Characteristics associated with running performance in young boys.

The purpose of the study was to replicate and extend the investigation of characteristics associated with running performance in young boys. Two groups of 10-year-old males were studied. One group (A runners) consisted of subjects who placed above the 55th percentile on a 1.6-km run; a second group (B runners) included children who placed below the 45th percentile. No significant (P greater than 0.05) between-group mean differences were noted for leg length, skeletal age, body coordination, or running economy (the aerobic demands at steady-state submaximal speeds). Significant (P less than 0.05) between-group mean differences were found for maximal aerobic power (A, 55.1; B, 48.6 ml X min-1 X kg-1), two-site skinfold sum (A, 15.2; B, 22.7 mm), and maximal sprinting speed (A, 359.7; B, 341.1 m X min-1). When compared with A runners, B runners performed 9-min runs at a higher percentage of their maximal speed (A, 58.0; B, 51.6%), required a higher VO2 to maintain this pace (A, 48.5; B, 40.8 ml X min-1 X kg-1), and exhibited higher 4.5-min post-run blood lactate levels (A, 9.1; B, 6.7 mM X 1(-1). It was concluded that post-exercise blood lactate levels are associated, and maturity and body composition are not associated with differences in distance-running performance in boys of this age.