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Reduced oxygen cost of running is related to alignment of the resultant GRF and leg axis vector: A pilot study
Author(s) -
Moore I. S.,
Jones A. M.,
Dixon S. J.
Publication year - 2016
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/sms.12514
Subject(s) - ankle , ground reaction force , kinematics , moment (physics) , physics , mathematics , chemistry , medicine , anatomy , classical mechanics
This pilot study investigated whether a 10‐week running program (10 wkRP ), which reduced the oxygen cost of running, affected resultant ground reaction force ( GRF ), leg axis alignment, joint moment characteristics, and gear ratios. Ten novice, female runners completed a 10 wkRP . Running kinematics and kinetics, in addition to oxygen consumption ( V ˙ O 2 ) during steady‐state running, were recorded pre‐ and post‐10 wkRP .V ˙ O 2decreased (8%) from pre‐10 wkRP to post‐10 wkRP . There was a better alignment of the resultant GRF and leg axis at peak propulsion post‐10wkRP compared with pre‐10 wkRP (10.8 ± 4.9 vs 1.6 ± 1.2°), as the resultant GRF vector was applied 7 ± 0.6° ( P = 0.008) more horizontally. There were shorter external ankle moment arms (24%) and smaller knee extensor moments (23%) at peak braking post‐10 wkRP . The change inV ˙ O 2was associated with the change in alignment of the resultant GRF and leg axis ( r s = 0.88, P = 0.003). As runners became more economical, they exhibited a more aligned resultant GRF vector and leg axis at peak propulsion. This appears to be a self‐optimization strategy that may improve performance. Additionally, changes to external ankle moment arms indicated beneficial low gear ratios were achieved at the time of peak braking force.