G. Pyka et al., EFFECT OF A SUSTAINED PROGRAM OF RESISTANCE TRAINING ON THE ACUTE GROWTH-HORMONE RESPONSE TO RESISTANCE EXERCISE IN OLDER ADULTS, Hormone and Metabolic Research, 26(7), 1994, pp. 330-333
We have previously shown that an episode of resistance exercise provok
es an acute rise in circulating growth hormone (GH), and that this ris
e is severely blunted in older men and women. To determine whether thi
s impairment simply reflects the decreased physical fitness of older p
eople, we studied the effects of long-term resistance training on circ
ulating levels of GH and insulin-like growth factor I (IGF-I) and on t
he acute GH response to exercise in 5 men and 9 women, aged 69.6 +/- 1
.1 yrs (SEM). Subjects were randomly assigned to either an exercise pr
ogram, consisting of 12 weight-lifting exercises (3 sets of 8 repetiti
ons, 3 times each week) or to a control group. After testing maximum b
aseline strength by the 1 RM method subjects returned to the laborator
y for assessment of basal GH and IGF-I levels and the GH response to e
xercise. Venous blood was drawn at baseline, after each of 12 exercise
s (3 sets of 8 repetitions at 85% 1 RM), and every 2 minutes into the
first 10 minutes of recovery. The exercise circuit with blood sampling
was repeated at 15, 30 and 52 weeks for both groups. Basal GH and IGF
-I values did not change in either group throughout the training perio
d nor did the GH secretory response to exercise. Three exercisers had
a peak GH concentration greater than 8 mu g/l after 30 weeks of traini
ng, although only one of these showed a significant increase (29 mu g/
l) after 52 weeks. We conclude that a sustained program of moderate in
tensity resistance training does not repair age-related deficits in ci
rculating levels of growth hormone or IGF-I, either at rest or followi
ng an acute exercise stimulus.