Strength training for prepubescent males: is it safe?

This study examined the safety of one type of strength training for prepubescent males. Eighteen males (average age, 8.3 +/- 1.2 years) participated in a 45 min/session, three session/week, 14 week supervised strength training program with an attendance rate of 91.5%. Concentric work was done almost exclusively. KinCom analysis showed significant strength gain in this group (P less than 0.05), while an age, sex, and activity matched control group did not gain strength. Safety was evaluated by injury surveillance, blood pressure and heart rate monitoring, scintigraphy, and creatine phosphokinase measurement. Effects on growth and development, flexibility, and motor performance were also investigated, as these are factors with an impact on sports injury occurrence. Results showed that in the short term, supervised concentric strength training results in a low injury rate and does not adversely affect bone, muscle, or epiphyses; nor does it adversely affect growth, development, flexibility, or motor performance. As the safety question is multifaceted, this should not lead to the conclusion that strength training for prepubescents is uniformly safe. Further research is needed.