CATECHOLAMINE RESPONSES TO SHORT-TERM HIGH-INTENSITY RESISTANCE EXERCISE OVERTRAINING

Seventeen weight-trained males were divided into an overtraining group [OT; n = 11; age = 22.0 +/- 0.9 (SE) yr] that weight trained their le gs daily for 2 wk with 100% 1 repetition maximum relative intensity on a squat machine and a control group (n = 6; age = 23.7 +/- 2.4 yr) th at exercised 1 day/wk with low relative intensity (50% 1 repetition ma ximum). Test batteries including strength assessments and resting and exercise-induced concentrations of epinephrine and norepinephrine were conducted at the beginning, middle, and end (tests 1-3, respectively) of the study. Strength capabilities decreased by test 3 for the OT gr oup (P < 0.05). Resting catecholamine concentrations did not change fo r either group during the study, whereas exercise-induced concentratio ns of both epinephrine (test 1 = 3,407.9 +/- 666.6 pmol/l, test 2 = 7, 563.7 +/- 1,210.6 pmol/ 1, test 3 = 6,931.6 +/- 919.3 pmol/l) and nore pinephrine (test 1 = 42.9 +/- 7.4 nmol/l, test 2 = 70.0 +/- 8.8 nmol/l , test 3 = 85.2 +/- 14.5 nmol/l) significantly increased by tests 2 an d 3 for only the OT group. Correlation coefficients suggested decrease d responsitivity of skeletal muscle to sympathetic nervous system acti vity. It appears that altered exercise-induced sympathetic nervous sys tem activity accompanies high relative intensity resistance exercise o vertraining and may be among the initial responses to the onset of the previously theoretical sympathetic overtraining syndrome.