COMPATIBILITY OF HIGH-INTENSITY STRENGTH AND ENDURANCE TRAINING ON HORMONAL AND SKELETAL-MUSCLE ADAPTATIONS

Thirty-five healthy men were matched and randomly assigned to one of f our training groups that performed high-intensity strength and enduran ce training (C; n = 9), upper body only high-intensity strength and en durance training (UC; n = 9), high-intensity endurance training (E; n = 8), or high-intensity strength training (ST; n = 9). The C and ST gr oups significantly increased one-repetition maximum strength for all e xercises (P < 0.05). Only the C, UC, and E groups demonstrated signifi cant increases in treadmill maximal oxygen consumption. The ST group s howed significant increases in power output. Hormonal responses to tre admill exercise demonstrated a differential response to the different training programs, indicating that the underlying physiological milieu differed with the training program. Significant changes in muscle fib er areas were as follows: types I, IIa, and IIc increased in the ST gr oup; types I and IIc decreased in the E group; type IIa increased in t he C group; and there were no changes in the UC group. Significant shi fts in percentage from type IIb to type IIa were observed in all train ing groups, with the greatest shift in the groups in which resistance trained the thigh musculature. This investigation indicates that the c ombination of strength and endurance training results in an attenuatio n of the performance improvements and physiological adaptations typica l of single-mode training.