Validity and reliability of the 1/2-mile run-walk as an indicator of aerobic fitness in children with mental retardation

The purpose of this study was to determine the relationship between VO₂max and the 1/2-mile run-walk and the reliability of each in children with mental retardation (MR). Twenty-three children (13 boys, 10 girls) with mild or moderate MR participated in the study. Two maximal treadmill protocols with metabolic measurements and two 1/2-mile run-walk trials were randomly conducted on separate days. There was no difference between Trial 1 and Trial 2 for VO₂max (28.2 vs. 29.6 ml · kg^-1 · min^-1), maximal heart rate (175 vs. 177 bpm), or run-walk time (7.2 vs. 7.1 min). The test-retest correlations were r = .90 for VO₂max, r = .81 for maximal heart rate, and r = .96 for the 1/2-mile run-walk (p < .05). The correlation between VO₂max and the 1/2-mile run-walk was r = -.60 (p < .05). Adding body mass index to the model improved R to .67 (SEE = 7.3). The 1/2-mile run-walk was a reliable test, but had questionable validity as an indicator of aerobic capacity in children with mild and moderate MR.