinematic responses of trunk angular and linear displacement were investigated. In general, postural stability was improved after training with smaller rotational and linear displacements of the trunk observed during both predictable and unpredictable translations in all directions. Thus, the training was able to improve the ability of persons with long-standing SCI to maintain an upright sitting posture in response to externally generated balance perturbations, which should imply an increased capacity to master similar challenges to balance in everyday life.

  • 70.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Carpenter, Mark G
    Cresswell, Andrew G
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Trunk muscle activation in a person with clinically complete thoracic spinal cord injury.2009In: Journal of rehabilitation medicine : official journal of the UEMS European Board of Physical and Rehabilitation Medicine, ISSN 1651-2081, Vol. 41, no 5, p. 390-2Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: The aim of this study was to assess if, and how, upper body muscles are activated in a person with high thoracic spinal cord injury, clinically classified as complete, during maximal voluntary contractions and in response to balance perturbations. METHODS: Data from one person with spinal cord injury (T3 level) and one able-bodied person were recorded with electromyography from 4 abdominal muscles using indwelling fine-wire electrodes and from erector spinae and 3 upper trunk muscles with surface electrodes. Balance perturbations were carried out as forward or backward support surface translations. RESULTS: The person with spinal cord injury was able to activate all trunk muscles, even those below the injury level, both in voluntary efforts and in reaction to balance perturbations. Trunk movements were qualitatively similar in both participants, but the pattern and timing of muscle responses differed: upper trunk muscle involvement and occurrence of co-activation of ventral and dorsal muscles were more frequent in the person with spinal cord injury. CONCLUSION: These findings prompt further investigation into trunk muscle function in paraplegics, and highlight the importance of including motor tests for trunk muscles in persons with thoracic spinal cord injury, in relation to injury classification, prognosis and rehabilitation.

  • 71.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Jansson, A
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Shoulder muscle strength in paraplegics before and after kayak ergometer training2006In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 97, no 5, p. 613-8Article in journal (Refereed)
    Abstract [en]

    The purpose was to investigate if shoulder muscle strength in post-rehabilitated persons with spinal cord injury (SCI) was affected by kayak ergometer training and to compare shoulder strength in persons with SCI and able-bodied persons. Ten persons with SCI (7 males and 3 females, injury levels T3-T12) performed 60 min kayak ergometer training three times a week for 10 weeks with progressively increased intensity. Maximal voluntary concentric contractions were performed during six shoulder movements: flexion and extension (range of motion 65 degrees ), abduction and adduction (65 degrees ), and external and internal rotation (60 degrees ), with an angular velocity of 30 degrees s(-1). Position specific strength was assessed at three shoulder angles (at the beginning, middle and end of the range of motion) in the respective movements. Test-retests were performed for all measurements before the training and the mean intraclass correlation coefficient was 0.941 (95% CI 0.928-0.954). There was a main effect of kayak ergometer training with increased shoulder muscle strength after training in persons with SCI. The improvements were independent of shoulder movement, and occurred in the beginning and middle positions. A tendency towards lower shoulder muscle strength was observed in the SCI group compared to a matched reference group of able-bodied persons. Thus, it appears that post-rehabilitated persons with SCI have not managed to fully regain/maintain their shoulder muscle strength on a similar level as that of able-bodied persons, and are able to improve their shoulder muscle strength after a period of kayak ergometer training.

  • 72.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lindberg, Thomas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Norrbrink, Cecilia
    Department of Clinical Sciences, Karolinska Institutet Danderyd Hospital .
    Wahman, Kerstin
    Department of Neurobiology, Care Sciences and Society (NVS), Division of Neurorehabilitation, Karolinska Institutet.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of seated double-poling ergometer training on aerobic and mechanical power in paraplegics2012Conference paper (Refereed)
    Abstract [en]

    Introduction In wheelchair-dependent individuals with paraplegia, over 80 % would benefit from health-intervention programmes due to increased risks for cardiovascular diseases. One way to reduce the likelihood of secondary complications and/or to enhance physical capacity is to add structured exercise activities to the regular schedule throughout life. A seated double-poling ergometer (SDPE) has been developed and recently evaluated on a group of people with SCI. The results indicated that the SDPE appeared to be a suitable training tool; the shoulder movement was within a range of motion not conducive to musculoskeletal injury and it provided a large range of controllable intensities enabling both endurance and strength training.

    Purpose To study if regular interval training on a SDPE can increase physical capacity and hence improve performance towards maximal level with safety in individuals with spinal cord injury.

    Methods Thirteen healthy wheelchair users (8 M, 5 F; 47 ± 12 years, 1.75 ± 0.08 m, 67.9 ± 10.2 kg) with SCI levels ranging from T5 to L1, volunteered for the study. Years post injury varied from 3 to 35. All subjects performed 30 sessions of SDPE training during 10 weeks. Each session lasted approximately 55 min, and included a warm-up, interval training (15 s – 3 min work and 15 s – 2 min rest) and a cool-down. The intensity of the intervals was determined to lead up to 70 – 100 % of peak heart rate. Sub-maximal and maximal double-poling ergometer tests were performed before and after this training period. Oxygen uptake was measured using the Douglas Bag system. Three-dimensional kinematics were recorded using an optoelectronic system. 

    Results Significant improvements after training were observed in oxygen uptake (23 %), ventilation (21 %) and blood lactate (22 %) during maximal exertion exercises (Table 1). Mean power per stroke and peak pole force increased with 15 % and 24 %, respectively. At sub-maximal level, significantly lower values were observed in ventilation (-13 %) and blood lactate (-25 %).

    Conclusion Regular interval training on the seated double-poling ergometer (SDPE) increased oxygen uptake and power out-put and can be recommended for people with paraplegia below T5 level due to SCI. Despite the high intensity training in this study, no overload symptoms were reported. On the contrary, certain types of musculoskeletal and neuropathic pain seem to benefit from training on the SDPE.

  • 73.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lindberg, Thomas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Norrbrink, Cecilia
    Department of Clinical Sciences, Karolinska Institutet Danderyd Hospital .
    Wahman, Kerstin
    Department of Neurobiology, Care Sciences and Society (NVS), Division of Neurorehabilitation, Karolinska Institutet.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of seated double-poling ergometer training on oxygen uptake, upper-body muscle strength and motor performance in paraplegics2012Conference paper (Refereed)
    Abstract [en]

    Background:  In wheelchair-dependent individuals with paraplegia, over 80 % would benefit from health-intervention programmes due to increased risks for cardiovascular diseases. One way to reduce the likelihood of secondary complications and/or to enhance physical capacity is to add structured exercise activities throughout life.

    Objective:  To study the effects of seated double-poling ergometer (SDPE) training on aerobic capacity, upper-body muscle strength, and cross-over effects on functional performance.   

    Methods: Thirteen individuals with paraplegia performed 30 sessions of SDPE training during 10 weeks. Before and after the training period a) oxygen uptake was measured using the Douglas Bag system during sub-maximal and maximal double-poling ergometer tests, b) trunk, shoulder and elbow muscle strength measurements were performed during maximal voluntary contractions using an isokinetic dynamometer and c) functional tests in wheelchair were performed included; sit-and-reach test, propelling 15 m on a level surface, propelling 50 m up a 3º incline, and propelling 6 min on a 200 m indoor track. Test-retests were performed for all tests before the training began.

    Results: The average intra-class correlation coefficient for test-retest values was 0.91 (SD 0.07). Significant improvements after training were observed in oxygen uptake (22.7 %), ventilation (20.7 %) and blood lactate (22.0 %) during maximal exertion exercises. At sub-maximal level, significantly lower values were observed in ventilation (-12.8 %) and blood lactate (-25.0 %). Maximal isometric trunk muscle strength (17.0 %) and maximal isokinetic shoulder muscle strength (4.4 %) in flexion and extension improved after training. There were significant improvements in sit-and-reach test in forward directions (7.8 %) and in 15 m sprint test (5.2 %).     

    Conclusion: Regular interval training on the SPDE was effective for individuals with paraplegia to improve aerobic capacity and upper-body muscle strength. Some cross-over effects on functional performance were also shown. Furthermore, the training did not cause any overload symptoms.

     

  • 74.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Nordlund Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Josefsson, Karin
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Deep and superficial abdominal muscle activation during trunk stabilization exercises with and without instruction to hollow.2010In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 15, no 5, p. 502-7Article in journal (Refereed)
    Abstract [en]

    The deepest muscle of the human ventro-lateral abdominal wall, the Transversus Abdominis (TrA), has been ascribed a specific role in spine stabilization, which has motivated special core stability exercises and hollowing instruction to specifically involve this muscle. The purpose here was to evaluate the levels of activation of the TrA and the superficial Rectus Abdominis (RA) muscles during five common stabilization exercises performed in supine, bridging and four-point kneeling positions, with and without instruction to hollow, i.e. to continuously pull the lower part of the abdomen towards the spine. Nine habitually active women participated and muscle activity was recorded bilaterally from TrA and RA with intramuscular fine-wire electrodes introduced under the guidance of ultrasound. Results showed that subjects were able to selectively increase the activation of the TrA, isolated from the RA, with the specific instruction to hollow and that side differences in the amplitude of TrA activity, related to the asymmetry of the exercises, remained even after the instruction to hollow. The exercises investigated caused levels of TrA activation from 4 to 43% of that during maximal effort and can thus be used clinically to grade the load on the TrA when designing programs aiming at training that muscle.

  • 75.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Rosén, Johanna S
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Three-Dimensional Kinematics and Power Output in Elite Para-Kayakers and Elite Able-Bodied Flat-Water Kayakers.2019In: Journal of Applied Biomechanics, ISSN 1065-8483, E-ISSN 1543-2688, p. 93-100Article in journal (Refereed)
    Abstract [en]

    Trunk, pelvis and leg movement are important for performance in sprint kayaking. Para-kayaking is a new Paralympic sport in which athletes with trunk and/or leg impairment compete in three classification groups. The purpose of this study was to identify how physical impairments impact on performance by examining: differences in three-dimensional joint range of motion (RoM) between 10 (4 females, 6 males) elite able-bodied kayakers and 41 (13 females, 28 males) elite para-kayakersfrom the three classification groups, and which joint angles were correlated with power output during high intensity kayak ergometer paddling. There were significant differences in RoM between the able-bodied kayakers and the three para-kayak groups for the shoulders (flexion, rotation: able-bodied kayakers<para-kayakers), trunk and pelvis (rotation: able-bodied kayakers>para-kayakers) and legs (hip, knee, ankle flexion: able-bodied kayakers>para-kayakers) during paddling. Furthermore, athletes with greater impairment exhibited lower trunk and leg RoM compared to those with less impairment. Significant positive correlations were observed for both males and females between power output and peak shoulder and trunk flexion, trunk and pelvis rotation RoM and hip, knee and ankle flexion RoM. This information is important for understanding how key kinematic and kinetic variables for para-kayaking performance vary between athletes from different classification groups.

  • 76.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Squair, J W
    Malik, R
    Lam, T
    Chen, Z
    Carpenter, M G
    Diagnostic accuracy of common clinical tests for assessing abdominal muscle function after motor-complete spinal cord injury above T6.2015In: Spinal Cord, ISSN 1362-4393, E-ISSN 1476-5624, Vol. 53, p. 114-119Article in journal (Refereed)
    Abstract [en]

    Study design:Diagnostic study.Objectives:The objective of this study was to compare patterns of electromyography (EMG) recordings of abdominal muscle function in persons with motor-complete spinal cord injury (SCI) above T6 and in able-bodied controls, and to determine whether manual examination or ultrasound measures of muscle activation can be accurate alternatives to EMG.Setting:Research center focused on SCI and University laboratory, Vancouver, Canada.Methods:Thirteen people with SCI (11 with American Spinal Injury Association Impairment Scale (AIS) A and 2 AIS B; C4-T5), and 13 matched able-bodied participants volunteered for the study. Participants completed trunk tasks during manual examination of the abdominal muscles and then performed maximal voluntary isometric contractions, while EMG activity and muscle thickness changes were recorded. The frequency of muscle responses detected by manual examination and ultrasound were compared with detection by EMG (sensitivity and specificity).Results:All individuals with SCI were able to elicit EMG activity above resting levels in at least one abdominal muscle during one task. In general, the activation pattern was task specific, confirming voluntary control of the muscles. Ultrasound, when compared with EMG, showed low sensitivity but was highly specific in its ability to detect preserved abdominal muscle function in persons with SCI. Conversely, manual examination was more sensitive than ultrasound but showed lower specificity.Conclusion:The results from this study confirm preserved voluntary abdominal muscle function in individuals classified with motor-complete SCI above T6 and highlight the need for further research in developing more accurate clinical measures to diagnose the level of trunk muscle preservation in individuals with SCI.Spinal Cord advance online publication, 25 November 2014; doi:10.1038/sc.2014.202.

  • 77.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Squair, J W
    Malik, R
    Lam, T
    Chen, Z
    Carpenter, M G
    Response to 'Diagnostic accuracy of common clinical tests for assessing abdominal muscle function after motor-complete spinal cord injury above T6'.2015In: Spinal Cord, ISSN 1362-4393, E-ISSN 1476-5624, Vol. 53, no 12, p. 892-892Article in journal (Other academic)
  • 78.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Squair, Jordan
    Chen, Zhen
    Lam, Tania
    Carpenter, Mark
    Postural control in individuals with spinal cord injury: Training, functional performance, and mechanisms2014Conference paper (Refereed)
    Abstract [en]

    BACKGROUND AND AIM: Postural control in sitting is essential for people with spinal cord injury (SCI). Studies indicate that impaired postural control is related to decreased propulsion efficiency, respiratory dysfunction and development of pressure sores. Despite this, there is limited knowledge on the best methods to rehabilitate postural control in people with SCI and if and by what mechanism persons with high-thoracic SCI may improve their postural control. Thus, our aims were to 1) determine the efficacy of targeted rehabilitation towards postural control in people with SCI, and 2) investigate the neural mechanisms behind any observed improvements.

     

    METHODS: Persons with SCI completed 30 sessions over 10 weeks of a) seated double poling ergometer (SDP) training (n=13) or b) kayak ergometer (KE) training (n=10). Before and after functional tests were performed and included: sit-and-reach tests, propelling 15m on a level surface and propelling 50m up a 3º incline. Additionally, subjects sat in their wheelchair while support-surface translations were presented (KE) or performed isometric maximal voluntary contractions in a dynamometer during trunk flexion and extension (SDP). To investigate neural mechanisms of postural control improvement, electromyographic (EMG) responses in the ventral postural muscles to maximal voluntary contractions and transcranial magnetic stimulation (TMS) were assessed in 5 individuals with motor complete SCI above T6.

     

    RESULTS: Postural stability was improved after KE and SDP training demonstrated by smaller rotational and linear displacements of the trunk during support surface translations (KE) and improved postural muscle strength (SDP). There were also significant improvements in propelling tasks and in the sit-and-reach tasks, both in the sagittal plane (SDP) as well as in lateral directions (KE). All persons with motor complete SCI above T6 (n=5) were able to elicit task specific EMG activity in the ventral postural muscles during maximal voluntary contractions despite their clinical classification. Motor evoked potentials were also recorded in each individual´s ventral postural muscles in response to TMS, confirming corticospinal pathway preservation.

     

    CONCLUSIONS: Postural control, upright sitting, and functional performance in daily life activities can be improved in people with high-thoracic SCI during regular exercising, such as kayaking and seated double poling ergometer training. The neural mechanism behind the improvement is in part due to partial preservation of the corticospinal pathways to the postural muscles as confirmed by the use EMG and TMS.

     

  • 79.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Squair, Jordan W
    Chua, Romeo
    Lam, Tania
    Chen, Zhen
    Carpenter, Mark G
    Assessment of abdominal muscle function in individuals with motor-complete spinal cord injury above T6 in response to transcranial magnetic stimulation.2015In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 47, no 2, p. 138-146Article in journal (Refereed)
    Abstract [en]

    Objective: To use transcranial magnetic stimulation and electromyography to assess the potential for preserved function in the abdominal muscles in individuals classified with motor-complete spinal cord injury above T6. Subjects: Five individuals with spinal cord injury (C5-T3) and 5 able-bodied individuals. Methods: Transcranial magnetic stimulation was delivered over the abdominal region of primary motor cortex during resting and sub-maximal (or attempted) contractions. Surface electromyography was used to record motor-evoked potentials as well as maximal voluntary (or attempted) contractions in the abdominal muscles and the diaphragm. Results: Responses to transcranial magnetic stimulation in the abdominal muscles occurred in all spinal cord injury subjects. Latencies of muscle response onsets were similar in both groups; however, peak-to-peak amplitudes were smaller in the spinal cord injury group. During maximal voluntary (or attempted) contractions all spinal cord injury subjects were able to elicit electromyography activity above resting levels in more than one abdominal muscle across tasks. Conclusion: Individuals with motor-complete spinal cord injury above T6 were able to activate abdominal muscles in response to transcranial magnetic stimulation and during maximal voluntary (or attempted) contractions. The activation was induced directly through corticospinal pathways, and not indirectly by stretch reflex activations of the diaphragm. Transcranial magnetic stimulation and electromyography measurements provide a useful method to assess motor preservation of abdominal muscles in persons with spinal cord injury.

  • 80.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Rosén, Johanna S
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Zakaria, Pascal
    Swedish School of Sport and Health Sciences, GIH.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Three-dimensional kinematic analysis and power output of elite flat-water kayakers.2018In: Sports Biomechanics, ISSN 1476-3141, E-ISSN 1752-6116, Vol. 17, no 3, p. 414-427Article in journal (Refereed)
    Abstract [en]

    The purpose was to examine power output and three-dimensional (3D) kinematic variables in the upper limbs, lower limbs and trunk in elite flat-water kayakers during kayak ergometer paddling. An additional purpose was to analyse possible changes in kinematics with increased intensity and differences between body sides. Six male and four female international level flat-water kayakers participated. Kinematic and kinetic data were collected during three tasks; low (IntL), high (IntH) and maximal (IntM) intensities. No differences were observed in any joint angles between body sides, except for shoulder abduction. Significantly greater range of motion (RoM) values were observed for IntH compared to IntL and for IntM compared to IntL in trunk and pelvis rotation, and in hip, knee and ankle flexion. The mean maximal power output was 610 ± 65 and 359 ± 33 W for the male and female athletes, respectively. The stroke frequencies were significantly different between all intensities (IntL 59.3 ± 6.3; IntH 108.0 ± 6.8; IntM 141.7 ± 18.4 strokes/min). The results showed that after a certain intensity level, the power output must be increased by other factors than increasing the joint angular RoM. This information may assist coaches and athletes to understand the relationship between the movement of the kayaker and the paddling power output.

  • 81.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of kayak ergometer training on motor performance in paraplegics.2006In: International Journal of Sports Medicine, ISSN 0172-4622, E-ISSN 1439-3964, Vol. 27, no 10, p. 824-9Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to assess the effects of kayak ergometer training on functional tests performed in wheelchair by persons with spinal cord injury. Ten post-rehabilitated persons with thoracic spinal cord injury volunteered for the study and performed 30 sessions of kayak ergometer training during a 10-week period. The ergometer was modified with an additional balance demand in the medio-lateral direction. Before and after the training period the subjects performed functional tests in the wheelchair: Sit-and-reach tests (distance), mounting a platform, transfer to a bench (height), propelling the wheelchair: 5 m on the rear wheels; in a figure-8; 15 m on a level surface and 50 m on a 3 degrees inclined surface (time). Test-retests were performed for all tests before the training began. A written questionnaire was distributed to evaluate the subjective experiences of the training. The test-retest resulted in coefficient of variation of 1.3 - 4.6 %. There were significant improvements in sit-and-reach (14 %), mounting a platform (7 %), transfer to a bench (10 %), propelling on level (3 %), and inclined surface (6 %). Furthermore, the training, did not cause any shoulder pain or other problems. This, and the positive subjective experience expressed by the subjects after the training indicate that this type of training is a suitable activity for persons with thoracic spinal cord injury.

  • 82.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tinmark, Fredrik
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, The Laboratory of Applied Sports Science (LTIV).
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Seated Double-Poling Ergometer Performance of Individuals with Spinal Cord Injury - A New Ergometer Concept for Standardized Upper Body Exercise2013In: International Journal of Sports Medicine, ISSN 0172-4622, E-ISSN 1439-3964, Vol. 34, no 2, p. 176-182Article in journal (Refereed)
    Abstract [en]

    This study aimed to evaluate biomechanics during seated double-poling exercises in individuals with spinal cord injury (SCI) and to compare these with those of able-bodied persons (AB). 26 participants volunteered for the study; 13 with SCI (injury levels C7-T12), and 13 AB. A seated double-poling ergometer (SDPE) was developed. 3-dimensional kinematics was measured and piezoelectric force sensors were used to register force in both poles for calculation of power during incremental intensities. Significantly lower power outputs, (143.2 ± 51.1 vs. 198.3 ± 74.9 W) and pole forces (137.1 ± 43.1 vs. 238.2 ± 81.2 N) were observed during maximal effort in SCI compared to AB. Sagittal upper trunk range of motion increased with intensity and ranged from 6.1–34.8 ° for SCI, and 6.9–31.3 ° for AB, with larger peak amplitudes in flexion for AB (31.4 ± 12.9 °) compared to SCI (10.0 ± 8.0 °). All subjects with SCI were able to exercise on the SDPE. Upper body kinematics, power and force outputs increased with intensity in both groups, but were in general, lower in SCI. In conclusion, the SDPE could be successfully used at low to high work intensities enabling both endurance and strength training for individuals with SCI

  • 83.
    Bojsen-Møller, Emil
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Boraxbekk, Carl-Johan
    Copenhagen University Hospital, Hvidovre, Denmark.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Blom, Victoria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Sport Psychology research group.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Relationships between Physical Activity, Sedentary Behaviour and Cognitive Functions in Office Workers.2019In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 16, no 23, article id E4721Article in journal (Refereed)
    Abstract [en]

    Increasing evidence from animal experiments suggests that physical activity (PA) promotes neuroplasticity and learning. For humans, most research on the relationship between PA, sedentary behaviour (SB), and cognitive function has relied on self-reported measures of behaviour. Office work is characterised by high durations of SB combined with high work demands. While previous studies have shown that fitter office workers outperform their less fit colleagues in cognitive tests, the importance of PA and SB remains unknown. This study investigated associations between objectively measured PA and SB, using hip-worn accelerometers, and cognitive functions in 334 office workers. Time spent in moderate-to-vigorous PA (MVPA) was not associated with any cognitive outcome. However, time spent in SB tended to be positively associated with words recalled in free recall (β = 0.125). For the least fit participants, the average length of MVPA bouts was favourably related to Stroop performance (β = -0.211), while for the fitter individuals, a longer average length of MVPA bouts was related to worse recognition (β = -0.216). While our findings indicate that the length of MVPA bouts was associated with better Stroop performance in the least fit participants, our findings do not support the notion that more time spent in MVPA or less time in SB is associated with better cognitive function.

  • 84. Bonnard, M
    et al.
    Sirin, A V
    Oddsson, L
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Different strategies to compensate for the effects of fatigue revealed by neuromuscular adaptation processes in humans.1994In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 166, no 1, p. 101-5Article in journal (Refereed)
    Abstract [en]

    An initially submaximal hopping task was maintained with the same global power output until it became the maximal performance; since there was no decrease in performance, any change in behavior occurring with fatigue characterizes the strategies allowing to compensate for the effects of fatigue. In a prolonged hopping task, fatigue is likely to be most prominent in the ankle extensor muscles since they are the main contributors to vertical propulsion in the hop. With fatigue, all subjects landed with more flexed knees and with an increased activity in the biarticular rectus femoris muscle indicating some compensation between the knee and ankle joint. Furthermore, two different strategies appeared to further compensate for the important fatigue of the ankle extensor muscles: one was organized across joints and consisted in a heavier reliance of the knee extensor vastus lateralis, and the other was organized within the fatigued joint and consisted in an earlier preactivation of the gastrocnemius. As a consequence, two different adaptations of the ground reaction force profiles appeared at the end of the session; each being related to one of these two strategies.

  • 85.
    Bratland-Sanda, Solfrid
    et al.
    University College of Southeast Norway.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Best, James
    Jaeren Psychiatric Center, Norway.
    Høegmark, Simon
    Naturama Museum, Denmark.
    Roessler, Kirsten Kaya
    University of Southern Denmark.
    The use of physical activity, sport and outdoor life as tools of psychosocial intervention: the Nordic perspective2019In: Sport in Society: Cultures, Media, Politics, Commerce, ISSN 1743-0437, E-ISSN 1743-0445, Vol. 22, no 4, SI, p. 654-670Article in journal (Refereed)
    Abstract [en]

    The core values in the Nordic welfare model are health equality and social inclusion. Individuals with mental disorders and/or a history of substance use disorder are often excluded from the core value of equality. Psychosocial interventions such as physical activity and outdoor life can have several benefits for those suffering from mental disorders. Firstly, such interventions can have therapeutic effects. Secondly, they show benefits for somatic health and the risk of lifestyle-related diseases. Finally, they can provide an environment for experiencing self-efficacy, lead to improved quality of life, and promote the development and building of social relationships. This paper provides a critical review of current evidence for physical activity and outdoor life as psychosocial interventions in psychiatric and substance misuse treatment, with specific examples from Norway, Sweden and Denmark.

  • 86.
    Brink-Elfegoun, Thibault
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Holmberg, Hans-Christer
    Nordlund Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Neuromuscular and circulatory adaptation during combined arm and leg exercise with different maximal work loads.2007In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 101, no 5, p. 603-11Article in journal (Refereed)
    Abstract [en]

    Cardiopulmonary kinetics and electromyographic activity (EMG) during exhausting exercise were measured in 8 males performing three maximal combined arm+leg exercises (cA+L). These exercises were performed at different rates of work (mean+/-SD; 373+/-48, 429+/-55 and 521+/-102 W) leading to different average exercise work times in all tests and subjects. VO2 reached a plateau versus work rate in every maximal cA+L exercise (range 6 min 33 s to 3 min 13 s). The three different exercise protocols gave a maximal oxygen consumption (VO2MAX) of 4.67+/-0.57, 4.58+/-0.52 and 4.66+/-0.53 l min(-1) (P=0.081), and a maximal heart rate (HRmax) of 190+/-6, 189+/-4 and 189+/-6 beats min(-1) (P=0.673), respectively. Root mean square EMG (EMGRMS) of the vastus lateralis and the triceps brachii muscles increased with increasing rate of work and time in all three cA+L protocols. The study demonstrates that despite different maximal rates of work, leading to different times to exhaustion, the circulatory adaptation to maximal exercise was almost identical in all three protocols that led to a VO2 plateau. The EMG(RMS) data showed increased muscle recruitment with increasing work rate, even though the HRmax and VO2MAX was the same in all three cA+L protocols. In conclusion, these findings do not support the theory of the existence of a central governor (CG) that regulates circulation and neuronal output of skeletal muscles during maximal exercise.

  • 87. Broström, Eva
    et al.
    Nordlund Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Cresswell, Andrew G
    Plantar- and dorsiflexor strength in prepubertal girls with juvenile idiopathic arthritis.2004In: Archives of Physical Medicine and Rehabilitation, ISSN 0003-9993, E-ISSN 1532-821X, Vol. 85, no 8, p. 1224-30Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To compare lower-leg strength of young girls with polyarticular juvenile idiopathic arthritis (JIA) with that of healthy, age-matched controls. DESIGN: Isometric and isokinetic strength tests of the plantar- and dorsiflexors. All strength measures were made at an ankle angle of 90 degrees. Isokinetic plantar- and dorsiflexor measures were made at 15 degrees/s during shortening (concentric) and lengthening (eccentric) actions. SETTING: Strength testing laboratory. PARTICIPANTS: Ten prepubertal girls diagnosed with JIA and 10 healthy girls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Isometric and isokinetic plantar- and dorsiflexor strength. RESULTS: Isometric plantar- and dorsiflexion torques were significantly lower (48% and 38% respectively; P<.05) for the children with JIA than for the controls. The JIA group also produced lower shortening plantarflexion torques (52%, P<.05). Lengthening plantarflexor torques did not differ significantly between the 2 groups (P<.05). Controls were stronger than the JIA group for both shortening and lengthening maximal dorsiflexor actions (P<.05). All children were 4 to 5 times stronger in plantarflexion than in dorsiflexion. CONCLUSIONS: Girls with JIA had significantly less plantar- and dorsiflexor strength than age-matched, healthy peers. The reduced strength of children with JIA is likely to affect function in daily activities and probably contributes to reduced levels of physical activity.

  • 88. Calbet, José A L
    et al.
    Losa-Reyna, José
    Peralta, Rafael Torres
    Rasmussen, Peter
    Ponce-González, Jesús Gustavo
    Sheel, A William
    de la Calle-Herrero, Jaime
    Grau, Amelia Guadalupe
    Morales-Alamo, David
    Fuentes, Teresa
    Rodríguez-García, Lorena
    Siebenmann, Christoph
    Boushel, Robert
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lundby, Carsten
    Limitations to oxygen transport and utilisation during sprint exercise in humans: evidence for a functional reserve in muscle O2 diffusing capacity.2015In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 593, no 20, p. 4649-4664Article in journal (Refereed)
    Abstract [en]

    KEY POINTS SUMMARY: Severe acute hypoxia reduces sprint performance. Muscle VO2 during sprint exercise in normoxia is not limited by O2 delivery, O2 off-loading from haemoglobin or structure-dependent diffusion constraints in the skeletal muscle of young healthy men. A large functional reserve in muscle O2 diffusing capacity exists and remains available at exhaustion during exercise in normoxia, which is recruited during exercise in hypoxia. During whole-body incremental exercise to exhaustion in severe hypoxia leg VO2 is primarily dependent on convective O2 delivery and less limited by diffusion constraints than previously thought. The kinetics of O2 off-loading from haemoglobin does not limit VO2 peak in hypoxia. Our results indicate that the limitation to VO2 during short sprints resides in mechanisms regulating mitochondrial respiration.

    ABSTRACT: To determine the contribution of convective and diffusive limitations to VO2 peak during exercise in humans oxygen transport and haemodynamics were measured in eleven men (22 ± 2 years) during incremental (IE) and 30-s all-out sprints (Wingate test, WgT), in normoxia (Nx, PI O2 :143 mmHg) and hypoxia (Hyp, PI O2 :73 mmHg). Carboxyhaemoglobin (COHb) was increased to 6-7% before both WgTs to left-shift the oxyhaemoglobin dissociation curve. Leg VO2 was measured by the Fick method, and leg blood flow (BF) with thermodilution and muscle O2 diffusing capacity (DMO2 ) was calculated. In the WgT mean power output, leg BF, leg O2 delivery and leg VO2 were 7, 5, 28 and 23% lower in Hyp than Nx (P < 0.05), however, peak WgT DMO2 was higher in hypoxia (51.5 ± 9.7) than Nx (20.5 ± 3.0 ml min(-1) mmHg(-1) , P < 0.05). Despite a similar PaO2 (33.3 ± 2.4 and 34.1 ± 3.3 mmHg), mean capillary PO2 (16.7 ± 1.2 and 17.1 ± 1.6 mmHg), and peak perfusion during IE and WgT in Hyp, DMO2 and leg VO2 were 12 and 14% higher during WgT than IE in Hyp (both, P < 0.05). DMO2 was apparently insensitive to COHb (COHb: 0.7 vs 7%, in IE Hyp and WgT Hyp). At exhaustion, the Y equilibration index was well above 1.0 in both conditions, reflecting greater convective than diffusive limitation to the O2 transfer both in Nx and Hyp. In conclusion, muscle VO2 during sprint exercise is not limited by O2 delivery, the O2 off-loading from haemoglobin or structure-dependent diffusion constraints in the skeletal muscle. These findings reveal a remarkable functional reserve in muscle O2 diffusing capacity. This article is protected by copyright. All rights reserved.

  • 89.
    Cardinale, Daniele A.
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, The Laboratory of Applied Sports Science (LTIV).
    Cardinale, Marco
    Comparative multiple sensor approach for power calculation in loaded squat jump and power clean2013In: Comparative multiple sensor approach for power calculation in loaded squat jump and power clean, 2013Conference paper (Refereed)
    Abstract [en]

    Introduction

    Power output is a critical component of athletic performance (McGuigan et al., 2012); therefore, strength and conditioning specialists are nowadays employed to help athletes increase the power-generating capacity in specific motor tasks. Due to the widespread need to assess power output in common strength training exercises, the development and validation of various assessment approaches has led to studies aimed at identifying the external optimal load (OL) to maximize power output (Cormie et al., 2007). The aim of this study was to compare conventionally used linear position transducer and force plate based methods with a new methodology for calculation of peak power (PP) and average power (AP) output in conjunction with the load-power relationship.

    Methods

    Nineteen male elite athletes performed loaded squat jump (LSJ) and power clean (PC) with different external loads to determine the load/power relationship. Nine methods were used simultaneously in data collection: vertical ground reaction force (VGRF), ground reaction force (GRF) i.e. vertical, anterio-posterior and medio-lateral reaction force components, 1 linear encoder (1Encoder), 1 linear position transducer (1LPT), 1LPT and VGRF (1LPT+VGRF), 2 linear position transducers (2LPTs), 2LPTs and VGRF (2LPTs+VGRF), 5 linear position transducers (5LPTs), 5LPTs and GRF (5LPTs+GRF; novel method). Power output was calculated for each lift according to the sensor or sensors simultaneously used and the results were compared.

    Results

    Power output calculated separately with LPTs and GRF method differed significantly from combined methods such as 1LPT+VGRF, 2LPTs+VGRF, and 5LPTs+GRF (novel method). The optimal load in LSJ and PC with respect to PP output was identified at loads between 30 and 50% of their body mass (bm), respectively; and with respect to AP output equal to loads between 85 and 75% of bm, respectively.

    Discussion

    This study indicates that test methodology influences the results of the power output and the load–power relationship in LSJ and PC exercises. The results of this study suggest the possibility that the combined methods provide a better representation of muscle power generation during dynamic movements involving the non-linear trajectories of the barbell than kinematic or kinetic methods alone.

    References

    Cormie, P., McBride, J. M., & McCaulley, G. O. (2007). J Appl Biomech, 23(2), 103-118. McGuigan. (2012). Strength and Power Assessment Protocols. Physiological Tests for Elite Athletes (2nd ed., pp. 207-230). Stanningley Leeds, United Kingdom: Human Kinetics.

  • 90. Carlson, H
    et al.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Zomlefer, M R
    Motor responses in the human trunk due to load perturbations.1981In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 111, no 2, p. 221-3Article in journal (Refereed)
  • 91. Carlson, H
    et al.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lumbar back muscle activity during locomotion: effects of voluntary modifications of normal trunk movements.1988In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 133, no 3, p. 343-53Article in journal (Refereed)
    Abstract [en]

    The mechanisms of adaptation of the trunk to changed mechanical conditions were studied during locomotion in man. The myoelectrical (EMG) activity in lumbar back muscles and the movements of the trunk were recorded in nine healthy subjects during walking and running on a motor-driven treadmill. Two different types of voluntary modifications of the movement pattern were used: (1) The trunk was kept in an extreme forward or backward tilted position. In both these situations the basic EMG pattern with two periods of activity per stride cycle was maintained during walking, whereas a major shift relative to the stride cycle (25% of the stride cycle duration) occurred in running with the trunk tilted backwards. The synchrony of the back muscle activation at both sides increased when locomotion was performed with the trunk tilted forwards. The relative duration of the EMG bursts was similar to normal locomotion and corresponded to 15-26% of the stride cycle duration in walking and 23-37% in running. (2) In the other type of modification the subjects were instructed to exaggerate the angular trunk movements either in the sagittal or in the frontal plane. The basic EMG pattern and phase relationships remained in most cases unchanged. One exception was running with exaggerated lateral movements, in which only one period of back muscle activity per stride cycle was observed. The relative duration of the bursts was longer in trials with exaggerated trunk movements as compared to normal locomotion. In walking and running with the trunk tilted forwards or backwards the lumbar back muscles were not always involved as prime movers of the trunk. This was in contrast to the more dynamic situations, in which the back muscle activity appeared to be directly involved in braking and reversing the exaggerated trunk movements.

  • 92.
    Carlsson, Magnus
    et al.
    Dalarna University.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Dalarna University.
    Hellström, John
    Halmstad University.
    Tinmark, Fredrik
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Carlsson, Tomas
    Dalarna University.
    The effect of ball temperature on ball speed and carry distance in golf drives2019In: Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, ISSN 1754-3371, Vol. 233, no 2, p. 186-192Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the effect of ball temperature on impact ball speed and carry distance during golf drives in a blind randomized test design. The balls were exposed to a temperature-controlled environment (4?°C, 18?°C, 32?°C, and 46?°C) for 24?h prior to the test and each temperature group consisted of 30 balls. The 120 drives were performed by an elite male golfer (handicap: 0.0) in an indoor driving range. All drives were measured by a Doppler-radar system to determine the club-head speed, launch angle, spin rate, ball speed, and carry distance. Differences between the groups were investigated using a one-way analysis of variance. The results indicated that ball-speed and carry-distance differences occurred within the four groups (p?<?0.001 and p?<?0.01, respectively). The post hoc analyses showed that the ball temperatures of 18?°C and 32?°C had greater ball speeds and carry distances than balls at 4?°C and 46?°C (all p?<?0.05). The intervals for the between-group differences were 0.6?0.7?m?s?1 and 2.9?3.9?m for ball speed and carry distance, respectively. Hence, the results showed that ball temperature influences both the ball speed and the carry distance. Based on the findings in this study, standardization of ball temperature should be factored into governing body regulation tests for golf equipment.

  • 93.
    Carlsson, Tomas
    et al.
    Högskolan Dalarna.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Högskolan Dalarna.
    Hellström, John
    Svenska golfförbundet.
    Tinmark, Fredrik
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Carlsson, Magnus
    Högskolan Dalarna.
    The effect of ball temperature on ball speed and carry distance in golf drives2018Conference paper (Other academic)
    Abstract [en]

    THE EFFECT OF BALL TEMPERATURE ON BALL SPEED AND CARRY DISTANCE IN GOLF DRIVES Carlsson, T.1, Nilsson, J.1,2, Hellström, J.3, Tinmark, F.2, Carlsson, M.1. 1: Dalarna University (Falun, Sweden), 2: The Swedish School of Sport and Health Sciences (Stockholm, Sweden), 3: The Swedish Golf Federation (Stockholm, Sweden). 

    Introduction

    Previously it was reported that golf-ball temperature has influence on the golf balls’ coefficient of restitution, impact duration, and maximal deformation (Allen et al., 2012). They concluded that their research was the first step in a process for determining the effect of temperature on a golf drive. However, how large influence the golf-ball temperature has on golf drives remains to be investigated. The purpose was to investigate the effect of ball temperature on impact ball speed and carry distance during golf drives in a blind randomized test design. 

    Methods

    The balls were exposed to a temperature-controlled environment (4°C, 18°C, 32°C, and 46°C) for twenty-four hours prior to the test, and each of the four different ball-temperature groups consisted of 30 balls. The 120 drives were performed by an elite male golfer (handicap: 0.0) in an indoor driving range. All drives were measured by a Doppler-radar system to determine club-head speed, launch angle, spin rate, ball speed, and carry distance. Differences between the four ball-temperature groups were investigate using a one-way analysis of variance. 

    Results

    The results indicate that there are ball-speed and carry-distance differences within the four ball-temperature groups (P &lt; 0.001 and P &lt; 0.01, respectively). The post-hoc analyses showed that the ball temperatures 18°C and 32°C had both greater ball speeds and carry distances compared to the balls in the ball-temperature groups 4°C and 46°C (all P &lt; 0.05); the intervals for the between-group differences were 2.0 to 2.4 km/h and 2.9 to 3.9 m for ball speed and carry distance, respectively.

    Conclusion

    The novel results of the current study show that the ball’s temperature has a significant effect on the ball speed after club-head impact and carry distance for drives performed by an elite golfer. The ball temperatures 18°C and 32°C gave significantly increased ball speeds and carry distances compared to the ball-temperature groups 4°C and 46°C. This knowledge could be used to maximise the carry distance and/or to minimise the carry-distance variability related to ball temperature.

    REFERENCES: Allen T, Bowley A, Wood P, Henrikson E, Morales E, James D. (2012) Procedia Eng, 34, 634-639.

  • 94. Carpenter, Mark G
    et al.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Cresswell, Andrew G
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Deceleration affects anticipatory and reactive components of triggered postural responses.2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 167, no 3, p. 433-45Article in journal (Refereed)
    Abstract [en]

    Understanding the physiological and psychological factors that contribute to healthy and pathological balance control in man has been made difficult by the confounding effects of the perturbations used to test balance reactions. The present study examined how postural responses were influenced by the acceleration-deceleration interval of an unexpected horizontal translation. Twelve adult males maintained balance during unexpected forward and backward surface translations with two different acceleration-deceleration intervals and presentation orders (serial or random). "SHORT" perturbations consisted of an initial acceleration (peak acceleration 1.3 m s(-2); duration 300 ms) followed 100 ms later by a deceleration. "LONG" perturbations had the same acceleration as SHORT perturbations, followed by a 2-s interval of constant velocity before deceleration. Surface and intra-muscular electromyography (EMG) from the leg, trunk, and shoulder muscles were recorded along with motion and force plate data. LONG perturbations induced larger trunk displacements compared to SHORT perturbations when presented randomly and larger EMG responses in proximal and distal muscles during later (500-800 ms) response intervals. During SHORT perturbations, activity in some antagonist muscles was found to be associated with deceleration and not the initial acceleration of the support surface. When predictable, SHORT perturbations facilitated the use of anticipatory mechanisms to attenuate early (100-400 ms) EMG response amplitudes, ankle torque change and trunk displacement. In contrast, LONG perturbations, without an early deceleration effect, did not facilitate anticipatory changes when presented in a predictable order. Therefore, perturbations with a short acceleration-deceleration interval can influence triggered postural responses through reactive effects and, when predictable with repeated exposure, through anticipatory mechanisms.

  • 95. Carpenter, Mark G
    et al.
    Tokuno, Craig D
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Cresswell, Andrew G
    Differential control of abdominal muscles during multi-directional support-surface translations in man.2008In: Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale, ISSN 1432-1106, Vol. 188, no 3, p. 445-55Article in journal (Refereed)
    Abstract [en]

    The current study aimed to understand how deep and superficial abdominal muscles are coordinated with respect to activation onset times and amplitudes in response to unpredictable support-surface translations delivered in multiple directions. Electromyographic (EMG) data were recorded intra-muscularly using fine-wire electrodes inserted into the right rectus abdominis (RA), obliquus externus (OE), obliquus internus (OI) and transversus abdominis (TrA) muscles. Twelve young healthy male subjects were instructed to maintain their standing balance during 40 support surface translations (peak acceleration 1.3 m s(-2); total displacement 0.6 m) that were counter-balanced between four different directions (forward, backward, leftward, rightward). Differences between abdominal muscles in EMG onset times were found for specific translation directions. The more superficial RA (backward translations) and OE (forward and leftward translations) muscles had significantly earlier EMG onsets compared to TrA. EMG onset latencies were dependent on translation direction in RA, OE and OI, but independent of direction in TrA. EMG amplitudes in RA and OE were dependent on translation direction within the first 100 ms of activity, whereas responses from the two deeper muscles (TrA and OI) were independent of translation direction during this interval. The current results provide new insights into how abdominal muscles contribute to postural reactions during human stance. Response patterns of deep and superficial abdominal muscles during support surface translations are unlike those previously described during upper-body perturbations or voluntary arm movements, indicating that the neural mechanisms controlling individual abdominal muscles are task-specific to different postural demands.

  • 96. Cedervall, Ylva
    et al.
    Åberg, Anna Cristina
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Physical activity and implications on well-being in mild Alzheimer's disease: A qualitative case study on two men with dementia and their spouses.2010In: Physiotherapy Theory and Practice, ISSN 0959-3985, E-ISSN 1532-5040, Vol. 26, no 4, p. 226-39Article in journal (Refereed)
    Abstract [en]

    To improve the understanding of experiences of people with mild Alzheimer's disease (AD) and their significant others, related to the physical activity of the afflicted persons and its perceived importance. A qualitative case study design was used. The study comprised two men with mild AD and their wives. Data were collected by qualitative interviews and participant observations. Data analysis followed a thematic guideline as described by Braun and Clarke ( 2006 ). Three central themes of experiences related to physical activity in AD were identified: 1) physical activity as health reinforcement; 2) barriers to physical activity; and 3) adaptation strategies. Important motivations for outdoor walks were enjoyable experiences of nature, body movement, and positive attitudes toward physical activity. Several factors were experienced as barriers to physical activity (e.g., tiredness, difficulties in finding one's way, and "peculiar behavior"). Significant others made considerable adjustments in everyday life to enable their partners to retain a physically active lifestyle. The findings indicate that in persons with AD, physical activities such as outdoor walking can play an important part in everyday life by creating meaningful routines and improving experienced well-being and health.

  • 97. Cresswell, A G
    et al.
    Blake, P L
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The effect of an abdominal muscle training program on intra-abdominal pressure.1994In: Scandinavian Journal of Rehabilitation Medicine, ISSN 0036-5505, E-ISSN 1940-2228, Vol. 26, no 2, p. 79-86Article in journal (Refereed)
    Abstract [en]

    The effect of 10 weeks' specific abdominal strength training (resisted trunk rotations) on intra-abdominal pressure was investigated in 10 healthy males. Isometric rotational force, trunk flexor and extensor torque and intra-abdominal pressure were measured as well as intra-abdominal pressure responses to Valsalva manoeuvres, maximal pulsed pressures, drop jumps and trunk perturbations. The rotational strength increased 29.7% after training without significant change in intra-abdominal pressure. The isometric flexor strength did not change, while the extensor strength increased 11.0%. Valsalva and pulsed pressures increased 11.6 and 9.2%, respectively. The rate of intra-abdominal pressure development during pulsed pressures, drop jumps and trunk perturbations increased after training. The level of intra-abdominal pressure during the latter two tasks remained unchanged. It is concluded that an increase in strength of the trunk rotators with training improves the ability to generate higher levels of voluntarily induced intra-abdominal pressure and increases the rate of intra-abdominal pressure development during functional situations.

  • 98. Cresswell, A G
    et al.
    Grundström, H
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Observations on intra-abdominal pressure and patterns of abdominal intra-muscular activity in man.1992In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 144, no 4, p. 409-18Article in journal (Refereed)
    Abstract [en]

    The aim was to investigate possible relationships between activities of the individual muscles of the ventrolateral abdominal wall and the development of pressure within the abdominal cavity. Intra-muscular activity was recorded bilaterally from transversus abdominis, obliquus internus, obliquus externus and rectus abdominis with fine-wire electrodes guided into place using real-time ultrasound. Intra-abdominal pressure was measured intragastrically using a micro tip pressure transducer. Six males were studied during loading and movement tasks with varied levels of intra-abdominal pressure. During both maximal voluntary isometric trunk flexion and extension, transversus abdominis activity and intra-abdominal pressure remained constant, while all other abdominal muscles showed a marked reduction during extension. When maximal isometric trunk flexor or extensor torques were imposed upon a maximal Valsalva manoeuvre, transversus abdominis activity and intra-abdominal pressure remained comparable within and across conditions, whereas obliquus internus, obliquus externus and rectus abdominis activities either markedly increased (flexion) or decreased (extension). Trunk twisting movements showed reciprocal patterns of activity between the left and right sides of transversus abdominis, indicating an ability for torque development. During trunk flexion--extension, transversus abdominis showed less distinguished changes of activity possibly relating to a general stabilizing function. In varied pulsed Valsalva manoeuvres, changes in peak intra-abdominal pressure were correlated with mean amplitude electromyograms of all abdominal muscles, excluding rectus abdominis. It is concluded that the co-ordinative patterns shown between the muscles of the ventrolateral abdominal wall are task specific based upon demands of movement, torque and stabilization. It appears that transversus abdominis is the abdominal muscle whose activity is most consistently related to changes in intra-abdominal pressure.

  • 99. Cresswell, A G
    et al.
    Oddsson, L
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The influence of sudden perturbations on trunk muscle activity and intra-abdominal pressure while standing.1994In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 98, no 2, p. 336-41Article in journal (Refereed)
    Abstract [en]

    Unexpected ventral and dorsal perturbations and expected, self-induced ventral perturbations were delivered to the trunk by suddenly loading a vest strapped to the torso. Six male subjects were measured for intra-abdominal pressure (IAP) and intra-muscular electromyography of the transversus abdominis (TrA), obliquus internus abdominis (OI), obliquus externus abdominis (OE) and rectus abdominis (RA) muscles. Erector spinae (ES) activity was recorded using surface electromyography. Displacements of the trunk and head were registered using a video-based system. Unexpected ventral loading produced activity in TrA, OI, OE and RA, and an IAP increase well in advance of activity from ES. Expected ventral loading produced pre-activation of all muscles and an increased IAP prior to the perturbation. The TrA was always the first muscle active in both the unexpected and self-loading conditions. Of the two ventral loading conditions, forward displacement of the trunk was significantly reduced during the self-loading. Unexpected dorsal loading produced coincident activation of TrA, OI, OE, RA and ES. These results indicate a response of the trunk muscles to sudden expected and unexpected ventral loadings other than the anticipated immediate extensor torque production through ES activation. It is suggested that the increase in IAP is a mechanism designed to improve the stability of the trunk through a stiffening of the whole segment.

  • 100. Cresswell, A G
    et al.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Changes in intra-abdominal pressure, trunk muscle activation and force during isokinetic lifting and lowering.1994In: European Journal of Applied Physiology and Occupational Physiology, ISSN 0301-5548, E-ISSN 1432-1025, Vol. 68, no 4, p. 315-21Article in journal (Refereed)
    Abstract [en]

    Intra-abdominal pressure (IAP), force and electromyographic (EMG) activity from the abdominal (intra-muscular) and trunk extensor (surface) muscles were measured in seven male subjects during maximal and sub-maximal sagittal lifting and lowering with straight arms and legs. An isokinetic dynamometer was used to provide five constant velocities (0.12-0.96 m.s-1) of lifting (pulling against the resistance of the motor) and lowering (resisting the downward pull of the motor). For the maximal efforts, position-specific lowering force was greater than lifting force at each respective velocity. In contrast, corresponding IAPs during lowering were less than those during lifting. Highest mean force occurred during slow lowering (1547 N at 0.24 m.s-1) while highest IAP occurred during the fastest lifts (17.8 kPa at 0.48-0.96 m.s-1). Among the abdominal muscles, the highest level of activity and the best correlation to variations in IAP (r = 0.970 over velocities) was demonstrated by the transversus abdominis muscle. At each velocity the EMG activity of the primary trunk and hip extensors was less during lowering (eccentric muscle action) than lifting (concentric muscle action) despite higher levels of force (r between -0.896 and -0.851). Sub-maximal efforts resulted in IAP increasing linearly with increasing lifting or lowering force (r = 0.918 and 0.882, respectively). However, at any given force IAP was less during lowering than lifting. This difference was negated if force and IAP were expressed relative to their respective lifting and lowering maxima.(ABSTRACT TRUNCATED AT 250 WORDS)

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