Effect of short-term exercise training on leptin and insulin action

The purpose of the study was to determine the effect of short-term exercise training (7 consecutive days for 60 min/d at 75% maximal oxygen consumptio n [(V) over dot o(2) max]), which did not change body mass on fasting plasm a leptin concentration and insulin action. Young, lean subjects (n = 16; ag e, 21.9 +/- 0.6 years; body fat, 17.5% +/- 1.5%) and older subjects with re latively more adipose tissue (n = 14; age, 58.6 +/- 1.4 years; body fat, 28 .3% +/- 1.3%) were studied (mean +/- SE). Fasting plasma leptin was signifi cantly (P < .05) related to adiposity (fat mass, r = .58; % body fat, r = . 76) in this population. Body mass did not change (P < .05) in any of the gr oups with training (71.8 +/- 2.5 v 71.9 +/- 2.5 kg). The insulin sensitivit y index (S-1 determined from an intravenous glucose tolerance test (IVGTT) improved significantly (P < .05) in both the young group (4.8 +/- 0.6 v 6.9 +/- 0.8 x 10(-4)/ min (mu U/mL) and the older group (3.2 +/- 0.6 v 5.9 +/- 1.0 x 10(-4)/min (mu U/mL)). Fasting leptin did not change with training i n either group (10.4 +/- 1.6 v 9.2 +/- 1.0 ng/mL). These findings suggest t hat exercise does not independently affect the fasting plasma leptin concen tration and the improvement in insulin action with exercise is not associat ed with an alteration in fasting leptin in healthy sedentary lean and relat ively lean subjects. Copyright in 2000 by W.B. Saunders Company.