Is a High Core Temperature during Exercise Associated with Greater Post-exercise Muscle Damage?

Muscle damage is a common consequence of exercise, particularly eccentric exercise. During eccentric exercise, mechanical damage to the muscle cell occurs, which leads to a variety of metabolic changes in and around the muscle cell inducing more damage. It is possible that adding heat to muscle-damaging exercise may augment the amount of damage. This research sought to answer that question. Seven young men (age 24.7 + 3.57) engaged in an eccentric exercise protocol of the elbow flexors previously proven to elicit muscle damage3, first with a thermoneutral core temperature, and two weeks later with an elevated core temperature (38.3 + 0.19°C). Max voluntary contraction (MVC), subjective muscle soreness, and creatine kinase (CK) were measured as indirect indicators of muscle damage before, and 48 hours post-exercise. No significant differences existed between trials in any of the variables measured (p \u3e 0.05). The eccentric exercise protocol failed to induce a significant elevation in CK in either trial (p \u3e 0.05). The results of this study indicate that added heat to eccentric exercise does not influence the amount of muscle damage. Furthermore, CK does not seem to be the best marker of muscle damage due to its high variability among subjects engaging in identical exercise. It is recommended that different methods of measuring muscle damage be employed in the future