Downhill running increases markers of muscle damage and impairs the maximal voluntary force production as well as the late phase of the rate of voluntary force development.

Abstract

To examined the time-course of the early and late phase of the rate of voluntary force development (RVFD) and muscle damage markers after downhill running. Ten recreational runners performed a 30-min downhill run at 10kmh-1 and -20% (-11.3°) on a motorized treadmill. At baseline and each day up to 4days RVFD, knee extensors maximum voluntary isometric force (MVIC), serum creatine kinase (CK) concentration, quadriceps swelling, and soreness were assessed. The early (0-50ms) and late (100-200ms) phase of the RVFD, as well as the force developed at 50 and 200ms, were also determined. MVIC showed moderate decrements (p < 0.05) and recovered after 4days (p > 0.05). Force at 50ms and the early phase were not impaired (p > 0.05). Conversely, force at 200ms and the late phase showed moderate decrements (p < 0.05) and recovered after 3 and 4days, respectively (p > 0.05). CK concentration, quadriceps swelling, and soreness increased (p < 0.05) were overall fully resolved after 4days (p > 0.05). Downhill running affected the knee extensors RVFD late but not early phase. The RVFD late phase may be used as an additional marker of muscle damage in trail running.