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The influence of grip on oxygen consumption and leg forces when using classical style roller skis
Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
2014 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, no 2, 301-310 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to investigate the influence of classical style roller skis' grip (static friction coefficients, μ S) on cross-country skiers' oxygen consumption and leg forces during treadmill roller skiing, when using the diagonal stride and kick double poling techniques. The study used ratcheted wheel roller skis from the open market and a uniquely designed roller ski with an adjustable camber and grip function. The results showed significantly (P≤0.05) higher oxygen consumption (∼14%), heart rate (∼7%), and lower propulsive forces from the legs during submaximal exercise and a shorter time to exhaustion (∼30%) in incremental maximal tests when using roller skis with a μ S similar to on-snow skiing, while there was no difference between tests when using different pairs of roller skis with a similar, higher μ S. Thus, we concluded that oxygen consumption (skiing economy), propulsive leg forces, and performance time are highly changed for the worse when using roller skis with a lower μ S, such as for on-snow skiing with grip-waxed cross-country skis, in comparison to ratcheted wheel roller skis with several times higher μ S.

Place, publisher, year, edition, pages
John Wiley & Sons, 2014. Vol. 24, no 2, 301-310 p.
Keyword [en]
adjustable grip, center of pressure, normal and tangential forces, ratcheted wheel, skiing economy, static friction
National Category
Sport and Fitness Sciences Mechanical Engineering Physiology
Identifiers
URN: urn:nbn:se:miun:diva-16445DOI: 10.1111/sms.12006ISI: 000332982700011Scopus ID: 2-s2.0-84896404410OAI: oai:DiVA.org:miun-16445DiVA: diva2:533603
Note

Published online 28 sep 2012

Available from: 2012-06-14 Created: 2012-06-14 Last updated: 2014-04-24Bibliographically approved
In thesis
1. Roller skis' rolling resistance and grip characteristics: influences on physiological and performance measures in cross-country skiers
Open this publication in new window or tab >>Roller skis' rolling resistance and grip characteristics: influences on physiological and performance measures in cross-country skiers
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of this thesis was to investigate roller ski characteristics; classical and freestyle roller skis’ rolling resistance coefficients (μR) and classical style roller skis’ static friction coefficients (μS), and to study the influence of different μR and μS on cross-country skiers’ performance and both physiological and biomechanical indices. The aim was also to study differences in skiing economy and efficiency between recreational skiers, female and male junior and senior elite cross-country skiers.The experiments showed that during a time period of 30 minutes of rolling on a treadmill (warm-up), μR decreased significantly (p<0.05) to about 60-65 % and 70-75 % of its initial value for freestyle and classical roller skis respectively. Also, there was a significant influence of normal force on μR, while different velocities and inclinations of the treadmill only resulted in small changes in μR.The study of the influence on physiological variables of a ~50 % change in μR showed that during submaximal steady rate exercise, external power, oxygen uptake, heart rate and blood lactate were significantly changed, while there were non-significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed and this occurred without a change in maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion was non-significant or small.The study of classical style roller skis μS showed values that were five to eight times more than the values of μS reported from on-snow skiing with grip-waxed cross-country skis.The subsequent physiological and biomechanical experiments with different μS showed a significantly lower skiing economy (~14 % higher v̇O2), higher heart rate, lower propulsive forces coming from the legs and shorter time to exhaustion (~30 %) when using a different type of roller ski with a μS similar to on-snow skiing, while there was no difference between tests when using different pairs of roller skis with a (similar) higher μS.The part of the thesis which focused on skiing economy and efficiency as a function of skill, age and gender, showed that the elite cross-country skiers had better skiing economy and higher gross efficiency (5-18 %) compared with the recreational skiers, and the senior elite had better economy and higher efficiency (4-5 %) than their junior counterparts, while no differences could be found between the genders.

Abstract [sv]

Syftet med denna avhandling var att undersöka fristils- och klassiska rullskidors rullmotståndskoefficienter (μR) och klassiska rullskidors statiska friktionskoefficienter (μS) samt effekter av olika μR och μS på längdskidåkares prestation vid rullskidåkning på rullande band. Syftet var även att undersöka s.k. åkekonomi och mekanisk verkningsgrad mellan motionärer och kvinnliga och manliga junior- och seniorlängdskidåkare på elitnivå.Experimenten visade att under en period av 30 minuters kontinuerligt rullande, på rullande band, så sjönk μR signifikant (p<0.05) till 60-65 % och 70-75 % av initiala värden, för fristils- respektive klassiska rullskidor. Undersökandet av olika normalkrafter, hastigheter och lutningars påverkan på μR resulterade i en signifikant, negativ korrelation för μR som funktion av normalkraft, medan olika hastigheter och lutningar endast medförde små förändringar av μR.Studien som undersökte fysiologiska effekter av olika μR visade, vid submaximala konstanta arbetsbelastningar, att yttre effekt, syreupptagning, hjärtfrekvens och blodlaktat förändrades signifikant vid ~50 % förändring av μR. Försökspersonernas frekvens och sträcka per frekvens samt skattning av upplevd ansträngning resulterade dock i mestadels icke signifikanta eller små förändringar. Protokollen med successivt ökande arbetsbelastning (maxtest) resulterade i signifikant förändrad tid till utmattning, vid ~50 % förändring av μR. Detta inträffade utan signifikant skillnad i maximal syreupptagning, hjärtfrekvens och blodlaktat, vilket även mestadels gällde för skattning av upplevd ansträngning.Experimenten som undersökte klassiska rullskidors μS visade att dessa erhöll värden som är fem till åtta gånger högre än vad som rapporterats från studier av μS på snö med fästvallade skidor.Den efterföljande studien som undersökte fysiologiska och biomekaniska influenser av olika μS visade, vid submaximala konstanta arbetsbelastningar, att åkekonomin försämrades (~14 % högre syreförbrukning), hjärtfrekvensen ökade, den framåtdrivande kraften från benen på rullskidorna minskade samt att det blev kortare tid till utmattning (~30 %), vid maxtest, när skidåkarna använde rullskidor med en μS i likhet med vad som rapporterats för skidåkning på snö. För arbetsförsöken med olika rullskidor av olika fabrikat med en högre, och likartad, μS förelåg ingen skillnad i de undersökta variablerna.Studien som undersökte åkekonomi och mekanisk verkningsgrad som funktion av prestationsnivå, ålder och kön, visade att elitskidåkarna hade bättre åkekonomi och verkningsgrad (5-18 %) i jämförelse med motionärerna, att seniorerna hade bättre åkekonomi och verkningsgrad (4-5 %) än juniorerna och att ingen skillnad kunde konstateras mellan könen.

Place, publisher, year, edition, pages
Östersund: Mid Sweden University, 2012
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 125
Keyword
Adjustable grip, blood lactate, centre of pressure, cycle length, cycle rate, economy, efficiency, friction coefficient, heart rate, normal force, OBLA, oxygen uptake, power, ratcheted wheel, ratings of perceived exertion, roller skis, rolling resistance, tangential force, time to exhaustion
National Category
Sport and Fitness Sciences Physiology Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-16446 (URN)978-91-87103-15-5 (ISBN)
Supervisors
Available from: 2012-06-14 Created: 2012-06-14 Last updated: 2012-08-01Bibliographically approved

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Ainegren, MatsCarlsson, PeterLaaksonen, Marko S.Tinnsten, Mats
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