Abstract
Eighteen male marathon runners (mean marathon performance: 2 h 36 min, SD = 7.0 min;
V̇O2max = 64.1 ± 15.1 ml/kg·min-1) were submitted to a needle biopsy in the suprailiac region and to various measurements
of body fatness: percent body fat (% fat), seven skinfold thicknesses, and mean fat
cell diameter. Basal and insulin-stimulated glucose conversion into triglycerides
were measured in collagenase-isolated fat cells, while heparin-releasable lipoprotein
lipase activity (LPLa) was determined in intact adipose tissue. All body fatness indicators
were significantly smaller in marathon runners in comparison to a sedentary control
group (P < 0.001). Fat cell basal and insulin-stimulated glucose conversion into triglycerides
as well as LP La were significantly higher for the runners group (P < 0.01), differences being particularly important when comparisons were performed
between subjects paired for mean fat cell diameter. Pearson interclass correlations
between body fatness and fat cell glucose incorporation into triglycerides were low
and positive for the sedentary group (0.04 ≦ r ≦ 0.41), while they were negative for the marathon runners groups (-0.28 ≦ r ≦ -0.40) with the exception of% fat. Moreover, correlations between LPLa and indicators
of body fatness were positive in the sedentary group (0.47 ≦ r ≦ 0.79), while they were negative in the marathon runners group (-0.03 ≦ r ≦ -0.63). These results indicate that long-distance runners are characterized by
increased adipose tissue lipid accumulation activities, possibly as a result of their
endurance training regimen.
Key words
adipose tissue - endurance training - lipogenesis - lipoprotein lipase - fat cell
