Gabriel, D. A., & Boucher, J. P (2000) Practicing a maximal performance task: A cooperative strategy for muscle activity. Research Quarterly for Exercise and Sport, 71, 217-228.

The effect of practice on predicting elbow flexion movement time was studied. Ss (N = 18) performed 400 elbow-flexion trials to a horizontal target. Trials were distributed equally over four sessions. The goal was to decrease movement time while maintaining the same level of accuracy. EMG activity was monitored in the biceps and triceps brachii. Onset of muscle activity relative to the movement start (motor time), duration of muscle activity, and mean amplitude of the activity burst for the first 30 ms of activity were measured.

Early in learning, the magnitude of muscle activity was adjusted to increase movement speed. As practice continued, changes in muscle activity duration occurred to improve accuracy while magnitude changes were less involved. Late in the learning, both aspects of muscle activity were used to decrease movement time while preserving accuracy.

Implication. When attempting to decrease movement time in precise activities, a preferred hierarchy of attentional strategies in the learning progression would be:

• increase the targeted movement to the desired speed;
• then increase the effort level, particularly with regard to accuracy, at the newly attained speed; and
• then finally use an alternation of emphasis on speed and effort precision for further skill refinements.

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