Objective To analyze the effect of biological maturation on training‐induced strength and endurance adaptations in the prepubertal growth spurt. Methods One hundred and twenty‐five healthy children (58 boys, 67 girls), aged 10–11 years old (10.8 ± 0.4 years), who were self‐assessed as belonging to Tanner stages I and II, were randomly divided into two experimental groups, a strength training group (19 boys, 22 girls) and an endurance training group (21 boys, 24 girls) that would train twice a week for 8 weeks, as well as a control group (18 boys, 21 girls; no training program). Results After 8 weeks of training, there were improvements in all strength and endurance measures (P < 0.01) for both groups of Tanner stage I and II children. No significant differences in training response were observed relative to biological maturity or gender (P > 0.05). Conclusions These data suggest that more biologically mature prepubescent children seem to have no advantage in training‐induced strength and endurance adaptations compared with their less mature peers. Additionally, gender did not affect the training‐induced changes in strength or aerobic fitness. These results are meaningful for the development of optimized well‐rounded training programs in prepubertal children. Am. J. Hum. Biol., 2014. © 2014 Wiley Periodicals, Inc.