BLOOD LACTATE AND PERCEIVED EXERTION RELATIVE TO VENTILATORY THRESHOLD - BOYS VERSUS MEN

The purpose of this study was to examine blood lactate (BLa) levels an d ratings of perceived exertion (RPE) in nine boys (10.5 +/- 0.7 yr) a nd nine men (25.3 +/- 2.0 yr) during exercise relative to ventilatory threshold (VT). VT and VO2max were determined during a graded exercise test on a cycle ergometer. On three additional days each subject exer cised for 10 min at either 80, 100, or 120% of the (V) over dot O-2 at VT. Capillary BLa levels and RPE were assessed at minutes 5 and 10 of each trial. (V) over dot O-2max averaged 47.7 +/- 5.4 and 50.2 +/- 6. 2 mL.g.(-1)min(-1) in the boys and men, respectively (P > 0.05). VT ex pressed as %(V) over dot O-2max was 67.2 +/- 3.5% in the boys and 67.3 +/- 4.9% in the men (P > 0.05). BLa levels ranged from 2.0 +/- 0.7 to 4.7 +/- 0.9 mmol.L-1 in the boys and from 2.6 +/- 0.5 to 8.2 +/- 2.1 mmol.L-1 in the men across the three intensities. Corresponding RPE va lues ranged from 11.2 +/- 1.8 to 16.2 +/- 2.2 in the boys and from 10. 2 +/- 1.2 to 15.8 +/- 1.7 in the men. A group X time X intensity inter action (P < 0.05) indicated that BLa in the men increased more so acro ss time and intensity. There were no significant group difference or i nteractions involving RPE during exercise. Setting exercise intensity relative to VT did not abolish child-adult differences with respect to submaximal BLa levels. Despite maintaining lower BLa levels. RPE valu es were similar between boys and men.