According to adolescent and parent reports, overweight is associated with poorer QOL in adolescence, regardless of race; however, compared with overweight white adolescents, blacks report less impairment in QOL. Future research is required to determine whether differences in QOL are predictive of treatment success.

ABSTRACT. Objective. Relatively little is known about how excess body mass affects adolescents' capacity to perform sustained exercise. We hypothesized that most of the difficulty that severely overweight adolescents have with sustained exercise occurs because the metabolic costs of moving excess mass result in use of a high proportion of their total oxygen reserve.Methods. We compared results from a maximal cycle ergometry fitness test in 129 severely overweight adolescents who had BMIs of 41.5 ؎ 9.7 kg/m 2 and ages of 14.5 ؎ 1.8 years (range: 12.1-17.8 years) and 34 nonoverweight adolescents who had BMIs of 20.1 ؎ 2.9 kg/m 2 and ages of 14.5 ؎ 1.5 years (range: 12.0 -18.1 years). Oxygen uptake (V O 2 ) was compared at 3 times: during a 4-minute period of unloaded cycling (ULV O 2 ), at the lactate threshold estimated by gas exchange (LTV O 2 ), and at maximal exertion (V O 2 max). Heart rate was obtained at rest and at V O 2 max. Participants also completed a 12-minute walk/ run performance test to obtain distance traveled (D12) and heart rate. Results. Absolute LTV O 2 and V O 2 max and LTV O 2 as a percentage of V O 2 max were not different in overweight and nonoverweight adolescents during the cycle test.However, absolute ULV O 2 was significantly greater in overweight adolescents: ULV O 2 accounted for 35 ؎ 8% of V O 2 max (and 63 ؎ 15% of LTV O 2 ) in overweight adolescents but only 20 ؎ 5% of V O 2 max (and 39 ؎ 12% of LTV O 2 ) in nonoverweight adolescents. Resting heart rate before initiating the cycle test was significantly greater in overweight than nonoverweight adolescents (94 ؎ 14 vs 82 ؎ 15 beats per minute). However, maximal heart rate during the cycle test was significantly lower in overweight adolescents (186 ؎ 13 vs 196 ؎ 11 beats per minute). During the walk/run test, mean D12 was significantly shorter for overweight than for nonoverweight adolescents (1983 ؎ 323 vs 1159 ؎ 194 m). D12 was negatively related to BMI SDS (r ‫؍‬ ؊0.81) and to ULV O 2 (r ‫؍‬ ؊0.98).Discussion. Overweight and nonoverweight adolescents had similar absolute V O 2 at the lactate threshold and at maximal exertion, suggesting that overweight adolescents are more limited by the increased cardiorespiratory effort required to move their larger body mass through space than by cardiorespiratory deconditioning. ABBREVIATIONS. V o 2 max, maximum oxygen uptake; SDS, SD score; ULV o 2 , unloaded oxygen uptake; LTV o 2 , oxygen uptake at the lactate threshold; V o 2 max, oxygen uptake at maximal exertion; HRR, heart rate reserve; RPE, rating of perceived exertion; bpm, beats per minute; D12, distance achieved at 12 minutes during walk/run test; ANCOVA, analysis of covariance. O verweight during childhood has been identified as a major health problem in the United States. 1-4 Pediatric overweight commonly presages adult obesity 5 and is associated with the development of weight-related comorbid conditions and increased morbidity. [6][7][8] Decreased physical activity and a more sedentary lifestyle have been implicated as importan...