Biomedical subjects

Patrick Avogadro

Publications and source records attributed to Patrick Avogadro.

3 recordsLinked to original sources

PubMed2004

Influence of mechanical and metabolic strain on the oxygen consumption slow component during forward pulled running.

The possible influence of increased eccentric mechanical work on the increase in oxygen uptake ( V(.)O(2)) after 3 min of running (Delta V(.)O(2)) was investigated through forward pulled running. Ten subjects ran at individually predetermined constant velocity on a treadmill, while being pulled forward. Ground reaction forces, expired gas and EMGs from leg muscles were collected after 3 min and at the end of the run. V(.)O(2) and mechanical work were then calculated. The amplitude of Delta V(.)O(2) was 138 (139) ml x min(-1) [mean (SD)]. Increased ventilation explained only 8% of Delta V(.)O(2). Stride frequency slightly decreased, inducing a similar decrease in internal work and total mechanical work (all P<0.01), while integrated EMG showed no modifications. It was concluded that Delta V(.)O(2) does not come from either an increase in mechanical work production or an increase in muscular activity. Delta V(.)O(2) could come from a lower muscle efficiency that could be due to a modification of fibre type recruitment.

Adult↗

PubMed2004

The use of treadmill ergometers for extensive calculation of external work and leg stiffness during running.

Recently, new treadmill ergometers have been designed to measure the ground reaction forces during numerous successive steps. From ground reaction forces measured in track running, it has been shown to be possible to compute external mechanical work ( W(ext)) and leg stiffness ( k) of a bouncing spring-mass system. However, to the best of our knowledge, there is still no study reporting the inter-stride coefficient of variation (CoV) of W(ext) or k parameters calculated from many successive steps. The aim of this experiment was to investigate the intra-and inter-individual variations of W(ext) and k while running at different speeds on a treadmill ergometer. Thirteen healthy runners ran at 12, 14, 16 and 18 km h(-1) during 3 min. Ground reaction forces were measured and recorded during the last 20 s of each exercise (50-62 steps). From these forces, average values and CoV of W(ext) and k were calculated. W(ext) significantly increased while k decreased with speed (both P<0.001). The mean values of these parameters were in agreement with data already reported and the CoV was less than 6% for all the parameters, showing almost no variation with speed. Therefore, this method of calculation, based on the extensive measurements of ground reaction forces, can be used to extensively study the mechanical parameters of treadmill running, and especially the inter-stride variability.

Adult↗

PubMed2003

Changes in mechanical work during severe exhausting running.

The possible contribution of muscular work to the increase in oxygen uptake ( VO(2)) over time during running was investigated on 11 adult males who were asked to run until exhaustion at 90 (3)% [mean (SD)] of their maximal aerobic velocity on a treadmill ergometer. Ground reaction forces, expired gases and EMG from leg muscles were collected for 30 s at min 3 and during the last minute of the run. Subjects ran for 829 (165) s and showed an increase in VO(2 )of 179 (93) ml.min(-1) between min 3 and exhaustion. Increased ventilation explained 41 (27)% of the increase in VO(2). Stride frequency slightly decreased but no significant differences were found in the mechanical work or in integrated EMG. It was concluded that, in running, the increase in VO(2 )could not be related to a drift in muscle work.

Adult↗