Mechanical Determinants of the U-Shaped Speed-Energy Cost of Running Relationship.

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Serval ID
serval:BIB_FFB141E83278
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Mechanical Determinants of the U-Shaped Speed-Energy Cost of Running Relationship.
Journal
Frontiers in physiology
Author(s)
Carrard A., Fontana E., Malatesta D.
ISSN
1664-042X (Print)
ISSN-L
1664-042X
Publication state
Published
Issued date
2018
Peer-reviewed
Oui
Volume
9
Pages
1790
Language
english
Notes
Publication types: Journal Article
Publication Status: epublish
Abstract
Purpose: The aim of this study was to investigate the relationship between the energy cost of running (Cr) and speed and its mechanical determinants by comparing running in normal [100% body weight (BW)] and reduced (20% and 60% BW) gravity conditions at several speeds (2.25, 3.17, 4.08, and 5.00 m·s <sup>-1</sup> ) in experienced runners. Methods: Twelve experienced runners (24.6 ± 5.4 year) ran on an AlterG treadmill in a partially randomized order at the four running speeds and at the three gravity conditions in order to assess Cr, spatiotemporal parameters, spring-mass characteristics and elastic energy (EL) during running. Results: For the three gravity conditions, the speed-Cr per kg of body mass relationship was curvilinear (significant speed effect: P < 0.001) and was significantly downward shifted with reduced gravity (100%>60%>20% BW; P < 0.001). EL, expressed in J·step <sup>-1</sup> , was significantly higher at 100% BW than at 60 and 20% BW and at 60% BW than at 20% BW (significant gravity effect: P < 0.001) with a significant increase in EL per step at faster speeds for the 3 gravity conditions (P < 0.001). EL, expressed in J·kg <sup>-1</sup> ·m <sup>-1</sup> , was significantly downward shifted with gravity (100%>60%>20% BW; P < 0.001), with no significant speed effect (P = 0.39). Conclusions: Our findings showed that, for the three gravity conditions, the speed-Cr relationship was curvilinear, and the optimization of the stretch-shortening cycle and muscle activation in the muscle-tendon unit may be involved to explain these U-shaped relationships, especially at normal terrestrial gravitational conditions (100% BW). The U-shaped speed-Cr per kg of the body mass relationship was shifted downward in hypogravity conditions, which was characterized by decreased EL compared to 100% BW. These mechanisms may contribute to the less than proportional decrease in Cr per kg of body mass relative to gravity.
Keywords
Physiology (medical), Physiology, biomechanics, elastic energy, hypogravity, optimal speed, stretch-shortening cycle
Pubmed
Web of science
Open Access
Yes
Create date
18/12/2018 14:59
Last modification date
21/08/2019 6:11
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