Changes in mechanical work during severe exhausting running

Abstract

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.

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

“…below OBLA). Further, the present data are of prime interest since D _ V O 2 [138 (139) m min À1 ] was comparable to, and not significantly different (P=0.33) from the D _ V O 2 [179 (93) ml min À1 ] reported by Avogadro et al (2003) for the same subjects during an exhausting run at an intensity of 90% _ V O 2max . As reported by Carter et al (2002), the amplitude of SC increases with the intensity of exercise.…”

“…As reported by Carter et al (2002), the amplitude of SC increases with the intensity of exercise. As the metabolic strain (measured as the _ V O 2 ) was 18% lower in the pulled running compared to the normal running (Avogadro et al 2003), the present D _ V O 2 should have been much lower than in normal running. As this definitely was not the case, it was thought that the metabolic strain was not the only factor involved in the increase of _ V O 2 after the third minute of exercise.…”

“…The increased _ V E explains 23-41% of SC (Candau et al 1998;Avogadro et al 2003), and recent results demonstrated that SC was not related to an increased EMG activity (Avogadro et al 2003). This latter difference is probably due to the fact that, contrary to the concentric muscle contractions encountered in cycling, running involves fast stretchshortening muscle actions (Komi 1984).…”

“…Briefly, they were: running for 829 (165) s [mean (SD)] at a velocity equal to 16.4 (1.4) km h À1 . During this session, _ V O 2 and _ V E increased respectively by 179 (93) ml min À1 and 19.7 (6.2) l min À1 from the third to the last minute of running (Avogadro et al 2003).…”

“…Treadmill velocity was adjusted within 20 s, and the subjects had to run until exhaustion. The protocol and data for this session have been reported previously (Avogadro et al 2003). Briefly, they were: running for 829 (165) s [mean (SD)] at a velocity equal to 16.4 (1.4) km h À1 .…”