Changes in mechanical work during severe exhausting running

The possible contribution of muscular work to the increase in oxygen uptake ((V) over dot O-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 (V) over dot O-2 of 179 (93) ml.min(-1) between min 3 and exhaustion. Increased ventilation explained 41 (27)% of the increase in (V) over dot O-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 (V) over dot O-2 could not be related to a drift in muscle work.