Objectives.—The aim of this study was to investigate the effect of changing concentric- eccentric contraction time ratio in a single session of resistance exercise on hormonal response in trained men. Methods. — In a double-blind cross section study design, ten young men (mean age: 26.3 ± 1.2 years, mean weight: 81.2 ± 4.25 kg, and mean height: 178 ± 6 cm) were selected and completed 4 resistance exercise sessions with 3 days’ between sessions interval. Protocols included, 1 sec- ond concentric and 1 second eccentric contraction; 3 second concentric and 3 second eccentric contraction; 4 second concentric and 2 seconds eccentric contraction; 2 seconds concentric and 4 seconds eccentric contraction. In each session subjects performed one of the four protocols. The exercise protocol was consisted of leg extension, bench press, hamstring curls and lat pull- down with three sets of eight repetitions and intensity of 0.65 of one repetition maximum. Rest times for sets and exercises were 1 and 2 minutes respectively. Blood samples were collected before and immediately after exercise.Results. — Increases in lactate were observed after all protocols. Serum levels of testosterone and growth hormone increased significantly in all, but 1 second concentric and 1 second eccen- tric contraction protocol, while level of serum cortisol did not change significantly in none of the protocols. Conclusions.—The result of this study showed that in a single session of RE, changes in concentric-eccentric contraction time ratio had no effect on hormonal response, however slower contractions produced greater hormonal response compare to normal protocol.
