Hetzler, R. K., DeRenne, C., Buxton, B. P., Ho, K. W., Chai, D. X., & Seichi, G. (1997). Effects of 12 weeks of strength training on anaerobic power in prepubescent male athletes. Journal of Strength and Conditioning Research, 11, 174-181.

Two groups of 10 prepubescent and pubescent male baseball players trained three times per week for 12 weeks using a variety of general free-weight and machine exercises designed for both strength and power acquisition. One group was experienced in strength training while the other comprised novices. A comparable control group (N = 10) did not perform the training program but did participate in all other non-experimental activities.

For the experienced, novice, and control groups respectively, the following gains were recorded: leg press -- 41%, 40%, and 14%; and bench press -- 23%, 18%, and 0%. Both training groups were significantly better than the control group. Similarly, the two training groups improved in vertical jump. However, the control group improved to a significantly greater degree in peak and mean anaerobic power and the 40-yard dash.

The training regime improved the training activities but did not transfer to functional performance measures. One could argue that the training actually caused anaerobic power and 40-yd dash measures to decrease, particularly in the experienced strength-training group.

The metabolic changes in training groups did not transfer changes in energy potential to dynamic cycling, supporting the principle of specificity. In particular, the high force/low velocity aspects of the training did not transfer to high velocity activities.

Implication. Strength and power exercises in pubescent males improved training exercises but produced worse performances in functional strength and power activities than in a non-training comparable group. Performance benefits from such training for this class of athlete are unlikely.

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