Gymnastik- och idrottshögskolan, GIH

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  • 1.
    Fjellstrom, Sanna
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Hansen, Elisabeth
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Hölltä, Jessica
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Zingmark, Magnus
    Health and Social Care Administration, Municipality of Östersund Östersund Sweden;Department of Epidemiology and Global Health, Faculty of Medicine Umeå University Umeå Sweden;Department of Health Sciences, Faculty of Medicine Lund University Lund Sweden.
    Nordström, A.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Web‐based training intervention to increase physical activity level and improve health for adults with intellectual disability2022In: Journal of Intellectual Disability Research, ISSN 0964-2633, E-ISSN 1365-2788, Vol. 66, no 12, p. 967-977Article in journal (Refereed)
    Abstract [en]

    Background: Individuals with intellectual disability (ID) are less physically active, have a higher body mass index (BMI) and are at greater risk for cardiovascular diseases (CVDs) than people without ID. The purpose of the study was to explore the effectiveness of a web-based training programme, consisting of 150 min of activity per week, on the health of people with ID.

    Method: Participants with ID living in supported accommodation (n = 28, 48% female, age = 36.4 ± 9.56 years) participated in a web-based training programme, consisting of a combination of exercises (endurance, strength balance and flexibility) of moderate intensity, 50 min, three times per week for 12 weeks. The body composition and waist circumference (WC) were measured, and questionnaires were used to assess enjoyment, quality of life (QoL) and physical activity (PA) level. Descriptive statistics and pairwise comparison pre and post intervention were carried out.

    Results: A total of 22 out of 28 participants completed the 12-week training intervention with 83% mean attendance of training sessions. The intensity of the PA level increased and a decrease in fat mass of 1.9 ± 2.4 kg, P < 0.001 and WC of 3 ± 5 cm, P = 0.009 were observed. Enjoyment of training sessions was 3.9 out of 5, and no differences in QoL were found.

    Conclusion: A web-based training programme is an effective tool for improving health parameters of people with ID and offers a new way for caregivers to enhance the PA for the target group.

  • 2.
    Fjellström, Sanna
    et al.
    Department of Health Sciences, Swedish Winter Sport Research Centre Mid Sweden University Sundsvall Sweden.
    Hölttä, Jessica
    Department of Health Sciences, Swedish Winter Sport Research Centre Mid Sweden University Sundsvall Sweden.
    Nordström, Anna
    Department of Health Sciences, Swedish Winter Sport Research Centre Mid Sweden University Sundsvall Sweden;School of Sports Science UiT The Arctic University of Norway Tromsø Norway;Department of Medical Sciences Uppsala University Uppsala Sweden.
    Flygare Wallén, Eva
    Karolinska Institutet (KI), Department of Neurobiology, Care Sciences and Society (NVS) Division of Occupational Therapy Research group Health in Everyday Life among people with neurological Disorders (HELD) Stockholm Sweden;Health and Social Care Administration Municipality of Östersund Östersund Sweden.
    Lund Ohlsson, Marie
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Health Sciences, Swedish Winter Sport Research Centre Mid Sweden University Sundsvall Sweden.
    Hansen, Elisabeth
    Department of Health Sciences, Swedish Winter Sport Research Centre Mid Sweden University Sundsvall Sweden;The Faculty of Education and Arts Nord University Bodø Norway.
    Increasing physical activity through an adapted web‐based exercise program for people with intellectual disabilities: Support staff are crucial for feasibility2024In: JARID: Journal of applied research in intellectual disabilities, ISSN 1360-2322, E-ISSN 1468-3148, Vol. 37, no 2, article id e13191Article in journal (Refereed)
    Abstract [en]

    Background

    People with intellectual disabilities are less physically active and suffer from ill-health more than the general population. Support staff play an important role in the person's life. This study aimed to explore the support staff's experiences regarding the feasibility of adapted web-based exercise for people with intellectual disabilities.

    Method

    Participants with intellectual disabilities living in community-based settings were recruited for a web-based exercise study. Eight semi-structured interviews were carried out with their support staff before and after the intervention period.

    Results

    The main theme, ‘Support staff are crucial for feasibility’ encompasses the importance of communication, structure, and motivation in improving physical activity for people with intellectual disabilities.

    Conclusion

    The experiences of support staff, indicate that a web-based exercise program is feasible for the target group, and one way to overcome challenges for PA, where the role of the staff is crucial.

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  • 3.
    Hansen, Elisabeth
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Nordén, Helena
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Adolescents with intellectual disability (ID) and their perceptions of activity and sports2019In: LICE-2019, 2019Conference paper (Refereed)
  • 4.
    Hansen, Elisabeth
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Nordén, Helena
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Adolescents with intellectual disability (ID) and their perceptions of activity and sports2019In: 12th European Public Health Congress, Marseille, France, 20-23 november 2019: Building bridges for solidarity and public health, 2019Conference paper (Refereed)
  • 5.
    Hansen, Elisabeth
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Nordén, Helena
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Adolescents with intellectual disability (ID) and their perceptions of, and motivation for, physical activity and organised sports2023In: Sport, Education and Society, ISSN 1357-3322, E-ISSN 1470-1243, Vol. 28, no 1, p. 59-72Article in journal (Refereed)
    Abstract [en]

    Individuals with intellectual disability (ID) are less physically active than individuals without ID, and rarely reach the recommended daily level of physical activity (PA). It is understood that both social interaction and the ability to perform physical work affect participation in daily activity as well as PA. Individuals with ID generally have a higher risk of hypertension and obesity-related cardiovascular diseases than individuals without ID. Professional service providers, teachers and parents are often those being asked about potential challenges related to PA, as it is more seldom that this knowledge comes from the target group (ID) themselves. This identifies a lack of knowledge about PA and sports for individuals with ID. The aim of this study was to identify perceptions of, and motivation for, PA and sports among adolescents with ID. Twelve Swedish male and female adolescents with ID participated in the study, which comprised one semi-structured interview. The interviews identified three main categories: Activity, Surroundings and Body- and health awareness. Adolescents with ID seemed intrinsic motivated to participate in PA, organised sports and activities in general. Support from significant others, teachers, family and friends and support as well as the feeling of joy are connected to normative beliefs which all seem crucial. The participants were aware of their limitations, but sometimes feel bullied and afraid of being excluded, which relates to their normative beliefs. Participation in PA and organised sports may be positively associated with health, but limitations such as lack of awareness and support from society challenge the perception of ‘fitting in’. This research has raised the voice of adolescents with ID and identified the need for increased knowledge of their perceptions for a more inclusive world. School PE is an arena where adolescents can still be reached regarding PA and thereby should be prioritised. 

  • 6.
    Hofmann, K. B.
    et al.
    Otto Bock Healthcare Products GmbH, Vienna, Austria.
    Ohlsson, M. L.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Höök, M.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Danvind, J.
    Mittuniversitetet, Avdelningen för kvalitetsteknik, maskinteknik och matematik.
    Kersting, U. G.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    The influence of sitting posture on mechanics and metabolic energy requirements during sit-skiing: a case report2016In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 19, no 3, p. 213-218Article in journal (Refereed)
    Abstract [en]

    Several different sitting postures are used in Paralympic cross-country sit-skiing. The aim of this study was to evaluate the impact of sitting posture on physiological and mechanical variables during steady-state double-poling sit-skiing, as well as to determine how seat design can be improved for athletes without sufficient trunk control. Employing a novel, custom-designed seat, three trunk positions were tested while performing double-poling with submaximal oxygen consumption on an ergometer. Cycle kinematics, pole forces, and oxygen consumption were monitored. The athlete performed best, with longer cycle length and less pronounced metabolic responses, when kneeling with the trunk resting on a frontal support. For this case, a forward leaning trunk with knees below the hip joint was interpreted as most optimal, as it showed lower oxygen consumption and related parameters of performance during cross-country sit-skiing. Further investigations should examine whether such improvement is dependent on the level of the athlete’s handicap, as well as whether it is also seen on snow.

  • 7.
    Holmberg, Joakim
    et al.
    Linköpings Universitet.
    Lund, Marie
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    A Musculoskeletal Full‐body Simulation of Cross‐Country Skiing2008In: Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, ISSN 1754-3371, Vol. 222, no P1, p. 11-22Article in journal (Refereed)
    Abstract [en]

    This paper presents a measurement-driven, musculoskeletal, full-body simulation model for biomechanical analysis of the double-poling (DP) technique in cross-country skiing. DP is a fast and powerful full-body movement; therefore, it is interesting to examine whether inverse dynamics using static optimization is working for a musculoskeletal full-body model with high accelerations, a large range of motion, and realistic loads. An experiment was carried out to measure motion and pole force of a skier on a double-poling ergometer. Using the measurement data, a simulation model was implemented in the AnyBody Modeling System (AnyBody Technology A/S, Denmark). Experimental results of motion and pole force from the DP ergometer, and also simulation results of relative muscle force profiles, are presented. These results agree with results found in literature when the kinematics and external kinetics are similar. Consequently, it should be possible to use computer simulations of this type for cross-country skiing simulations. With a simulation model, it is possible to perform optimization studies and to ask and answer ‘what if’ questions. Solutions to such problems are not easy to obtain by traditional testing alone.

  • 8.
    Holmberg, Joakim
    et al.
    Linköpings Universitet.
    Lund, Marie
    Mittuniversitetet, Institutionen för teknik, fysik och matematik (-2008).
    Using Double‐Poling Simulations to Study the Load Distribution between Teres Major and Latissimus Dorsi2007In: Science and Nordic Skiing, Oxford: Meyer & Meyer Sport , 2007, p. 81-89Conference paper (Refereed)
  • 9.
    Holmberg, Joakim
    et al.
    Linköpings universitet.
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Biomekaniska simuleringar adderar insikt om längdskidåkning2010In: Svensk Idrottsforskning: Organ för Centrum för Idrottsforskning, ISSN 1103-4629, Vol. 19, no 1, p. 38-40Article in journal (Other (popular science, discussion, etc.))
  • 10.
    Holmberg, Joakim
    et al.
    Univ, Div Mech, Dept Management & Engn, Inst Technol, SE-58183 Linkoping, Sweden.
    Lund Ohlsson, Marie
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Supej, Matej
    Univ Ljubljana, Fac Sport, Ljubljana, Slovenia.
    Holmberg, Hans-Christer
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Skiing efficiency versus performance in double-poling ergometry2013In: Computer Methods in Biomechanics and Biomedical Engineering, ISSN 1025-5842, E-ISSN 1476-8259, Vol. 16, no 9, p. 987-992Article in journal (Refereed)
    Abstract [en]

    This study is on how leg utilisation may affect skiing efficiency andperformance in double-poling ergometry. Three experiments wereconducted, each with a different style of the double-poling technique:traditional with small knee range-of-motion and fixed heels (TRAD);modern with large knee range-of-motion and fixed heels (MOD1) and modernwith large knee range-of-motion and free heels (MOD2). For each style,motion data were extracted with automatic marker recognition ofreflective markers and applied to a 3D full-body musculoskeletalsimulation model. Skiing efficiency (skiing work divided by metabolicmuscle work) and performance (forward impulse) were computed from thesimulation output. Skiing efficiency was 4.5%, 4.1% and 4.1% for TRAD,MOD1 and MOD2, respectively. Performance was 111, 143 and 149Ns forTRAD, MOD1 and MOD2, respectively. Thus, higher lower body utilisationincreased the performance but decreased the skiing efficiency. Theseresults demonstrate the potential of musculoskeletal simulations forskiing efficiency estimations.

  • 11.
    Holmberg, L. Joakim
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap (-2013).
    Ohlsson, Marie
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Danvind, Jonas
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Musculoskeletal simulations: a complementary tool for classification of athletes with physical impairments2012In: Prosthetics and Orthotics International, ISSN 0309-3646, E-ISSN 1746-1553, Vol. 36, no 3, p. 396-397Article in journal (Refereed)
  • 12.
    Jonsson Kårström, Malin
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Stöggl, Thomas
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    McGawley, Kerry
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Laaksonen, Marko S.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Kinematical effects of rifle carriage on roller skiing in well-trained female and male biathletes2023In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 33, no 4, p. 444-454Article in journal (Refereed)
    Abstract [en]

    Purpose: This study aimed to investigate how rifle carriage and skiing speed during biathlon roller skiing affect range of motion (ROM) in joint angles and equipment (skis and poles), the vertical distance between shoulders and treadmill (vertdist), as well as possible sex differences associated with rifle carriage. Methods: Fourteen biathletes (6 women, 8 men) roller-skied on a treadmill at submaximal and simulated race speeds, with (WR) and without (NR) a rifle, using gears 3 and 2. Kinematical data for the whole body, poles, roller-skis, rifle, and treadmill were monitored using a 3D motion capture system. Movements determined as flexion/extension (x), abduction/adduction (y), and/or internal/external rotation (z) were analyzed for the hip, shoulder, thorax, knee, ankle, elbow, poles, and roller skis. ROM (the difference between maximal and minimal angles) in joints and equipment, and vertdist were analyzed over six skiing cycles during each condition (WR and NR) and speed. Results: The maximal vertdist was lower for WR compared with NR (gear 3: 1.53 ± 0.06 vs 1.54 ± 0.06 m; gear 2: 1.49 ± 0.06 vs 1.51 ± 0.06 m; both p &lt; 0.001). ROM in the upper body was altered when roller skiing WR (movements decreased in thorax and shoulder (x) and increased in elbow (only gear 3) (x), thorax (only gear 2), and shoulder (y) and (z); all p &lt; 0.05) and increased with speed, without differences between sexes (p &gt; 0.05). Conclusion: Since rifle carriage and speed appear to affect the kinematics of roller skiing, coaches, and biathletes are advised to perform skiing technique training under competition-like conditions (i.e., at race speeds while carrying the rifle). 

  • 13.
    Jonsson Kårström, Malin
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Stöggl, Thomas
    Department of Sport and Exercise Science, University of Salzburg.
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    McGawley, Kerry
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Laaksonen, Marko S.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Kinematical Effects of Rifle Carriage on Roller-Skiing in Well-Trained Female and Male Biathletes2022Conference paper (Other academic)
    Abstract [en]

    Purpose 

    This study aimed to investigate how rifle carriage and skiing speed during biathlon roller-skiing affect range of motion (ROM) in joint angles and equipment (skis and poles), the vertical distance between shoulders and treadmill (vertdist), as well as possible sex differences associated with rifle carriage. 

    Methods 

    Fourteen biathletes (6 women, 8 men) roller-skied on a treadmill at submaximal and simulated race speeds, with (WR) and without (NR) a rifle, using gears 3 and 2. Kinematical data for the whole body, poles, roller-skis, rifle and treadmill were monitored using a 3D motion capture system. Movements determined as flexion/extension (x), abduction/adduction (y) and/or internal/external rotation (z) were analyzed for the hip, shoulder, thorax, knee, ankle, elbow, poles and roller-skis. ROM (the difference between maximal and minimal angles) in joints and equipment, and vertdist were analyzed over six skiing cycles during each condition (WR and NR) and speed. 

    Results 

    The maximal vertdist was lower for WR compared to NR (gear 3: 1.53±0.06 vs 1.54±0.06 m; gear 2: 1.49±0.06 vs 1.51±0.06 m; both p<0.001). ROM in the upper body was altered when roller-skiing WR (movements decreased in thorax and shoulder (x) and increased in elbow (only gear 3) (x), thorax (only gear 2) and shoulder (y) and (z); all p><0.05) and increased with speed, without differences between sexes (p>0.05). 

    Conclusion 

    Since rifle carriage and speed appear to affect the kinematics of rollerskiing, coaches and biathletes are advised to perform skiing technique training under competition-like conditions (i.e., at race speeds while carrying the rifle).

  • 14.
    Lund, Marie
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Holmberg, Joakim
    Linköpings Universitet.
    Which are the Antagonists to the Pectoralis MajorMuscle in 4th Gear, Free‐style Technique, Cross‐Country Skiing?2008In: Science and Nordic Skiing, Oxford: Meyer & Meyer Sport , 2008, p. 110-118Conference paper (Refereed)
  • 15.
    Lund, Marie
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Ståhl, Fredrik
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Gulliksson, Mårten
    Mittuniversitetet, Institutionen för naturvetenskap, teknik och matematik (-2012).
    Regularity Aspects in Inverse Musculoskeletal Biomechanics2008In: NUMERICAL ANALYSIS AND APPLIED MATHEMATICS / [ed] Simos, TE; Psihoyios, G; Tsitouras, C, American Institute of Physics (AIP) , 2008, p. 368-371Conference paper (Refereed)
    Abstract [en]

    Inverse simulations of musculoskeletal models computes the internal forces such as muscle and joint reaction forces, which are hard to measure, using the more easily measured motion and external forces as input data. Because of the difficulties of measuring muscle forces and joint reactions, simulations are hard to validate. One way of reducing errors for the simulations is to ensure that the mathematical problem is well-posed. This paper presents a study of regularity aspects for an inverse simulation method, often called forward dynamics or dynamical optimization, that takes into account both measurement errors and muscle dynamics. Regularity is examined for a test problem around the optimum using the approximated quadratic problem. The results shows improved rank by including a regularization term in the objective that handles the mechanical over-determinancy. Using the 3-element Hill muscle model the chosen regularization term is the norm of the activation. To make the problem full-rank only the excitation bounds should be included in the constraints. However, this results in small negative values of the activation which indicates that muscles are pushing and not pulling, which is unrealistic but the error maybe small enough to be accepted for specific applications. These results are a start to ensure better results of inverse musculoskeletal simulations from a numerical point of view.

  • 16.
    Lund Ohlsson, Marie
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Double Poling Incross-Country Skiing: Biomechanical and Physiological Analysis of Sitting and Standing Positions2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Double poling (DP) is a sub-technique in cross-country skiing that has increased in interest over the last decades, e.g. athletes in cross-country skiing have increased their utilisation of double poling during competitions. In cross-country sit-skiing athletes with impairments in legs and/or trunk sit in a sledge and utilise DP to propel themselves. Technique (i.e. movement pattern) is one key factor determining performance but also a factor that may affect the risk of overuse injuries in sports.

    Therefore, the overall aim of the thesis was to improve the understanding of the human movement technique in cross-country skiing DP, in both standing (paper I-II) and sitting positions (paper III-IV, Thesis A-B) using biomechanical and physiological measurements and inverse dynamics simulations. All studies were carried out on a double poling ergometer in laboratory. Three experimental studies were performed with able-bodied participants (papers I-II, IV-VI), one study with one participant with growth defect in the legs (paper III), and one study (Thesis B) with one participant with complete spinal cord injury at thoracic vertebra 4.

    In paper I the first full-body simulation of DP was performed and results were comparable to results found in literature when the kinematics and external kinetics were similar. Paper II showed how increased leg utilisation increased performance (forward impulse) but reduced skiing efficiency (output work divided by metabolic muscle work). These results indicate that both high performance (power output) and efficiency may not be achieved in the same technique.

    In sitting DP many different sitting positions are utilised. Athletes with full muscle control in hip and trunk mainly sit with their knees lower than their hips (KLnoS). Athletes with paralysis in lower trunk and legs need trunk stability from the sit-ski. Most often, this is achieved by adopting a knees higher than hips (KH) position together with a support for the lower back. However, this position might induce large flexion in the spine, which is hypothesised to affect injury risk in the shoulders and lower back. This thesis has enabled the knees low sitting position for athletes with paralysis in the lower trunk and legs by supporting the anterior trunk with the sledge (KL).

     

    In sitting DP in athletes with full hip and trunk muscle control, high performance was achieved through proximal-distal sequencing from the hips through the trunk to the arms, and large muscle work in spine and legs (IV, V, Thesis A). In order of performance, KLnoS utilised muscles in the hips-spine-arms, compared with utilisation of spine-arms in KH, and mainly arms in KL. Higher amount of activated muscle mass resulted in lower relative anaerobic metabolism during submaximal exercise (IV).

    The lower back joint reactions were higher for the sitting position with larger spinal flexion, KH compared to KL (VI). These results suggest that there is an increased risk of injury in the lower back for the sitting position KH. Athletes with paraplegia generally have a high risk of injuries in the shoulders. The results of this thesis showed higher shoulder joint reactions in the sitting position with larger shoulder-arm muscle work, in KL compared to KH.

    For the case study with one participant with thoracic spinal cord injury (Thesis B) highest performance was achieved in the KH sitting position where spinal flexion occurred at the beginning of the poling phase. When comparing the fixed trunk positions KL and KHS, higher performance was achieved in KHS. It was speculated that the difference between KL and KHS was due to the impairment of the vasoconstriction in paralysed muscles. The effect of gravity on venous pooling is probably larger when the legs are lower down as in KL. This effect was not present for individuals without paralysis (III), where KL was more economical than KHS.

    Parasport classification needs evidence of how impairment affects sporting performance (Tweedy et al., 2014, Tweedy and Vanlandewijck, 2011). Classification might benefit from simulations as performed in this thesis. The musculoskeletal simulations of seated DP in paper V and the KLnoS position presented in the thesis have showed the relative contribution of different muscle groups on performance. These results are novel and might contribute to improvement of the classification system.

  • 17.
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för naturvetenskap, teknik och matematik (-2012).
    New methods for movement technique development in cross-country skiing using mathematical models and simulation2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This Licentiate Thesis is devoted to the presentation and discussion of some new contributions in applied mathematics directed towards scientific computing in sports engineering. It considers inverse problems of biomechanical simulations with rigid body musculoskeletal systems especially in cross-country skiing. This is a contrast to the main research on cross-country skiing biomechanics, which is based mainly on experimental testing alone. The thesis consists of an introduction and five papers. The introduction motivates the context of the papers and puts them into a more general framework. Two papers (D and E) consider studies of real questions in cross-country skiing, which are modelled and simulated. The results give some interesting indications, concerning these challenging questions, which can be used as a basis for further research. However, the measurements are not accurate enough to give the final answers. Paper C is a simulation study which is more extensive than paper D and E, and is compared to electromyography measurements in the literature. Validation in biomechanical simulations is difficult and reducing mathematical errors is one way of reaching closer to more realistic results. Paper A examines well-posedness for forward dynamics with full muscle dynamics. Moreover, paper B is a technical report which describes the problem formulation and mathematical models and simulation from paper A in more detail. Our new modelling together with the simulations enable new possibilities. This is similar to simulations of applications in other engineering fields, and need in the same way be handled with care in order to achieve reliable results. The results in this thesis indicate that it can be very useful to use mathematical modelling and numerical simulations when describing cross-country skiing biomechanics. Hence, this thesis contributes to the possibility of beginning to use and develop such modelling and simulation techniques also in this context.

  • 18.
    Lund Ohlsson, Marie
    et al.
    Linköpings universitet.
    Danvind, Jonas
    Mittuniversitetet, Avdelningen för kvalitetsteknik, maskinteknik och matematik.
    Holmberg, Joakim
    Linköpings universitet.
    Can Simulations Assist in Classification Development?2013In: Equipment and Technology in Paralympic Sports, International Paralympic Committee , 2013Conference paper (Refereed)
  • 19.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Danvind, Jonas
    Mittuniversitetet, Institutionen för kvalitets- och maskinteknik.
    Holmberg, L Joakim
    Linköping University.
    Estimation of muscle work in cross-country sit-skiing2019Conference paper (Refereed)
    Abstract [en]

    Introduction: In Nordic skiing all sitting athletes compete in the same event competition. The sitting positions differ between athletes. Most of the athletes sit knee-seated, or with their thighs tilted downward (KL) and free to move their trunk. Some athletes do not have the possibility to sit in that position and therefore adjust their sitting position. For example, athletes with reduced muscle control in hips and lower trunk sit with their knees higher than their hips (KH) to increase stability.

    Purpose: The purpose of this study was to examine how sitting position KL and KH affects the muscular power.

    Methods: One female able-bodied athlete performed one test session in each sitting position (KL and KH) comprising five times 3 minutes sub-maximal exercise and a maximal time-trial in a double-poling ergometer (ThoraxTrainer A/S, Denmark). During the tests 3D kinematics (Qualisys AB, Sweden), pole forces and power output were measured. From the measured data, participant and test specific musculo-skeletal inverse-dynamics simulation models were created using the AnyBody Modelling system (AMS 6.0, Anybody Technology A/S, Denmark). From the simulations of submaximal exercise power output 37 W, 52 W and maximal time-trial the muscular metabolic power (mMP) was computed according to Holmberg (2013).

    Results: The power output in maximal exercise was higher in KL (90.1 W) compared to KH (74.7 W). During both submaximal and maximal exercise, the total muscular metabolic power was larger in KL compared to KH (KL mean 861 W and KH mean 682 W). The muscular metabolic power also showed larger relative involvement of legs in KL (KL mean 18 % and KH mean 4 %) and larger relative involvement of arms and trunk in KH.

    Conclusion: That sitting position KL compared to KH is related to higher performance for athletes without impairment in hips and trunk is known before (Gastaldi, 2012). However, the results from this study explains why performance is higher in KL, i.e. that larger muscular metabolic power are produced in the legs. This study also shows the size of the involvement of legs, which could be interesting for development of classification rules.

  • 20.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Danvind, Jonas
    Mittuniversitetet, Institutionen för kvalitets- och maskinteknik.
    Holmberg, L. Joakim
    Solid Mechanics, Department of Management and Engineering, Linköping University, Linköping, Sweden.
    Estimation of muscular metabolic power in two different cross-country sit-skiing sledges using inverse-dynamics simulation2022In: Journal of Rehabilitation and Assistive Technologies Engineering, ISSN 2055-6683, Vol. 9Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to estimate and compare the muscular metabolic power produced in the human body using musculoskeletal inverse-dynamics during cross-country sit-skiing. Two sitting positions were adapted for athletes with reduced trunk and hip muscle control, knee low with frontal trunk support (KL-fix), and knee high (KH). Five female national class able-bodied cross-country skiers performed submaximal and maximal exercise in both sitting positions, while recording 3-D kinematics, pole forces, electromyography and respiratory variables. Simulations were performed from these experimental results and muscular metabolic power was computed. The main part of the muscle metabolic power was produced in the upper limbs for both sitting positions, but KH produced more muscle metabolic power in lower limbs and trunk during maximal intensity. KH was also more efficient, utilizing less muscular metabolic power during submaximal intensities, relatively less power in the upper limbs and more power in the trunk, hip and lower limb muscles. This implies that sitting position KH is preferable for high power output when using able-bodied simulation models. This study showed the potential of using musculoskeletal simulations to improve the understanding of how different equipment design and muscles contribute to performance.

  • 21.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Danvind, Jonas
    Mittuniversitetet, Avdelningen för kvalitetsteknik, maskinteknik och matematik.
    Holmberg, L. Joakim
    Linköping University.
    LUMBAR SPINE REACTION FORCES IN SEATED PARA-SPORT: CROSS-COUNTRY SIT-SKIING2017In: Brisbane 2017: Abstract book, 2017Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION

    For wheel-chair users shoulder injuries [1] and lower back injuries [2] are common. Lower back kyphosis of the spine, increases the anterior shear force in the lower back [3] and increases the risk of shoulder injuries [4].

     

    Cross-country sit-skiing (CCSS) is an endurance sport where the athlete is seated in a sledge mounted on a pair of skis and propel themselves by poling with a pair of sticks. This sport creates more equal loading on the muscles around the shoulder than wheel-chair rolling [5] which is positive in an injury perspective for the gleno-humeral joint [1].

     

    Athletes in CCSS with reduced trunk muscle control often sits in a sledge with their knees higher than their hips (KH) and a backrest. This position is hypothesized to be associated with spinal kyphosis and hence an increased risk of injuries. Therefore we have created a new sitting position with knees lower than hips (KL) with the trunk restrained on a frontal support.

     

    The aim of this study was to compute the L4/L5 joint reactions and compare the results between the positions KH and KL.

    METHODS

    Five female abled-bodied cross-country skiing athletes (62.6 ± 8.1kg, 1.67 ± 0.05m)  performed one exercise test session in each sitting position; The sessions included a sub-maximal incremental test, including 4-6 exercise levels of 3 min (exercise intensity nr 4, 37W, reflected race-pace) and a maximal time-trial (MAX) of 3 min on a commercial skiing ergometer (ThoraxTrainer A/S, Denmark).

     

    Full-body kinematics (Qualisys AB, Sweden) and pole forces (Biovision, Germany) were measured in 200 Hz. These data served as input to inverse dynamic simulations in The AnyBody Modelling system (AMS 6.0, Anybody Technology A/S, Denmark). For each participant and sitting position, simulations were made for exercise intensity 37W and MAX over four poling cycles using a 5th order polynomial muscle recruitment criteria. Compression forces and anterior shear forces between L4 and L5 were computed and normalized to each participant’s standing joint reactions. Data were compared pair-wise between the two sitting positions.

     

    Statistical significance (p ≤ 0.05) were marked with asterisk (*). Tendency of difference (0.05 ≤ p < 0.10) were marked (ǂ).

     

    RESULTS AND DISCUSSION

    Performance was higher in position KH (KL: 0.77±0.08 W/kg, KH: 1.00±0.14 W/kg, p < 0.01). No difference were observed in cycle length or cycle time. Kinematics results showed that KL had less spine flexion and range of motion in flexion. KH showed higher mean pole force in 37W and tendency of higher peak pole force in MAX.

     

    In standing, L4/L5 compression and anterior shear forces were 354 ± 45N and 32 ± 11N respectively. The normalized L4/L5 reaction forces (fig. 1) were larger in KH, especially during MAX intensity due to higher power. For equal power output, 37W, the mean anterior shear force was larger in KH and the mean compression force showed tendency of larger in KH (p=0.077).

     

    Figure 1: Normalized joint reaction forces, compression and anterior shear forces, between vertebrae L4/L5 for the two sitting positions KH and KL with trunk restraint. Min – minimal force, Maximal force and Mean – mean force over the four poling cycles.

     

    CONCLUSIONS

    Based on inverse-dynamics musculo-skeletal simulations of 5 abled-bodied athletes, the sitting position KL with frontal restraint reduced the compression and shear force between the L4/L5 vertebrae but impeded performance. This study shows the difficulty of comparing performance and safety in the same piece of equipment.

     

    ACKNOWLEDGEMENTS

    The authors acknowledge the Rolf & Gunilla Enström foundation and the Promobilia foundation, Sweden, for financial support, and the Ableway AB (Sweden) for construction of the sledges.

     

    REFERENCES

    1. Burnham RS, et al., Am J Sports Med, 21: 238-242, 1993.
    2. Thyberg M, et al., Disabil rehabil. 23:677-682, 2001.
    3. McGill SM, et al., Clin Biomech, 15: 777-780, 2000.
    4. Samuelsson KA, et al., J Rehabil Res Dev, 41: 65-74, 2004.
    5. Bjerkefors A, et al., Int J Sports Med, 34: 176-182, 2013.
  • 22.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Danvind, Jonas
    Mittuniversitetet, Avdelningen för kvalitets- och maskinteknik.
    Holmberg, L. Joakim
    Linköpings Universitet.
    Shoulder and Lower Back Joint Reaction Forces in Seated Double Poling2018In: Journal of Applied Biomechanics, ISSN 1065-8483, E-ISSN 1543-2688, Vol. 34, no 5, p. 369-376Article in journal (Refereed)
    Abstract [en]

    Overuse injuries in the shoulders and lower back are hypothesized to be common in cross-country sit-skiing. Athletes with reduced trunk muscle control mainly sit with the knees higher than the hips (KH). To reduce spinal flexion, a position with the knees below the hips (KL) was enabled for these athletes using a frontal trunk support. The aim of the study was to compare the shoulder joint (glenohumeral joint) and L4-L5 joint reactions of the KL and KH sitting positions. Five able-bodied female athletes performed submaximal and maximal exercise tests in the sitting positions KL and KH on a ski ergometer. Measured pole forces and 3-dimensional kinematics served as input for inverse-dynamics simulations to compute the muscle forces and joint reactions in the shoulder and L4-L5 joint. This was the first musculoskeletal simulation study of seated double poling. The results showed that the KH position was favorable for higher performance and decreased values of the shoulder joint reactions for female able-bodied athletes with full trunk control. The KL position was favorable for lower L4-L5 joint reactions and might therefore reduce the risk of lower back injuries. These results indicate that it is hard to optimize both performance and safety in the same sit-ski.

  • 23.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Gulliksson, Mårten
    Mittuniversitetet, Institutionen för naturvetenskap, teknik och matematik (-2012).
    Least Squares Approach to Inverse Problems in Musculoskeletal Biomechanics2009Report (Other academic)
    Abstract [en]

    Inverse simulations of musculoskeletal models computes the internal forces such as muscle and joint reaction forces, which are hard to measure, using the more easily measured motion and external forces as input data. Because of the difficulties of measuring muscle forces and joint reactions, simulations are hard to validate. One way of reducing errors for the simulations is to ensure that the mathematical problem is well-posed. This paper presents a study of regularity aspects for an inverse simulation method, often called forward dynamics or dynamical optimization, that takes into account both measurement errors and muscle dynamics. The simulation method is explained in detail. Regularity is examined for a test problem around the optimum using the approximated quadratic problem. The results shows improved rank by including a regularization term in the objective that handles the mechanical over-determinancy. Using the 3-element Hill muscle model the chosen regularization term is the norm of the activation. To make the problem full-rank only the excitation bounds should be included in the constraints. However, this results in small negative values of the activation which indicates that muscles are pushing and not pulling. Despite this unrealistic behavior the error maybe small enough to be accepted for specific applications. These results is a starting point start for achieving better results of inverse musculoskeletal simulations from a numerical point of view.

  • 24.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Höök, M.
    Laaksonen, Marko S.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    On the effect of sitting position, in simulated cross-country sit-skiing2016Conference paper (Refereed)
    Abstract [en]

    Introduction

    In Cross-country sit-skiing (CCSS), athletes with severe reduced trunk control are mainly seated with the knees higher than the hip (KH; arm and trunk powered). However this posture is hypothesized to have high risk for lower back and shoulder injuries. Therefore, a new seat was created where the knees were lower than hip and the trunk frontal supported (KL), to improve spinal curvature. Thus, the aim of this study was to examine performance between these two different sitting positions.

    Methods

    10 female abled-bodied elite cross-country skiers (age 25.5 ± 3.8 years (mean ± standard deviation), height 1.65 ± 0.05 m and weight 61.1 ± 6.8 kg) were tested on a skiing ergometer (ThoraxTrainer, ThoraxTrainer A/S, Kokkedal, Denmark) in a 30 s all-out test (WIN), a submaximal incremental test with 3-6 levels of 3 min (SUB), and a maximal 3 min time-trial test (MAX). The SUB and MAX tests were monitored breath-by-breath with a stationary metabolimeter (Quark CPET, COSMED, Italy). Aerobic metabolism and gross efficiency were computed from oxygen uptake, and anaerobic metabolism were estimated from net blood lactate concentrations. Muscle oxygenation saturation (SmO2) in right vastus lateralis (VL) was monitored with NIRS methodology (Moxy Monitor, Fortiori Design LLC, Minnesota, USA).

    Results

    Higher performance (W·kg-1) was observed for KH both in WIN (KL: 1.13 ± 0.33, KH: 1.40 ± 0.30) and MAX (KL: 0.67 ± 0.14, KH: 0.88 ± 0.19) compared to KL (p < 0.01). No differences were observed in breathing rate, cycle rate, oxygen consumption or aerobic metabolic rate neither in SUB nor MAX. The KH position showed higher gross efficiency and lower anaerobic metabolic rate and minute ventilation. SmO2 was higher for KH compared to baseline bench (12.2 ± 7.2%) whereas no difference was observed between baseline and KL position (3.2 ± 5.5%). During SUB levels 1-4, higher SmO2 was observed for KH compared to KL when normalizing data with baseline bench (p < 0.05).

    Discussion

    This study showed that abled bodied athletes perform better and have higher efficiency in KH compared to KL. The position using larger part of the body (joint range of motion and amount of active muscle mass) have higher gross efficiency, lower lactate concentration and lower ventilation, also shown by Lajunen (2014). It was also concluded that SmO2 was higher in KH compared to KL, and thus there might be a smaller risk for injuries in the legs connected to circulation. This study of abled-bodied athletes have the potential to serve as a control for future studies of para-athletes. 

    References

    Lajunen K (2014). Effect of sitting posture on sit-skiing economy. Bachelor’s thesis, University of Jyväskylä.

  • 25.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Laaksonen, Marko
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Sitting position affects performance in cross-country sit-skiing2017In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 117, no 6, p. 1095-1106Article in journal (Refereed)
    Abstract [en]

    Purpose: In cross-country sit-skiing (XCSS), athletes with reduced trunk control predominantly sit with the knees higher than the hips (KH); a position often associated with large spinal flexion. Therefore, to improve spinal curvature a new sledge with frontal trunk support, where knees are lower than hips (KL) was created. It was hypothesized that the KL position would improve respiratory function and enhance performance in seated double-poling compared to KH.

    Methods: Ten female able-bodied cross-country skiers (age 25.5 ± 3.8 years, height 1.65 ± 0.05 m, mass 61.1 ± 6.8 kg) completed a 30 s all-out test (WIN), a submaximal incremental test including 3–7 3 min loads (SUB) and a maximal 3 min time trial (MAX) in both KL and KH positions. During SUB and MAX external power, pole forces, surface electromyography, and kinematics were measured. Metabolic rates were calculated from oxygen consumption and blood lactate concentrations.

    Results: KL reduced spinal flexion and range of motion at the hip joint and indicated more muscle activation in the triceps. Performance (W kg−1) was impeded in both WIN (KH 1.40 ± 0.30 vs. KL 1.13 ± 0.33, p < 0.01) and MAX (KH 0.88 ± 0.19 vs. KL 0.67 ± 0.14, p < 0.01). KH resulted in higher gross efficiency (GE) and lower lactate concentration, anaerobic metabolic rate, and minute ventilation for equal power output.

    Conclusions: The new KL position can be recommended due to improved respiratory function but may impede performance. Generalization of results to XCSS athletes with reduced trunk muscle control may be limited, but these results can serve as a control for future studies of para-athletes.

  • 26.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Laaksonen, Marko S.
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Holmberg, L. Joakim
    Linköpings Universitet.
    Evaluation of two sitting positions in Cross-Country Sit-Skiing2016In: ICSS 2016 - International Congress on Science and Skiing, Arlberg, Austria, 10-15th December., 2016Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION

    In cross-country sit-skiing (CCSS) athletes with reduced trunk control mainly sit with their knees higher than the hips (KH) to increase trunk stability. To improve the spine curvature by reducing kyphosis a new sitting position was created where the knees are lower than the hips by help of a forward trunk support (KL). The aim of this study was to evaluate the new KL position and compare it to KH in terms of physiological and biomechanical measurements as well as musculoskeletal simulations.

    METHODS

    Five abled-bodied female cross-country skiers (62.6±8.1kg, 1.67±0.05m) performed two sets of tests; one in each sitting position on a skiing ergometer (ThoraxTrainer A/S, Denmark). Each test comprised a 30s all-out test (AO), an incremental submaximal test (4 to 6 x 3 min, SUB1-SUB6) and a maximal time-trial test of 3 min (MAX). During SUB and MAX external power and kinematics were measured. Metabolic rates (MR) were calculated from oxygen consumption and lactate concentrations.

    The AnyBody Modelling system (AMS 6.0, Anybody Technology A/S, Denmark) were used to simulate full-body musculoskeletal models over 4 poling cycles of SUB2, SUB4 and MAX. From the simulations muscular metabolic rate (mMR) and musculo-skeletal efficiency (ME) were computed (Holmberg et al., 2013).

    RESULTS & DISCUSSION

    The performance (W/kg) was higher in KH (p < 0.01) in both AO (24%) and MAX (32%). KL had more flexed knee, more extended hip and less kyphosis in trunk, while KH had larger range of motion (ROM) in hip and larger flexion and ROM in spine at SUB4 and MAX. Gross efficiency (GE) was higher in KH than KL. The total MR and ratio of anaerobic MR to total MR were higher in KL at SUB3 and SUB4.

    Simulations showed that 4 subjects had higher ME in KH for both SUB4 and MAX, though no statistical significance were observed. mMR were higher for KL at SUB2 and SUB4 but it was higher for KH at MAX. The ratio of mMR in body parts to total mMR showed higher ratio for KL in arm-shoulders (6.7-9.1%) and higher ratio for KH in trunk (3.7-4.6%) and hip-legs (3.0-4.6%).

    CONCLUSION

    The physiological results were comparable to others (Lajunen, 2014 & Verellen et al, 2012) and the simulation results were novel by showing how the motion of the trunk contributes to the total metabolic rate. KH position showed higher performance and GE while the KL position indicated higher mMR for arm-shoulders, and had also higher anaerobic MR. Therefore the KH position is favorable for abled-bodied athletes because KL limits trunk motion.

    REFERENCES

    Holmberg, L. J. et al. (2013). Comput Methods Biomech Biomed Engin16(9), 987-992. Lajunen, K. (2014). Effect of sitting posture on sit-skiing economy. Bachelor’s thesis, University of Jyväskylä.Verellen, J. et al. (2012). Eur J Appl Physiol, 112(3), 983-989.

  • 27.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Steffensen, Daniela
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Swarén, Mikael
    Swedish Unit of Metrology in Sports, Department of Sports, Fitness and Medicine, Dalarna University, Falun, Sweden.
    Danvind, Jonas
    Mittuniversitetet, Institutionen för kvalitets- och maskinteknik.
    The impact of the arms in para alpine slalom skiing2020Conference paper (Refereed)
    Abstract [en]

    In para-alpine skiing the rules says that athletes which are not able to hold and use a pole is eligible to compete. This is sometimes a hard task for classifiers to determine. The aim of this study was to increase the knowledge of the biomechanics in order to inform the development towards evidence classification system. The participants, 1 para-alpine skier (17 year with congential dysmelia left forearm, world cup level) and 10 able-bodied alpine skiers (18,3 ± 1,7 years national junior skiers at national level), performed a slalom course in three different conditions, using 2 poles, one pole and no poles. During these races time and full-body kinematics was measured using 12 IMU sensors (Myomotion, Noraxon Inc., USA). The results showed that reduced number of poles increased the race-time for able-bodied athletes. For able-bodied skiers both arm and leg kinematics was impacted by number of poles. No poles gave a more up-right position and a less dynamic technique. For the para-alpine skier no difference in race-time was shown between 1 pole and 2 pole condition, while the no pole condition was slower. The kinematics for the 1 pole condition was significantly different between the para-athlete compared to the able-bodied group for many body angles, showing a more crunched body position and larger range of motion for the para-athletes. To conclude, the number of poles impact race-time and kinematics of both arms and legs. Also, the balance ability seem to be affected by reduced number of poles.

  • 28.
    Lund Ohlsson, Marie
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Stöggl, T.
    Danvind, Jonas
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling (-2013).
    Asymmetry case study during skiing in the diagonal stride using a lower leg prosthesis2012Conference paper (Refereed)
  • 29.
    Oskarsson, Johanna
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Fjellström, Sanna
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Hansen, Elisabeth
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Differences in Special Olympics athletes and non-athletes with intellectual disability: physical activity, strength and aerobic fitness2023In: European Journal of Adapted Physical Activity, E-ISSN 1803-3857, Vol. 16, no 7Article in journal (Refereed)
    Abstract [en]

    Adults with intellectual disability (ID) have higher degree of sedentary lifestyle and participate in physical activity less compared to the general population. The aim of this cross-sectional study was to analyse if participation in Special Olympics increase the level of physical activity (PA) and influence physical health aspects such as BMI, muscular strength and aerobic fitness for people with ID. Data were analysed from the Special Olympics Sweden Invitational Games 2020, on athletes (n=38) and non-athletes with ID (n=20), of strength (partial sit-up-, seated push-up-, handgrip- and timed sit to stand test), aerobic fitness (2 min step up test), BMI and a PA-questionnaire. Athletes showed higher levels of PA moderate intensity, both groups had high BMI, low levels of aerobic fitness and strength. This study indicate that Special Olympics athletes and non-athletes with ID need to increase their physical activity of both strength training and PA higher intensity to improve physical health aspects.

  • 30.
    Parry, Henry
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Buskqvist, Alfred
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Erlandsson, Petter
    Öhrman, Christian
    Lindblom, Hampus
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskap.
    McGawley, Kerry
    Mittuniversitetet, Institutionen för hälsovetenskap.
    The influence of a rocking-motion device built into classic cross-country roller-ski bindings on biomechanical, physiological and performance outcomes2021In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 24, no 1, article id 24Article in journal (Refereed)
    Abstract [en]

    This study aimed to determine whether the recently developed Flow Motion Technology® roller-ski prototype could improve indicators of performance during sub-maximal and maximal cross-country roller skiing. Thirteen national and international cross-country skiers completed 2 experimental trials: 1 with Flow Motion Technology® activated, allowing a rocking motion between the foot and ski binding, and 1 with the foot fixed in a traditional manner. Each trial included 2 sub-maximal bouts using the diagonal-stride and double-poling sub-techniques, as well as a double-poling maximal velocity test and a diagonal-stride 6-min time trial. There were no differences in performance between Flow Motion Technology® and traditional roller skiing during the maximal velocity test or the time trial. However, reductions in mean plantar force during sub-maximal diagonal stride (p = 0.011) and ankle range of motion during sub-maximal (p = 0.010) and maximal (p = 0.041) diagonal stride were observed with Flow Motion Technology® versus traditional roller skiing. This, together with a reduced minimum horizontal distance of the hips in front of the ankles during sub-maximal double poling (p = 0.001), indicated impaired technique with Flow Motion Technology®, which may have contributed to the trend for reduced gross efficiency during double poling with Flow Motion Technology® (pη2 = 0.214). Significant physiological differences included a reduced sub-maximal double poling respiratory exchange ratio (p = 0.03) and a greater maximal heart rate during the time trial (p = 0.014) with Flow Motion Technology®. We conclude that the application of Flow Motion Technology® requires further examination before use in training and competition. 

  • 31.
    Rispal, Gauthier
    et al.
    Mid Sweden Univ, Swedish Winter Sports Res Ctr, Dept Hlth Sci, Östersund, Sweden.; Univ Aix Marseille, Fac Sport Sci, Marseille, France..
    Severin, Anna Cecilia
    Norwegian Univ Sci & Technol, Ctr Elite Sports Res, Dept Neuromed & Movement Sci, Trondheim, Norway..
    Baumgart, Julia Kathrin
    Norwegian Univ Sci & Technol, Ctr Elite Sports Res, Dept Neuromed & Movement Sci, Trondheim, Norway..
    Lund Ohlsson, Marie
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Mid Sweden Univ, Swedish Winter Sports Res Ctr, Dept Hlth Sci, Östersund, Sweden..
    Staunton, Craig A.
    Mid Sweden Univ, Swedish Winter Sports Res Ctr, Dept Hlth Sci, Ostersund, Sweden.; Swedish Winter Sports Res Ctr, Östersund, Sweden..
    Performance and micro-pacing strategies in sit para-biathlon2023In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 41, no 7, p. 646-653Article in journal (Refereed)
    Abstract [en]

    This study investigated micro-pacing strategies during sit para-biathlon. Six elite sit para-biathletes wore a positioning system device during the world-championships in three different competition formats (Sprint, Middle-distance, and Long-distance). Total Skiing Time (TST), penalty-time, shooting-time, and Total Race Time (TRT) were analysed. One-way analyses of variance were used to compare the relative contributions of TST, penalty-time, and shooting-time to TRT across the three race formats. Statistical parametric mapping (SPM) was used to determine the course positions (clusters) where instantaneous skiing speed was significantly associated with TST. The contribution of TST to TRT was lower for the Long-distance (80 & PLUSMN; 6%) compared to the Sprint (86 & PLUSMN; 5%) and Middle-distance (86 & PLUSMN; 3%) races, however this difference was not statistically significant (p > 0.05). The proportional contribution of penalty-time to TRT was significantly greater (p < 0.05) for the Long-distance (13 & PLUSMN; 6%) compared to the Sprint (5 & PLUSMN; 4%) and Middle-distance (4 & PLUSMN; 3%) races. Statistical parametric mapping (SPM) revealed specific clusters where instantaneous skiing speed was significantly associated with TST. For example, over all laps during the Long-distance race, the fastest athlete gained 6.5 s over the slowest athlete in the section with the steepest uphill. Overall, these findings can provide insights into pacing strategies and help para-biathlon coaches and athletes optimise training programmes to improve performance.

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  • 32.
    Skoglund, Per
    et al.
    Mittuniversitetet, Avdelningen för kvalitetsteknik, maskinteknik och matematik.
    Lund Ohlsson, Marie
    Mittuniversitetet, Avdelningen för hälsovetenskap.
    Danvind, Jonas
    Mittuniversitetet, Avdelningen för kvalitetsteknik, maskinteknik och matematik.
    Lower Leg Prosthesis for Cross-Country Skiing Classical Technique2013Conference paper (Refereed)
  • 33.
    Sutton, Peter
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskaper (HOV).
    Röijezon, Ulrik
    Reduced shoulder proprioception due to fatigue after repeated handball throws and evaluation of test–retest reliability of a clinical shoulder joint position test2022In: Shoulder & Elbow, ISSN 1758-5732Article in journal (Refereed)
    Abstract [en]

    Background: Proprioception is vital for motor control and can be disturbed, for example, due to fatigue or injury. Clinical feasible, reliable and valid tests of shoulder proprioception are warranted. The aim was to investigate the effects of local fatigue on shoulder proprioception and the reliability of a feasible joint position sense test using an experimental repeated measures design. Method: Forty participants repeated a shoulder joint position sense test to assess test–retest reliability. The test was then utilized on a subgroup of handball players who were subjected to five bouts of a repeated throwing task with the dominant hand. The effect of local fatigue was investigated by comparing the fatigued with the non-fatigued shoulder. Results: There was a significant interaction for the arm × bout (p = 0.028, ηp2 = 0.20) and a significant effect for the arm (p = 0.034, ηp2 = 0.35) with a significant decrease in joint position sense for the throwing arm compared to the non-throwing arm. The intraclass correlation coefficient was 0.78 (95% CI = [0.57; 0.89]). The standard error of measurement between trials was 0.70° (range: 0.57°–0.90°). Discussion: The results indicate that repeated throwing to fatigue disturbs shoulder joint position sense. Assessment with the modified test showed acceptable reliability and can be a valuable assessment tool in the clinic. 

  • 34.
    Vikberg, Sanna
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Hölltä, Jessica
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Zingmark, Magnus
    Östersunds kommun.
    Flygare Wallén, Eva
    Östersunds kommun.
    Hansen, Elisabeth
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Nordström, Anna
    Department of Public Health and Clinical Medicine, Section for Sustainable Health, Umeå University, Umeå, Sweden.
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Adapted internet-based training program improves exercise accessibility for people with intellectual disabilities2021Conference paper (Refereed)
    Abstract [en]

    Introduction and objective 

    Individuals with intellectual disability (ID) are less physically active than people without ID, and rarely or never reach the recommended daily dose of physical activity level. People with ID have a higher BMI than their peers and therefore a higher risk of obesity causing cardiovascular diseases. The overall objective was to determine the effectiveness on health and user experience of a 12-week, internet-based training program, customized for people with ID. 

    Methods 

    Participants with ID living in communal settings (n=27, 48% female, age = 36.4±9.56 years) were recruited for a training study including 50 minutes training 3 times a week in 12 weeks. Staff working with these participants (n=7, 57% female) were recruited for interviews. Questionnaires were used to evaluate enjoyment, quality of life and physical activity level, along with interviews. Body composition was measured as well as waist circumference. 

    Results 

    This study showed that 85% of the participants completed the web-based training. The level of physical activity (PA) increased during this period and positive changes in health outcomes were observed, for example a significant decrease in fat mass by a mean of 1.9kg ±2.4. The study also high-lighted barriers and facilitators for people with ID to use web-based training, along with perspectives and experiences on health and exercise among the staff within the supported housings. 

    Conclusion 

    A web-based training program is a new way to increase level of PA for people with ID. This study showed that web-based training program is an effective tool to improve health parameters, reduces hinders such as transport. Moreover, it is an easy way for staff to enhance PA in their work. This study present how web-based training was appreciated by many but not all participants ID which would probably be the same for people in general. The study was performed during the Covid-19 pandemic, which might have influenced the interest of the study in a positive manner. 

     

    Individuals with ID can be difficult to reach in health care. Barriers such as transport, less knowledge in health literacy and difficulties in seeking care are examples why. A web based exercise program is one of many parameters that can help to improve health and an effective way for health care to reach this target group in a cost effective manner. 

  • 35.
    Wedeking, Daniela
    et al.
    Mittuniversitetet, Institutionen för hälsovetenskap.
    Swarén, Mikael
    Swedish Olympic Academy, KTH Royal Institute of Technology, Stockholm, Sweden.
    Danvind, Jonas
    Mittuniversitetet, Institutionen för kvalitets- och maskinteknik.
    Lund Ohlsson, Marie
    Mittuniversitetet, Institutionen för hälsovetenskap.
    The influence of arm and ski pole during alpine skiing2019Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION: Research investigating the correlation between impairment and key performance indicators in para-alpine skiing is needed for a future evidence based classification system (Tweedy and Vanlandewijck 2011). Only a little research in para-alpine skiing exists, especially in the standing classes LW5/7 and LW6/8 (impairment of one or two arms). The use of arms and poles affects performance in alpine skiing[OM1]  but how underlying biomechanical parameters as kinematics and kinetics are related to performance has to the authors knowledge not been studied before.

    PURPOSE: The purpose of this study was to further the understanding of slalom skiing with two ski poles, one pole or without poles (c2, c1, c0) by investigating the biomechanical differences (kinematics and foot plantar pressure) for able-bodied athletes.

    METHODS: Ten able-bodied right-handed junior skiers on national level were tested in three conditions - c0, c1, c2, while skiing a slalom course (28 gates, 62 m vertical drop). 3D kinematic data were collected at 200 Hz by 12 inertial motion units (Myomotion, Noraxon Inc, USA) placed on head, trunk, pelvis, arms and legs. Ski-time was measured with timing gates (XS Crystal Synchronization, Brower Timing Systems, USA) and kinetics were measured with pressure insoles (Pedar, Novel GmbH, Germany) placed inside each ski boot. Normal ground reaction force (nGRF) and relative force time integrals (relFTI) were calculated according to Melai et. Al (2011). Kinematics and plantar pressure were analysed over three right and left turns and averaged for each condition. Right turn and left turn were distinguished at the time point where the shank was standing vertical.

    RESULTS: Time analysis showed that time increased with the use of less ski poles, mean difference between c1c2 of 1.27 ± 1.69 s (p=0.001) and between c0c1 of 0.73 ± 1.95 s (p=0.003[OM2] ). Kinematic analysis showed that different approaches were used to attack a slalom gate in condition c1 and c0, for example slalom-attack, giant slalom attack or opposite arm attack. Interquartile range and median of the body angles [OM3] differed between conditions, e.g. lower median (indicate less deviation from anatomical  basic position[OM4] ) in c0 and mostly lower than in c1 and c2. Furthermore, relFTI was related to the turning side (right or left turn) and showed largest asymmetry for condition c1.

    CONCLUSION: Reduced balance due to missing ski pole/s lead to compensatory movements in the upper body and asymmetry in foot plantar pressure. This reduced the ability for a controlled turn. Whether or not only reduced balance or also the skiers low experience of skiing with reduced number of poles influenced the performance remains unclear.

    REFERENCES

    Melai, Tom, T. Herman IJzerman, Nicolaas C. Schaper, Ton L.H. de Lange, Paul J.B. Willems, Kenneth Meijer, Aloysius G. Lieverse, and Hans H.C.M. Savelberg. 2011. ‘Calculation of Plantar Pressure Time Integral, an Alternative Approach’. Gait & Posture 34 (3): 379–83. https://doi.org/10.1016/j.gaitpost.2011.06.005.

    Tweedy, S. M., and Y. C. Vanlandewijck. 2011. ‘International Paralympic Committee Position Stand--Background and Scientific Principles of Classification in Paralympic Sport’. British Journal of Sports Medicine 45 (4): 259–69. https://doi.org/10.1136/bjsm.2009.065060.

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