Endurance training amplifies the pulsatile release of growth hormone: effects of training intensity.
The effects of intensity of run training on the pulsatile release of growth hormone (GH) were investigated in 21 eumenorrheic untrained women. The O2 consumption (VO2) at the lactate threshold (LT); fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM; peak VO2; maximal VO2; body composition; and pulsatile release of GH were measured. Subjects in both the at-lactate threshold (/LT, n = 9) and above-lactate threshold (greater than LT, n = 7) training groups increased VO2 at LT and FBLC of 2.0, 2.5, and 4.0 mM and VO2max after 1 yr of run training. However, the increase observed in the greater than LT group was greater than that in the /LT group (P less than 0.05). No change was observed for the control group (n = 5). No among- or within-group differences were observed for body weight, although trends for reductions in percent body fat (P less than 0.06) and fat weight (P less than 0.15) were observed in the greater than LT group, and both training groups significantly increased fat-free weight (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Weltman
A
A
Exercise Physiology Laboratory, Curry School of Education, University of Virginia, Charlottesville 22903.
Weltman
J Y
JY
Schurrer
R
R
Evans
W S
WS
Veldhuis
J D
JD
Rogol
A D
AD
D000293:Adolescent; D000328:Adult; D001823:Body Composition; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D010101:Oxygen Consumption; D010806:Physical Education and Training; D010807:Physical Endurance / Q000502:physiology*; D013997:Time Factors
D007773:Lactates; D019344:Lactic Acid; D013006:Growth Hormone