This pilot project compared the hGH release patterns of the back squat to the leg press following 3 workloads to determine whether lifting mechanics could influence hormonal output. Subjects, 3 experienced male weight lifters (25.3 +/- 0.3 yrs), performed 3 back squat and 3 leg press trials using repetition workloads of 3-, 10-, and 25-RM. Blood samples (3 ml) taken preexercise and at 4, 8, and 16 min postexercise were analyzed for hGH and lactic acid. The hGH response indicates that the 10-RM workload gave the greatest significant hGH output (1.67 [micro]g/L above baseline by 4 min) of the 3 leg press trials, whereas the 25-RM workload of the back squat (1.25 [micro]g/L above pre by 4 min) was the most effective in that lift. Only the 10- and 25-RM workloads produced a significant increase in lactic acid in the back squat or leg press trials. The results indicate that the hGH response to these exercises is not the same, probably due to the mechanics of the lift.
(C) 1996 National Strength and Conditioning Association