Bosco, C., Rusko, H., & Hirvonen, J. (1984). The effect of extra-load conditioning on muscle performance in athletes. Medicine and Science in Sports and Exercise, 18, 415-419.

Two groups of seven Ss, one a control and the other an experimental group whose members wore a weighted vest (7-8% body weight) all day including training except when skill acquisition activities occurred. All Ss were sprinters who no longer were improving.

After three weeks, control Ss showed no changes in either physical or mechanical properties. The experimental group's force-velocity curve shifted to the right, meaning that they were able to exert more force at original speeds. Performance changes occurred in 15 sec jumping and the drop jump test.

This investigation showed biological adaptation to strength training occurs in both neurogenic and myogenic muscle components. Neural changes appear first and improve technique, increase the firing rate of motor units, recruit additional motor units, and improve the synchronization of motor units. Morphological adaptations occur later and only after neural adaptations are exhausted.

Implication. Initial strength training is purely a motor skill development activity where the central nervous system harnesses existing resources to perform the strength activities more efficiently and to exploit the structures of muscle more effectively. Discrete skill learning of this nature will not transfer/generalize to other activities in highly skilled performers.

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