THE EFFECTS OF SHORT-TERM RESISTANCE TRAINING ON ENDOCRINE FUNCTION IN MEN AND WOMEN

This investigation examined hormonal adaptations to acute resistance e xercise and determined whether training adaptations are observed withi n an 8-week period in untrained men and women. The protocol consisted of a 1-week pre-conditioning orientation phase followed by 8 weeks of heavy resistance training. Three lower-limb exercises for the quadrice ps femoris muscle group (squat, leg press, knee extension) were perfor med twice a week (Monday and Friday) with every other Wednesday used f or maximal dynamic 1 RM strength testing. Blood samples were obtained pre-exercise (Pre-Ex), immediately post-exercise (IP), and 5 min post- exercise (5-P) during the first week of training (T-1), after 6 weeks (T-2) and 8 weeks (T-3) of training to determine blood concentrations of whole-blood lactate (LAC), serum total testosterone (TT), sex-hormo ne binding globulin (SHBG), cortisol (CORT) and growth hormone (GH). S erum TT concentrations were significantly (P less than or equal to 0.0 5) higher for men at all time points measured. Men did not demonstrate an increase due to exercise until T-2. An increase in pre-exercise co ncentrations of TT were observed both for men and women at T-2 and T-3 . No differences were observed for CORT between men and women; increas es in CORT above pre-exercise values were observed for men at all trai ning phases and at T-2 and T-3 for women. A reduction in CORT concentr ations at rest was observed both in men and women at T-3. Women demons trated higher pre-exercise GH values than men at all training phases; no changes with training were observed for GH concentrations. Exercise -induced increases in GH above pre-exercise values were observed at al l phases of training. Women demonstrated higher serum concentrations o f SHBG at all time points. No exercise-induced increases were observed in men over the training period but women increased SHBG with exercis e at T-3. SHBG concentrations in women were also significantly higher at T-2 and T-3 when compared to T-1 values. Increases in LAC concentra tions due to exercise were observed both for men and women for all tra ining phases but no significant differences were observed with trainin g. These data illustrate that untrained individuals may exhibit. early -phase endocrine adaptations during a resistance training program. The se hormonal adaptations may influence and help to mediate other adapta tions in the nervous system and muscle fibers, which have been shown t o be very responsive in the early phase of strength adaptations with r esistance training.