Mechanical Alterations to Repeated Treadmill Sprints in Normobaric Hypoxia.

Détails

ID Serval
serval:BIB_803F43A8C95B
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Mechanical Alterations to Repeated Treadmill Sprints in Normobaric Hypoxia.
Périodique
Medicine and Science in Sports and Exercise
Auteur(s)
Brocherie F., Millet G.P., Morin J.B., Girard O.
ISSN
1530-0315 (Electronic)
ISSN-L
0195-9131
Statut éditorial
Publié
Date de publication
2016
Peer-reviewed
Oui
Volume
48
Numéro
8
Pages
1570-1579
Langue
anglais
Notes
Publication types: Journal Article Publication Status: ppublish
Résumé
PURPOSE: Compelling evidence suggests larger performance decrements during hypoxic versus normoxic repeated sprinting. Yet the underlying mechanical alterations have not been thoroughly investigated. Therefore, we examined the effects of different levels of normobaric hypoxia on running mechanical performance during repeated treadmill sprinting.
METHODS: Thirteen team sport athletes performed eight 5-s sprints with 25 s of passive recovery on an instrumented treadmill in either normoxia near sea level (SL; FiO2 = 20.9%), moderate normobaric hypoxia (MH; FiO2 = 16.8%; corresponding to ~1800 m altitude), or severe normobaric hypoxia (SH; FiO2 = 13.3%; ~3600 m).
RESULTS: Net power output in the horizontal direction did not differ (P > 0.05) between conditions for the first sprint (mean ± SD, pooled values: 13.09 ± 1.97 W·kg) but was lower for the eight sprints in SH compared with SL (-7.3% ± 5.5%, P < 0.001) and MH (-7.1% ± 5.9%, P < 0.01), with no difference between SL and MH (+0.1% ± 8.0%, P = 1.00). Sprint decrement score was similar between conditions (pooled values: -11.4% ± 7.9%, P = 0.49). Mean vertical, horizontal, and resultant ground reaction forces decreased (P < 0.001) from the first to the last repetition in all conditions (pooled values: -2.4% ± 1.9%, -8.6% ± 6.5%, and -2.4% ± 1.9%). This was further accompanied by larger kinematic (mainly contact time: +4.0% ± 2.9%, P < 0.001, and +3.3% ± 3.6%, P < 0.05, respectively; stride frequency: -2.3% ± 2.0%, P < 0.01, and -2.3% ± 2.8%, P < 0.05, respectively) and spring-mass characteristics (mainly vertical stiffness: -6.0% ± 3.9% and -5.1% ± 5.7%, respectively, P < 0.01) fatigue-induced changes in SH compared with SL and MH.
CONCLUSION: In SH, impairments in repeated sprint ability and in associated kinetics/kinematics and spring-mass characteristics exceed those observed near SL and in MH (i.e., no or minimal difference). Specifically, SH accentuates the repeated sprint ability fatigue-related inability to effectively apply forward-oriented ground reaction force and to maintain vertical stiffness and stride frequency.
Pubmed
Web of science
Création de la notice
14/04/2016 17:46
Dernière modification de la notice
20/08/2019 15:40
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