Affiliation:
1. Laboratoire de Physiologie--Groupement d'Interet Public Exercise, Lyon-Sud, France.
Abstract
This investigation examined, in a group of 10 trained male runners, the effect of vertical loading during level treadmill running at a velocity of 5 m/s. The net energy cost of running (Cr), the external work of the center of mass of the body (Wext; both expressed in J.kg-1.m-1), and the eccentric-to-concentric ratio (Ecc/Con) of integrated electromyographic activity for the vastus lateralis (VL) and gastrocnemius lateralis muscles were measured. It was observed that Wext and Ecc/Con for the VL could explain a large part of the interindividual variations in Cr. This result reinforces the hypothesis that Ecc/Con could be a good index of effectiveness in the stretch-shortening cycle. When the subjects ran with a vertical load of 9.3% of their body mass, Cr and Wext were significantly reduced (P < 0.01 and P < 0.05, respectively), whereas Ecc/Con for the VL and gastrocnemius lateralis remained unchanged. The variations in Cr and Wext due to vertical loading were significantly correlated (r = 0.75; P < 0.01). It was then concluded that the significant improvement of Cr observed with the added load was mainly due to the fact that Wext was significantly decreased.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
37 articles.
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