Relationships between walk/run performance and cardiorespiratory fitness in adolescents who are overweight

Little is known about the methods used to assess the physical fitness of adolescents who are overweight. We investigated the relationship between walk/run performance and cardiorespiratory fitness in adolescents who are overweight.

Eight African-American adolescents (5 female, 3 male) and 10 Caucasian adolescents (5 female, 5 male) who were overweight (mean age=14.5 years, SD=2.0, range=12-17; mean body mass index [BMI]=42.9 kg/m2, SD=11.5) participated in this study.

Subjects performed a 12-minute walk/run test. The distances traveled at both 9 minutes (D9) and 12 minutes (D12) were recorded, and the distance traveled between 9 and 12 minutes (D9-12) was calculated. Subjects also completed a maximal cycle ergometry test, during which peak oxygen uptake (VO2peak), anaerobic threshold (AT), peak power (Wpeak), and power at the anaerobic threshold (WAT) were determined. Body composition was determined by air displacement plethysmography.

The mean percentage of body fat was 48.6% (SD=5.3%, range=40.3%-60.4%). Percentage of body fat and BMI were each inversely related to D9, D12, and VO2peak (all P<.005). Peak oxygen uptake (r=.72, P=.0001), VO2peak/kg lean body mass (r=.60, P<.005), Wpeak (r=.88, P<.0001), and WAT (r=.72, P=.0007) were all related to D12, with greater r values than for D9. If D9-12was included in regression analyses, D9 did not account for additional variance in any of the cycle ergometry variables.

These results suggest that an easily obtained measurement of physical performance (distance traveled during a 12-minute walk/run test) is related to cardiorespiratory fitness and to body composition in adolescents who are overweight. The 12-minute walk/run distance is more predictive of cycle ergometry test results than the 9-minute distance.