RELATIONSHIP BETWEEN PEAK ??Vo2 AND RECOVERY ??Vo2 KINETICS IN HIGH SCHOOL AGE GIRLS 708

Abstract

Both peak ˙Vo2 and the kinetics of ˙Vo2 during submaximal exercise have been used as indices of cardiorespiratory fitness. Further, these variables are inversely related when healthy subjects and CHF patients are compared together (Cohen-Solal et al, Circ. 91:2924, 1995). Determining these variables requires two different exercise tests--incremental and constant work rate. We wondered if the kinetics of ˙Vo2 in recovery from incremental, maximal exercise would demonstrate a similar inverse relationship to peak ˙Vo2. We examined these relationships in 19 high school girls (age 15-17). Each girl performed an incremental (ramp) test to volitional fatigue on an upright cycle ergometer. ˙Vo2 was determined breath-by-breath during exercise and for 6 min of recovery.˙Vo2 kinetics were determined by fitting the recovery response following the ramp test to a three exponential decay function. A mean response time (MRT) was calculated as the sum of the amplitude-weighted (time constant+ time delay) for each exponential term. Peak ˙Vo2 averaged 1.30±0.56 L/min (22.7±7.9 ml/min/kg), while MRT was 51.9±23.4 sec. The MRT is significantly faster than that found by Cohen-Solal for middle-aged healthy men (80±11 sec, P<0.001). Peak˙Vo2 (L/min) was significantly correlated with body weight(r=0.60,P<0.005), while MRT was weakly related (r=0.44, P<0.05). In contrast to our hypothesis, there was no significant correlation between MRT and peak ˙Vo2 (as ml/kg/min)(r=0.20). In conclusion, MRT following maximal exercise is sensitive to age, body mass and possibly gender. However, MRT does not relate to peak ˙Vo2 in healthy post-pubertal girls.