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A Musculoskeletal Full‐body Simulation of Cross‐Country Skiing
Linköpings Universitet.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.ORCID iD: 0000-0001-5317-2779
2008 (English)In: 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) Published
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.

Place, publisher, year, edition, pages
London: The Institution of Mechanical Engineers , 2008. Vol. 222, no P1, p. 11-22
Keywords [en]
biomechanics, double poling, ergometer, inverse dynamics
National Category
Computational Mathematics
Identifiers
URN: urn:nbn:se:miun:diva-9934DOI: 10.1243/17543371JSET10ISI: 000207664600003Scopus ID: 2-s2.0-84990348576OAI: oai:DiVA.org:miun-9934DiVA, id: diva2:240698
Projects
Nationellt vintersportcentrumAvailable from: 2009-09-29 Created: 2009-09-29 Last updated: 2018-02-08Bibliographically approved
In thesis
1. New methods for movement technique development in cross-country skiing using mathematical models and simulation
Open this publication in new window or tab >>New methods for movement technique development in cross-country skiing using mathematical models and simulation
2009 (English)Licentiate 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.

Place, publisher, year, edition, pages
Sundsvall: Mittuniversitetet, 2009
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 41
National Category
Computational Mathematics
Identifiers
urn:nbn:se:miun:diva-10041 (URN)978-91-86073-53-4 (ISBN)
Presentation
2009-11-11, Q221, Mid Sweden Univ, Campus Östersund, Östersund, 13:00 (English)
Supervisors
Available from: 2009-10-15 Created: 2009-10-15 Last updated: 2016-06-20Bibliographically approved
2. Double Poling Incross-Country Skiing: Biomechanical and Physiological Analysis of Sitting and Standing Positions
Open this publication in new window or tab >>Double Poling Incross-Country Skiing: Biomechanical and Physiological Analysis of Sitting and Standing Positions
2018 (English)Doctoral 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.

Abstract [sv]

Stakning är en delteknik inom längdskidåkning som har ökat i intresse de senaste årtiondena, bland annat har eliten ökat andelen stakning markant. Längdskidåkning i sit-ski utövas av individer med funktionsnedsättning i benen och/eller bålen. I denna sport används stakning uteslutande för att ta sig framåt. Tekniken, eller rörelsemönstret, är en faktor för prestation inom dessa sporter. Tekniken kan också påverka risken för överbelastningsskador.

Denna avhandling har studerat stakning med det övergripande målet att utöka förståelsen för tekniken i både stående (artikel I-II) och sittande positioner (artikel III-VI samt resultat i avhandlingen A-B). Tekniken har studerats med hjälp av biomekaniska och fysiologiska mätningar i laboratorium samt muskuloskelettära simuleringar. Tre experimentella studier har genomförts med försökspersoner utan funktionsnedsättningar. Två studier har genomförts med försökspersoner med funktionsnedsättningar,  en studie med en försöksperson med tillväxtstörning (förkortade ben) och en studie med en försöksperson med en fullständig ryggmärgsskada vid bröstkota 4.

Artikel I-II visade att stående stakningsteknik med böjda knän ökar prestationen under ett 30 s maximalt test. Med mer böjda ben ökas det metabola muskulära arbetet (beräknat genom simuleringar) och verkningsgraden av det muskuloskelettära systemet minskar jämfört med stakning med raka ben. Denna studie visar exempel på att samma teknik inte uppnådde både högst prestation och effektivitet.

En person med förlamning i nedre delen av bålen och benen behöver stabilitet för bålen av sin sit-ski. Detta uppnås vanligtvis genom att placera knän högre än höfterna (KH). Dock kan denna position skapa en stor flexion i ryggraden, vilket är en risk för skador i ländrygg och axlar. För personer med full muskelfunktion i höft och bål är den vanligaste sittposition knäsittande (KLnoS). Denna avhandling har möjliggjort knäsittande sittposition för personer med förlamning i nedre delen av bålen och benen genom ett stöd framifrån för bröstkorgen i sit-skin (KL).

För sittande positioner för personer utan nedsatt muskelfunktion i höft och bål påvisas att högst prestation uppnås när störst andel muskelmassa arbetar och rörelseomfånget i höft och ryggrad är störst, knän lägre än höft och utan stöd för bålen från sit-skin (KLnoS) (A). När arbetande muskelmassa minskar, minskar också prestationen. Prestationen var lägre i sittposition med knän högre än höfterna (KH) och än lägre i sittposition knän lägre än höft och med ett stöd för bröstkorgen från sit-skin (KL) (IV,V). Med lägre andel aktiv muskelmassa så ökade det relativa anaeroba metabola arbetet, medan det absoluta aeroba metabola arbetet och gross-efficiency (GE) var liknande. Sitt-positionen KH visade på högre flexion av ryggraden, högre metabolt muskelarbete i bålen och högre ledreaktionskrafter i ländryggen, medan sittpositionen KL visade på högre metabolt muskelarbete i axlar och armar och högre ledreaktionskrafter i axlarna (VI). Högre reaktionskraft i ländryggen kan vara kopplat till högre risk för överbelastningskada.

För en försöksperson med förlamning från revbenen och nedåt, var också prestationen högre när bröstkorgens position ej var fix, högre i KH jämfört med KL och knän högre än höft och ett bröststöd (KHS) (B). Resultaten visar också att det inte bara är biomekaniken som påverkar prestationen. I sittpositionerna där bröstkorgens position var fix, KHS och KL, böjdes ryggen bakåt vid stakfasen start och prestationen var högre i KHS. Avhandlingen diskuterar att prestationen påverkas av att låg position av benen medför ökad effekt av gravitationen på blodflödet. Denna effekt blir stor eftersom förlamad muskulatur också har nedsatt funktion av venernas pumpförmåga att återföra blodet till hjärtat. För en person utan förlamningen i benen visade sig det omvända, sittpositionen KL vara mer ekonomisk än sittposition KHS (III).

Sammanfattningsvis, denna avhandling har visat på att flera faktorer för att välja teknik inom stående stakning och sittposition inom sittande längdskidåkning i sit-ski. Samma teknik är inte optimal för alla individer. För stående indikeras att både ökad prestation och verkningsgrad inte uppnås när benen arbetar mer. För sittande är det viktigt att använda sig av höften och bålens muskelarbete och inte sitta fast varken för mycket eller för lite i sit-skin. Avhandlingen visar exempel på att en person med förlamning i nedre bål och ben, har fördel av bålrörelse trots sin förlamning och att benens position påverkar prestationen.

Klassificering inom parasport ska bedöma hur funktionsnedsättningen påverkar idrottsprestationen. Simuleringsmetoderna som använts i denna avhandling kan vara av intresse för utveckling av klassificeringssystem eftersom de har visat hur olika muskelgrupper påverkar prestationen.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2018. p. 95
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 275
Keywords
blood lactate concentration, cross-country sit-skiing, impairment, internal kinetics, inverse dynamics simulations, joint reaction forces, kinematics, metabolic rate, musculoskeletal modelling, musculoskeletal efficiency, nordic skiing, oxygen uptake, para-skiing, respiration, skiing efficiency.
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-32733 (URN)978-91-88527-38-7 (ISBN)
Public defence
2018-03-02, Q221, Kunskapens väg 8, Östersund, 11:00 (English)
Opponent
Supervisors
Note

Vid tidpunkten för disputationen var följande delarbeten opublicerade: delarbete 5 inskickat, delarbete 6 inskickat.

At the time of the doctoral defence the following papers were unpublished: paper 5 submitted, paper 6 submitted.

Available from: 2018-02-08 Created: 2018-02-08 Last updated: 2018-03-23Bibliographically approved

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Holmberg, JoakimLund, Marie

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