Muscle temperature influences oxygen uptake and blood flow during single leg isokinetic exercise.

Abstract

Thermal changes in muscle tissues (i.e: cooling and heating) modulate local oxygen transport from the muscle and into the cell. Whether a change in skeletal muscle oxygen transport subsequently regulate oxygen consumption (V̇ O2m) and tissue oxygenation (%TSI) during exercise is unclear. The purpose of this study was to assess the effects of skeletal muscle cooling and heating on muscle blood flow (Q̇ mus), V̇ O2m, and %TSI during single-leg isokinetic exercise. Eleven men exercised during 3-min intervals under thermoneutral (TN) condition, and localized muscle heating (HT) and cooling (CO), at 10%, 30%, and 50% of their maximal voluntary contraction (MVC). An occlusion technique combined to near-infrared spectroscopy was used to estimate V̇ O2m and Q̇ mus before and after exercise bouts. The results of this study showed that Q̇ mus was significantly increased in HT, while V̇ O2m was instead decreased in CO. Muscle temperature did not significantly change %TSI during exercise. Moreover, the relationship between Q̇ mus and V̇ O2m (TN: 0.173  0.101, CO: 0.187  0.0655, and HT:0.107  0.0413) was steeper in CO compared to HT (p = 0.009). In conclusion, this study demonstrated that muscle temperature regulates the blood flow/O2 consumption relationship during incremental isokinetic exercise.