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 legs 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) that exercised 1 day/wk with low relative intensity (50% 1 repetition maximum). 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 group (P < 0.05). Resting catecholamine concentrations did not change for either group during the study, whereas exercise-induced concentrations of both epinephrine (test 1 = 3,407.9 +/- 666.6 pmol/l, test 2 = 7,563.7 +/- 1,210.6 pmol/l, test 3 = 6,931.6 +/- 919.3 pmol/l) and norepinephrine (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 and 3 for only the OT group. Correlation coefficients suggested decreased responsitivity of skeletal muscle to sympathetic nervous system activity. It appears that altered exercise-induced sympathetic nervous system activity accompanies high relative intensity resistance exercise overtraining and may be among the initial responses to the onset of the previously theoretical sympathetic overtraining syndrome.
Fry
A C
AC
Center for Sports Medicine, Pennsylvania State University, University Park 16802.
Kraemer
W J
WJ
Van Borselen
F
F
Lynch
J M
JM
Triplett
N T
NT
Koziris
L P
LP
Fleck
S J
SJ
D000328:Adult; D002395:Catecholamines / Q000097:blood*; D004837:Epinephrine / Q000097:blood; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D009638:Norepinephrine / Q000097:blood; D010806:Physical Education and Training
D002395:Catecholamines; D009638:Norepinephrine; D004837:Epinephrine