Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength

The ground reaction forces (GRF) associated with competitive alpine skiing, which are relatively large, might be asymmetric during left and right turns due to asymmetries in the strength of the legs and torso and the present investigation was designed to evaluate this possibility. While skiing a sym...

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Main Authors: Jan Ogrin, Nejc Šarabon, Mads Kjær Madsen, Uwe Kersting, Hans-Christer Holmberg, Matej Supej
Format: Article
Language:English
Published: Frontiers Media S.A. 2021-03-01
Series:Frontiers in Physiology
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fphys.2021.577698/full
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spelling doaj-c430f5e2ef1d471db12827b35c84fbd82021-03-30T05:01:45ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2021-03-011210.3389/fphys.2021.577698577698Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular StrengthJan Ogrin0Nejc Šarabon1Nejc Šarabon2Mads Kjær Madsen3Uwe Kersting4Uwe Kersting5Hans-Christer Holmberg6Hans-Christer Holmberg7Matej Supej8Matej Supej9Faculty of Sport, University of Ljubljana, Ljubljana, SloveniaFaculty of Health Sciences, University of Primorska, Izola, SloveniaS2P, Science to Practice, Ltd., Laboratory for Motor Control and Motor Behavior, Ljubljana, SloveniaDepartment of Health Science and Technology, Sport Sciences – Performance and Technology, Aalborg University, Aalborg, DenmarkDepartment of Health Science and Technology, Sport Sciences – Performance and Technology, Aalborg University, Aalborg, DenmarkInstitute of Biomechanics and Orthopedics, German Sport University Cologne, Cologne, GermanyDepartment of Physiology and Pharmacology, Biomedicum C5, Karolinska Institute, Stockholm, SwedenChina Institute of Sport and Health Science, Beijing Sport University, Beijing, ChinaFaculty of Sport, University of Ljubljana, Ljubljana, SloveniaSwedish Winter Sports Research Centre, Mid Sweden University, Östersund, SwedenThe ground reaction forces (GRF) associated with competitive alpine skiing, which are relatively large, might be asymmetric during left and right turns due to asymmetries in the strength of the legs and torso and the present investigation was designed to evaluate this possibility. While skiing a symmetrical, 20-gate slalom course, the asymmetries of 9 elite alpine skiers were calculated on the basis of measurements provided by inertial motion units (IMU), a Global Navigation Satellite System and pressure insoles. In addition, specialized dynamometers were utilized to assess potential asymmetry in the strength of their legs and torso in the laboratory. In total, seven variables related to GRF were assessed on-snow and eight related to strength of the legs and torso in the laboratory. The asymmetries in these parameters between left and right turns on snow were expressed in terms of the symmetry (SI) and Jaccard indices (JI), while the asymmetries between the left and right sides of the body in the case of the laboratory measurements were expressed as the SIs. The three hypotheses to be tested were examined using multivariable regression models. Our findings resulted in rejection of all three hypotheses: The asymmetries in total GRF (H1), as well as in the GRF acting on the inside and outside legs (H2) and on the rear- and forefeet GRF (H3) during left and right turns were not associated with asymmetries in parameters related to muscular strength. Nevertheless, this group of elite slalom skiers exhibited significant asymmetry between their right and left legs with respect to MVC during ankle flexion (0.53 ± 0.06 versus 0.60 ± 0.07 Nm/kg, respectively) and hip extension (2.68 ± 0.39 versus 2.17 ± 0.26 Nm/kg), as well as with respect to the GRFs on the inside leg while skiing (66.8 ± 7.39 versus 76.0 ± 10.0 %BW). As indicated by the JI values, there were also large asymmetries related to GRF as measured by pressure insoles (range: 42.7–56.0%). In conclusion, inter-limb asymmetries in GRFs during elite alpine skiing are not related to corresponding asymmetries in muscular strength. Although our elite athletes exhibited relatively small inter-limb asymmetries in strength, their asymmetries in GRF on-snow were relatively large.https://www.frontiersin.org/articles/10.3389/fphys.2021.577698/fullbiomechanicsalpine skiinginertial suitGNSS-global navigation satellite systemGPS-global positional systempressure insoles
collection DOAJ
language English
format Article
sources DOAJ
author Jan Ogrin
Nejc Šarabon
Nejc Šarabon
Mads Kjær Madsen
Uwe Kersting
Uwe Kersting
Hans-Christer Holmberg
Hans-Christer Holmberg
Matej Supej
Matej Supej
spellingShingle Jan Ogrin
Nejc Šarabon
Nejc Šarabon
Mads Kjær Madsen
Uwe Kersting
Uwe Kersting
Hans-Christer Holmberg
Hans-Christer Holmberg
Matej Supej
Matej Supej
Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength
Frontiers in Physiology
biomechanics
alpine skiing
inertial suit
GNSS-global navigation satellite system
GPS-global positional system
pressure insoles
author_facet Jan Ogrin
Nejc Šarabon
Nejc Šarabon
Mads Kjær Madsen
Uwe Kersting
Uwe Kersting
Hans-Christer Holmberg
Hans-Christer Holmberg
Matej Supej
Matej Supej
author_sort Jan Ogrin
title Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength
title_short Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength
title_full Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength
title_fullStr Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength
title_full_unstemmed Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength
title_sort asymmetries in ground reaction forces during turns by elite slalom alpine skiers are not related to asymmetries in muscular strength
publisher Frontiers Media S.A.
series Frontiers in Physiology
issn 1664-042X
publishDate 2021-03-01
description The ground reaction forces (GRF) associated with competitive alpine skiing, which are relatively large, might be asymmetric during left and right turns due to asymmetries in the strength of the legs and torso and the present investigation was designed to evaluate this possibility. While skiing a symmetrical, 20-gate slalom course, the asymmetries of 9 elite alpine skiers were calculated on the basis of measurements provided by inertial motion units (IMU), a Global Navigation Satellite System and pressure insoles. In addition, specialized dynamometers were utilized to assess potential asymmetry in the strength of their legs and torso in the laboratory. In total, seven variables related to GRF were assessed on-snow and eight related to strength of the legs and torso in the laboratory. The asymmetries in these parameters between left and right turns on snow were expressed in terms of the symmetry (SI) and Jaccard indices (JI), while the asymmetries between the left and right sides of the body in the case of the laboratory measurements were expressed as the SIs. The three hypotheses to be tested were examined using multivariable regression models. Our findings resulted in rejection of all three hypotheses: The asymmetries in total GRF (H1), as well as in the GRF acting on the inside and outside legs (H2) and on the rear- and forefeet GRF (H3) during left and right turns were not associated with asymmetries in parameters related to muscular strength. Nevertheless, this group of elite slalom skiers exhibited significant asymmetry between their right and left legs with respect to MVC during ankle flexion (0.53 ± 0.06 versus 0.60 ± 0.07 Nm/kg, respectively) and hip extension (2.68 ± 0.39 versus 2.17 ± 0.26 Nm/kg), as well as with respect to the GRFs on the inside leg while skiing (66.8 ± 7.39 versus 76.0 ± 10.0 %BW). As indicated by the JI values, there were also large asymmetries related to GRF as measured by pressure insoles (range: 42.7–56.0%). In conclusion, inter-limb asymmetries in GRFs during elite alpine skiing are not related to corresponding asymmetries in muscular strength. Although our elite athletes exhibited relatively small inter-limb asymmetries in strength, their asymmetries in GRF on-snow were relatively large.
topic biomechanics
alpine skiing
inertial suit
GNSS-global navigation satellite system
GPS-global positional system
pressure insoles
url https://www.frontiersin.org/articles/10.3389/fphys.2021.577698/full
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