The Effect of Acute and Prolonged Cooling and Heating on Muscle Force and Recovery

Background: It has been observed that temperature manipulation has different effect on skeletal muscle function. We hypothesise that both acute and prolonged heating will reduce muscle force more than cooling and recovery will be slower in the heating. Methods: Ten participants (age 27.1 ± 6.8 years) performed acute and prolonged thermal manipulations and neuromuscular testing. We measured muscle, rectal temperatures, P20, P100, and maximal voluntary isometric contraction (MVIC) after acute and prolonged cold water immersion (CWI) and hot water immersion (HWI) and control (CON) sitting. Results: Muscle temperature (Tmu) significantly increased following both acute and prolonged HWI and significantly decreased after acute and prolonged CWI, compared to baseline and CON conditions, p < 0.05. Rectal temperature (Trec) increased after HWI and declined significantly only during prolonged CWI, p < 0.05. Electrically evoked torques (P20 and P100) and MVIC decreased significantly after fatiguing stimulation across all conditions, p < 0.05, with greater post-recovery impairments in HWI compared to CWI, especially in the prolonged phase, p < 0.05. Central activation ratio (CAR) declined significantly only in the prolonged HWI condition after bath and following 3 min of recovery, compared to baseline and other conditions (p < 0.05). Conclusions: Although HWI effectively increases body temperature, it may significantly impair neuromuscular recovery more than CWI or passive rest. Keywords: cold water immersion, hot water immersion, muscle force, temperature