Mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.

<h4>Objectives</h4>The aim of this study was to examine the effect of speed on mechanical energy fluctuations and propulsion mechanics in the double-poling (DP) technique of cross-country skiing.<h4>Methods</h4>Kinematics and dynamics were acquired while fourteen male skiers...

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Autores principales:	Jørgen Danielsen, Øyvind Sandbakk, David McGhie, Gertjan Ettema
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/a7e57c1fc3e94dc284db2ea70296df5d
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spelling	oai:doaj.org-article:a7e57c1fc3e94dc284db2ea70296df5d2021-12-02T20:09:04ZMechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.1932-620310.1371/journal.pone.0255202https://doaj.org/article/a7e57c1fc3e94dc284db2ea70296df5d2021-01-01T00:00:00Zhttps://doi.org/10.1371/journal.pone.0255202https://doaj.org/toc/1932-6203<h4>Objectives</h4>The aim of this study was to examine the effect of speed on mechanical energy fluctuations and propulsion mechanics in the double-poling (DP) technique of cross-country skiing.<h4>Methods</h4>Kinematics and dynamics were acquired while fourteen male skiers performed roller-skiing DP on a treadmill at increasing speeds (15, 21 and 27 km∙h-1). Kinetic (Ekin), potential (Epot), and total (Ebody) body mechanical energy and pole power (Ppole) were calculated. Inverse dynamics was used to calculate arm power (Parm). Trunk+leg power (PT+L) was estimated, as was the power associated with body movements perpendicular to goal-direction ([Formula: see text]).<h4>Results</h4>Ekin and Epot fluctuated out-of-phase throughout the cycle, at first sight indicating that pendulum-like behaviour occurs partly in DP. However, during the swing phase, the increase in Epot (body heightening) was mainly driven by positive PT+L, while the decrease in Ekin was lost to rolling friction, and during the poling phase, considerable positive Parm generation occurs. Thus, possible exchange between Ekin and Epot seem not to occur as directly and passively as in classic pendulum locomotion (walking). During the poling phase, [Formula: see text]fluctuated out-of-phase with Ppole, indicating a transfer of body energy to Ppole. In this way, power generated by trunk+leg mainly during the swing phase (body heightening) can be used in the poling phase as pole power. At all speeds, negative PT+L occurred during the poling phase, suggesting energy absorption of body energy not transferred to pole power. Thus, DP seem to resemble bouncing ball-like behaviour more than pendulum at faster speeds. Over the cycle, Parm contribution to Ppole (external power) was 63% at 15 km∙h-1 and 66% at 21 and 27 km∙h-1, with the remainder being PT+L contribution.<h4>Conclusions</h4>When speed increases in level DP, both power production and absorption by trunk+leg actions increase considerably. This enhanced involvement of the legs at faster speeds is likely a prerequisite for effective generation of pole power at high speeds with very short poling times. However, the relative trunk+leg power contribution did not increase at the speeds studied here.Jørgen DanielsenØyvind SandbakkDavid McGhieGertjan EttemaPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 16, Iss 7, p e0255202 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Jørgen Danielsen Øyvind Sandbakk David McGhie Gertjan Ettema Mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.
description	<h4>Objectives</h4>The aim of this study was to examine the effect of speed on mechanical energy fluctuations and propulsion mechanics in the double-poling (DP) technique of cross-country skiing.<h4>Methods</h4>Kinematics and dynamics were acquired while fourteen male skiers performed roller-skiing DP on a treadmill at increasing speeds (15, 21 and 27 km∙h-1). Kinetic (Ekin), potential (Epot), and total (Ebody) body mechanical energy and pole power (Ppole) were calculated. Inverse dynamics was used to calculate arm power (Parm). Trunk+leg power (PT+L) was estimated, as was the power associated with body movements perpendicular to goal-direction ([Formula: see text]).<h4>Results</h4>Ekin and Epot fluctuated out-of-phase throughout the cycle, at first sight indicating that pendulum-like behaviour occurs partly in DP. However, during the swing phase, the increase in Epot (body heightening) was mainly driven by positive PT+L, while the decrease in Ekin was lost to rolling friction, and during the poling phase, considerable positive Parm generation occurs. Thus, possible exchange between Ekin and Epot seem not to occur as directly and passively as in classic pendulum locomotion (walking). During the poling phase, [Formula: see text]fluctuated out-of-phase with Ppole, indicating a transfer of body energy to Ppole. In this way, power generated by trunk+leg mainly during the swing phase (body heightening) can be used in the poling phase as pole power. At all speeds, negative PT+L occurred during the poling phase, suggesting energy absorption of body energy not transferred to pole power. Thus, DP seem to resemble bouncing ball-like behaviour more than pendulum at faster speeds. Over the cycle, Parm contribution to Ppole (external power) was 63% at 15 km∙h-1 and 66% at 21 and 27 km∙h-1, with the remainder being PT+L contribution.<h4>Conclusions</h4>When speed increases in level DP, both power production and absorption by trunk+leg actions increase considerably. This enhanced involvement of the legs at faster speeds is likely a prerequisite for effective generation of pole power at high speeds with very short poling times. However, the relative trunk+leg power contribution did not increase at the speeds studied here.
format	article
author	Jørgen Danielsen Øyvind Sandbakk David McGhie Gertjan Ettema
author_facet	Jørgen Danielsen Øyvind Sandbakk David McGhie Gertjan Ettema
author_sort	Jørgen Danielsen
title	Mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.
title_short	Mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.
title_full	Mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.
title_fullStr	Mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.
title_full_unstemmed	Mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.
title_sort	mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.
publisher	Public Library of Science (PLoS)
publishDate	2021
url	https://doaj.org/article/a7e57c1fc3e94dc284db2ea70296df5d
work_keys_str_mv	AT jørgendanielsen mechanicalenergyandpropulsionmechanicsinrollerskiingdoublepolingatincreasingspeeds AT øyvindsandbakk mechanicalenergyandpropulsionmechanicsinrollerskiingdoublepolingatincreasingspeeds AT davidmcghie mechanicalenergyandpropulsionmechanicsinrollerskiingdoublepolingatincreasingspeeds AT gertjanettema mechanicalenergyandpropulsionmechanicsinrollerskiingdoublepolingatincreasingspeeds
_version_	1718375142089818112

Mechanical energy and propulsion mechanics in roller-skiing double-poling at increasing speeds.

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