Pedal Rate Influence on Oxygen Consumption in Eccentric

Overview

Nowadays, ECC exercise can be realized using various modalities that target small or large muscle masses in a segmentary or dynamic way. The training program proposed in this study is realised on an handmade ergocycle which allows eccentric contractions. With this type of ergometer, O2 consumption (VO2) is three to five fold lower than during an exercise realised at the same power output with a concentric ergocycle. Due to this later propertie, which origins are not yet fully identified, there is an increasing interest to embed ECC in rehabilitation programs. The investigators hypothesis that a higher pedal rate will induce a lower oxygen consumption, with the same benefits. This study aims to compare oxygen consumption at two pedal rates : 50 and 80 rotation per minute (rpm). The ultimate goal is to assess efficacy and tolerance of eccentric training on ergocycle and to enhance comprehension of the physiological mecanisms involved in the lower O2 consumption observed.

The training program proposed in this study is realised on an handmade ergocycle which allows almost pur eccentric contractions. Fifteen healthy volunteers realize a incremental test until exertion on a concentric ergometer. If the minimal power output of 200W is reached, the volunteers are familiarized with eccentric exercise during several bouts of exercise. This habituation session allows avoiding the secondary muscular effects of high intensity eccentric exercise. Then, volunteers could take part in a two-stepped eccentric protocol: 1) an incremental test consisting in 3 stages. Each stage lasts 4 minutes. 2\) A constant-load test realized at 320W during 6 minutes. Each test is realized twice: at 50 and 80 rpm and sequence is randomly assigned. \[One step (incremental or constant load) = two tests (50 and 80 rpm)\] During each step, oxygen consumption is continuously measured, as well as cardiac output and muscular activity and intramuscular oxygen kinetic.