Resistance training performed under a partial range of motion elicits favorable hormonal responses in untrained young men

PURPOSE: This study aimed to examine the acute effects of full range of motion (FROM) versus partial range of motion (PROM) resistance training on metabolic and hormonal responses in untrained men. METHODS: Ten untrained men (24.1 ± 1.2 yrs) performed three sets of back squat and bench press exercises at their 10-repetiton maximum under three conditions separated by one week: (1) FROM movement; (2) PROM movement; and (3) passive rest (CON). Blood samples were collected before, immediately post-exercise, and 15 min post-exercise, and blood lactate, serum levels of growth hormone, total testosterone, and cortisol were analyzed. RESULTS: Blood lactate was significantly increased immediately after both FROM and PROM training and this level was significantly greater under FROM training than under PROM training (11.97 ± 1.96 vs. 9.37 ± 2.18 mmol/L; p < 0.05). Total testosterone was significantly increased immediately after both FROM and PROM training. While this level had returned to its baseline level at 15 min after FROM training, it remained significantly higher after PROM training. Growth hormone was significantly higher than the baseline level at 15 min after both FROM and PROM training, but the difference was not significant. Cortisol was significantly higher than the baseline level at 15 min only after FROM training, and it was significantly higher than CON condition (17.94 ± 4.55 vs. 11.94 ± 5.90 ng/mL; p < 0.05). CONCLUSION: These results indicate that initiating sessions with PROM resistance training (top half of a lift) may optimize hormonal responses in untrained young men.