Heat pre-conditioning may induce increased heat-shock protein expression, which may, in turn, protect the muscle fibers from being damaged during subsequent eccentric contraction (ECC) exercises. This study investigated the effect of heat treatment applied before each repeated-ECC program on muscle damage and soreness. Thirteen untrained male (21±1yr) volunteers participated in this study and were assigned randomly to either the control (CON, n=7) or heat (HEAT, n=6) group. One day before the first ECC, microwave hyperthermia treatment (150W, 20min) was administered to the training arm in the HEAT group. The ECC consisted of 30 repetitions of maximum isokinetic eccentric contractions (10reps×3sets, twice/wk for 2wks) of the elbow flexors at 30ﾟs⁻¹ using an isokinetic dynamometer. The maximum isometric strength, range of motion (ROM) of the elbow joint, upper arm circumference, blood creatine kinase activity, and muscle soreness were assessed before and after each ECC. The HEAT group had a significantly greater ROM than the CON group before and after the third ECC. None of the other variables differed between the CON and HEAT groups. These results suggest that heat treatment of skeletal muscles one day before ECC results in a slightly attenuated decrease in ROM during ECC training interrention.

DESCENTE SPORTS SCIENCE Vol.33/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE