AEROBIC TRAINING INDICES PRECEDE CHANGES IN VENOUS NO2-NO3 LEVELS 1041

Abstract

Animal studies demonstrated rapid adaptation of the NO synthase system following short term exercise training. We examined changes in venous NO2-NO3 and aerobic training indices during short term exercise training in sedentary humans. Maximum oxygen consumption (VO2 max) during graded treadmill exercise was measured in 16 house staff. Pre- and max-exercise bloods were obtained for NO2-NO3 measurement, following a 24 hr NO2-NO3 free diet. Eight were assigned randomly to control (C) and 8 to training (T), consisting of 4 consecutive days of treadmill exercise for 45 minutes at the respiratory anaerobic threshold. The following day all subjects were retested, after a 24 hr NO2-NO3 free diet. No difference was noted in max HR between groups for either test. VO2 max increased in T (2863 ± 228 to 3013 ± 250, ml/min) and decreased in C (3121 ± 331 to 2932± 296) (group by time effect, P=.004). VO2 at a HR of 150 increased significantly in T (126 ± 49 ml/min, p=.036) but not in C(104 ± 106, p=.36). Resting and maximum venous blood levels of NO2-NO3, measured by chemiluminescence, were unchanged in either group. (μM, mean ± s.e.m.) Table These data indicate that modest aerobic training precedes any change in venous NO2-NO3 levels.