The purpose of this study was to determine how different training modes would influence blood levels of growth hormone (hGH) and selected physiological parameters. Three training groups were established: LIFT, in which subjects trained with free weights and a Universal Gym three times per week with three sets at six to eight repetitions per lift (75 percent of one-repetition maximum) for 10 weeks; RUN, in which subjects ran at 75 percent of HR max three times per week; and COMBO, in which subjects underwent both LIFT and RUN training. Resting hGH levels were determined before and after training, and the hGH response to a single bout of exercise was determined at one, four, eight and 10 weeks. Each subject was tested for one-repetition (1 RM) strength in the bench and leg press during weeks one and 10 of training. Resting and exercise response blood samples were taken from an anticubital vein and centrifuged, and the serum was analyzed for hGH by radioimmunoassay techniques. The results of the hormonal measurements indicate that except for a significant (p < 0.05) decrease in the resting levels of hGH in the LIFT group, training did not alter hGH levels at rest. The 10 weeks of exercise training did not change the basic hGH response to a single bout of exercise in the LIFT and COMBO groups, but did shift the hGH peak of RUN subjects from four to eight minutes by the eighth week of training. The non-hormonal factors affected were: [latin capital V with dot above]O2 max of RUN and COMBO was significantly higher (p < 0.05) above LIFT; LBM and upper body strength of LIFT and COMBO was significantly elevated (p < 0.05) than RUN; and significant gains (p < 0.05) in lower body strength occurred only in LIFT, The data indicate that 10 weeks of exercise training does not significantly alter the basic hGH response to a single bout of exercise, but can influence the appearance of the hormonal peak. The results also show that a training program involving both running and lifting can produce the same gains in [latin capital V with dot above]O2 max and upper body strength as single-activity programs, but does not produce lower body strength gains.
(C) 1991 National Strength and Conditioning Association