Plasma protein carbonyl response to increasing exercise duration in aerobically trained men and women.

The purpose of this study was to determine the effect of aerobic exercise duration on plasma protein carbonyl concentrations, a marker of protein oxidation, in aerobically trained men and women. Eight men (age: 27 +/- 4 years, VO (2peak): 4.09 +/- 0.26 L x min (-1); mean +/- SD) and 7 women (age: 27 +/- 6 years, VO (2peak): 2.33 +/- 0.24 L x min (-1)) exercised on an electrically-braked cycle ergometer at 70 % VO (2peak) for 30, 60 or 120 minutes on three separate days. Plasma samples collected before and immediately, 30- and 60-minutes post-exercise were analyzed for protein carbonyls. Mean oxygen uptake was greater for men in all conditions (2.75 +/- 0.03 L x min (-1); 38 +/- 0.43 ml x kg (-1) x min (-1)) compared to women (1.57 +/- 0.03 L x min (-1); 24.1 +/- 0.47 ml x kg (-1) x min (-1)). Total work performed during the exercise sessions was also greater for men than for women during the 30 (368 +/- 11 versus 223 +/- 7 kJ), 60 (697 +/- 17 versus 423 +/- 18 kJ), and 120-minute conditions (1173 +/- 44 versus 726 +/- 28 kJ) (Mean +/- SEM). Although these comparisons were significant (p < 0.0001), sex differences in total work performed and mean VO (2) did not result in sex differences in protein carbonyls. However, a condition by time interaction was observed with greater post-exercise values following the 120-minute condition compared to both the 30- and 60-minute conditions. Protein carbonyl concentration was greatest immediately post-exercise for both men and women and generally declined in a linear trend through one hour of recovery. These data suggest that protein carbonyl concentration is elevated by cycling exercise performed at 70 % VO (2peak), is greater following longer duration rides, begins to recover within one hour following exercise, and is not different between men and women.