Purpose: To determine the effects of age, gender, and ethnicity on the predicted aerobic power of youth as they age from 8 to 16 yr.
Methods: The sample was a multicohort group of 2540 African Americans (N = 543) and Caucasians (N = 1997), 1279 (50.4%) girls and 1261 (49.6%) boys. Heights, weights, and sum of skin folds (triceps + subscapular) were measured. Aerobic power ((p)VO(2max)), expressed in relative (mL x kg(-1) x min(-1)) or absolute (L x min(-1)) terms, was predicted from a three-stage cycle ergometry test.
Results: Quadratic mixed-model analysis indicated that boys had higher relative and absolute (p)VO(2max) than the girls (P = 0.0004). The African American subjects had a higher absolute (p)VO(2max) (L x min(-1)) than the Caucasians, but their relative (p)VO(2max) was lower than the Caucasians (P = 0.031). Finally, age had a significant effect on (p)VO(2max) (P = 0.0001). The absolute (p)VO(2max) of the girls increased 9%.yr(-1) until age 14; but their relative (p)VO(2max) declined approximately 1.2 mL x kg(-1) x min(-1) x yr(-1). The absolute (p)VO(2max) for the boys increased yearly by approximately 14% from ages 8 to 16 yr, but the relative (p)VO(2max) of the African American males was stable from ages 8 to 11, then dropped, and stabilized again between ages 12 and 16 yr. The relative (p)VO(2max) of the Caucasian boys declined from ages 8 to 10, but then increased slightly from age 12 to 16 yr. In addition, the interactions of age and gender, and age squared and gender were significant (P < 0.02).
Conclusion: These data indicate that although absolute (p)VO(2max) (L x min(-1)) increases from age 8 to 16 yr, relative (p)VO(2max) (mL x kg(-1) x min(-1)) declines. The decline appears to be related to increased fat mass. Similarly, the higher relative (p)VO(2max) (mL x kg(-1) x min(-1)) of the Caucasian youth compared with the African American youth was related to lower weights and skin folds of the Caucasian youth.