The effect of a 20-week endurance training program on adipose-tissue morphology and lipolysis in men and women

In order to assess the effect of endurance training on adipose-tissue morphology and lipolysis, 22 adult subjects (11 men and 11 women) took part in a 20-week ergocycle training program, four to five days a week, 40 minutes a day, at 80% of their maximal heart rate. Before and after training, they were submitted to an adipose-tissue biopsy in the suprailiac region. Fat cell weight (FCW), and lipolytic activity were determined on isolated fat cells. For the whole sample, training significantly reduced FCW (pre: 0.40 ± 0.13 (mean ± SD) versus post: 0.36 ± 0.13 μg; P < 0.05), percentage of fat (pre: 22.0 ± 8.3 versus post: 19.7 ± 8.1%; P < 0.05), and increased adipocyte epinephrine maximal stimulated lipolysis (ESL) (pre: 1.08 ± 0.49 versus post: 1.69 ± 0.67 μmol glycerol/30 min/106 cells; P < 0.001). No changes were observed in fat cell number. In women, however, training induced no changes in the fatness indicators (% fat, sum of skinfolds, FCW). The exercise program significantly lowered the adiposity of men (% fat: P < 0.001; sum of skinfolds: P < 0.01; FCW: P < 0.05). In both sexes, a significant increase in ESL was observed after training. ESL of men, however, responded better than that of women to training (ESL of women: 1.36 ± 0.67 versus ESL of men: 2.02 ± 0.50 μmol glycerol/30 min/106 cells; P < 0.05), with increases over pre-training values of 46% and 66% in women and men, respectively. These results demonstrate that training can influence adipose-tissue morphology and lipolysis and suggest that there is a sex difference in the sensitivity to training.