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The rolling resistances of roller skis and their effects on human performance during treadmill roller skiing
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik och hållbar utveckling. (Sporttech, Swedish Winter Sports Research Centre)
Mittuniversitetet, Fakulteten för humanvetenskap, Institutionen för hälsovetenskap.
2010 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical performance in a laboratory environment using classical and freestyle techniques on roller skis. For elite athletes the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance coefficient, µR, in order to allow correct comparisons between the results, as well as providing the opportunity to study work economy between different athletes, test occasions and core techniques.

Thus, one of the aims of this thesis was to evaluate how roller skis’ µR is related to warm-up, mass, velocity and inclination of the treadmill. It was also necessary to investigate the methodological variability of the rolling resistance measurement system, RRMS, specially produced for the experiments, with a reproducibility study in order to indicate the validity and reliability of the results.

The aim was also to study physiological responses to different µR during roller skiing with freestyle and classical roller skis and techniques on the treadmill as a case in which all measurements were carried out in stationary and comparable conditions.

Finally, the aim was also to investigate the work economy of amateurs and female and male junior and senior cross-country skiers during treadmill roller skiing, i.e. as a function of skill, age and gender, including whether differences in body mass causes significant differences in external power per kg due to differences in the roller skis’ µR.

The experiments showed that during a warm-up period of 30 minutes, µR decreased to about 60-65% and 70-75% of its initial value for freestyle and classical roller skis respectively. For another 30 minutes of rolling no significant change was found. Simultaneous measurements of roller ski temperature and mR showed that stabilized mR corresponds to a certain running temperature for a given normal force on the roller ski. The study of the influence on mR of normal force, velocity and inclination produced a significant influence of normal force on mR, while different velocities and inclinations of the treadmill only resulted in small changes in mR. The reproducibility study of the RRMS showed no significant differences between paired measurements with either classical or the freestyle roller skis.

The study of the effects on physiological variables of ~50% change in µR,showed that during submaximal steady state 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 significantly changed 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 final part of the thesis, which focused on work economy, found no significant difference between the four groups of elite competitors, i.e. between the two genders and between the junior and senior elite athletes. It was only the male amateurs who significantly differed among the five studied groups. The study also showed that the external power per kg was significantly different between the two genders due to differences in body mass and mR, i.e. the lighter female testing groups were roller skiing with a relatively heavier rolling resistance coefficient compared to the heavier testing groups of male participants.

Ort, förlag, år, upplaga, sidor
Sundsvall: Kopieringen Mid Sweden University , 2010. , s. 34
Serie
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 42
Nyckelord [en]
Blood lactate, cycle length, cycle rate, heart rate, oxygen uptake, performance, power, roller skis, rolling resistance, ratings of perceived exertion, work economy
Nationell ämneskategori
Idrottsvetenskap
Identifikatorer
URN: urn:nbn:se:miun:diva-10844ISBN: 978-91-86073-60-2 (tryckt)OAI: oai:DiVA.org:miun-10844DiVA, id: diva2:284045
Presentation
2010-01-13, Q341, Akademigatan 1, Mittuniversitetet, Östersund, 10:00 (Svenska)
Opponent
Handledare
Projekt
SporttechTillgänglig från: 2010-01-07 Skapad: 2010-01-04 Senast uppdaterad: 2011-09-05Bibliografiskt granskad
Delarbeten
1. Rolling resistance for treadmill roller skiing
Öppna denna publikation i ny flik eller fönster >>Rolling resistance for treadmill roller skiing
2008 (Engelska)Ingår i: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 11, nr 1, s. 23-29Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Modern treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical performance under laboratory conditions using classical and freestyle techniques on roller skis. The differences in performance between tests are quite small for elite athletes, and it is therefore of great importance to control the rolling resistance of the roller skis. Otherwise different physiological tests cannot be accurately compared.

This study shows that during a warm-up period of  30 minutes the coefficient of rolling resistance (µR) decreases to about 60-65% and 70-75% of its initial value for freestyle and classical roller skis respectively.

Simultaneous measurements of temperature and µR shows that stabilized rolling resistance corresponds to a certain running temperature for a given normal force on the roller ski.

Tests were also performed on the influence on µR of normal force, velocity and inclination. Normal forces produced significant influence on µR , while different velocities and inclinations of the treadmill only resulted in small changes in µR.

Ort, förlag, år, upplaga, sidor
Springer, 2008
Nyckelord
Incline, Normal force, Roller skis, Velocity, Warm up, Sport science, Sport technology, Idrottsvetenskap, Sportteknologi
Nationell ämneskategori
Maskinteknik Fysiologi Idrottsvetenskap
Identifikatorer
urn:nbn:se:miun:diva-6361 (URN)10.1007/s12283-008-0004-1 (DOI)4197 (Lokalt ID)4197 (Arkivnummer)4197 (OAI)
Projekt
Sportstech
Tillgänglig från: 2008-11-19 Skapad: 2008-11-19 Senast uppdaterad: 2018-01-12Bibliografiskt granskad
2. Roller ski rolling resistance and its effects on elite athletes’ performance
Öppna denna publikation i ny flik eller fönster >>Roller ski rolling resistance and its effects on elite athletes’ performance
2008 (Engelska)Ingår i: ENGINEERING OF SPORT 7, VOL 2, 2008, Vol. 11, nr 3, s. 393-400Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical fitness in a laboratory environment whilst performing classical and freestyle (skating) techniques on roller skis. For elite athletes the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance in order to allow the correct comparison between the results of different test occasions. In this study the roller skis’ rolling resistance has been measured using equipment on the ski-treadmill. The study investigates the influence of significant changes in rolling resistance on physiological variables. The results show that during submaximal exercise, heart rate, blood lactate, power and oxygen uptake are significantly changed by different rolling resistances, while there are no significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests show that time to exhaustion is significantly changed by different rolling resistances and this occurred without significant changes in maximal oxygen uptake and heart rate, and the influence on maximal power and ratings of perceived exertion were insignificant or small.

Nyckelord
lactate, heart rate, oxygen uptake, power, rolling resistance, time to exhaustion, Sport science, Sport technology, Idrottsvetenskap, Sportteknologi
Nationell ämneskategori
Idrottsvetenskap Fysiologi Maskinteknik
Identifikatorer
urn:nbn:se:miun:diva-7982 (URN)000259392700049 ()978-2-287-09412-5 (ISBN)
Konferens
ISEA 2008 Conference on Engineering of Sport 7, Jun 02-06, 2008, Biarritz, France
Projekt
Sportstech
Tillgänglig från: 2009-01-07 Skapad: 2009-01-07 Senast uppdaterad: 2018-01-13Bibliografiskt granskad
3. Work economy of amateur and elite cross-country skiers during treadmill roller skiing
Öppna denna publikation i ny flik eller fönster >>Work economy of amateur and elite cross-country skiers during treadmill roller skiing
Visa övriga...
2009 (Engelska)Ingår i: 4th Asia Pacific Congress on Sports Technology, APCST2009, 2009Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

This study focused on the work economy of cross-country skiers during treadmill roller skiing in the perspectives; skill, age and gender. The study was investigating the external power output from elevating the transported mass against gravity and overcoming the roller skis rolling resistance, and the internal power from measured oxygen uptake and energy consumption. The roller skis rolling resistance was measured with a fixture on the ski-treadmill and the results showed a significant correlation between normal force and rolling resistance. The results also showed that it was only the amateur skiers who significantly differed in work economy among the five studied groups.

Nationell ämneskategori
Idrottsvetenskap
Identifikatorer
urn:nbn:se:miun:diva-10062 (URN)13 978-1-921426-38-4 (ISBN)
Tillgänglig från: 2009-10-19 Skapad: 2009-10-19 Senast uppdaterad: 2011-09-05Bibliografiskt granskad

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