Hoff, J., & Berdahl, G. O. (2000). Load dependent strength training effects on power production and performance. Medicine and Science in Sports and Exercise, 32(5), Supplement abstract 658.

The literature proposes that light loads (30% 1 RM) and heavy loads (85% 1 RM) are the appropriate loads to improve dynamic athletic performance, usually the vertical jump. In these formulations, body weight is seldom considered. It could be an important factor. This investigation used male soccer players performing half-squats under different treatments.

• A control group (N = 10).
• A body-weight alone group doing simulated training without external loads (N = 11).
• A group using an external load of 30% of 1 RM squats (N = 10).
• A group using an external load of 85% of 1 RM squats (N = 10)

When performing the exercises in the treatment groups, emphasis was placed on the maximal mobilization of force in the concentric portion of the half-squat. Training was 4 x 5 repetitions, three times per week for seven weeks. After each squat training, 3 x 5 vertical counter-movement jumps were performed.

In both externally loaded groups, 1 RM increased. Vertical jump improved only in the highest training load group but only when the vertical jump was performed with a 50-kg weight. Vertical jump measures did not improve in unweighted or light-loaded jumping protocols. The highest power production occurred when jumping without any external load. Sprinting tests of 10 and 40 m improved only in the highest-load training group.

It was concluded that improving vertical jumping height involved more than just the training load in resistance training. The specificity of the training effects of resistance exercises is again demonstrated in this investigation. There is little to no carry-over of training benefits to actual dynamic performance. However, why sprint times improved and the specifically targeted vertical jump did not is not addressed. One could propose that sprinting is improved by strength training, but since the training employed only the half-squat, which is more related to vertical jumping and less so to sprinting, the effects are puzzling.

Implication. The effects of strength training activities on the performance of a dynamic vertical jump are minimal at best.

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