LEARNING IS BEST ACCOMPLISHED IN A NON-FATIGUED STATE
Barnett, M. L., Ross, D., Schmidt, A., & Todd, B. (1973). Motor skill learning and the specificity of training principle. Research Quarterly, 44, 440-447.
Fatigue alters the recruitment pattern and intensity of work of a muscle's motor units. If one considered an interpretation of the specificity of training principle, that training should be done under the conditions of appropriate fatigue, it would seem that "criterion" conditions could be defined.
In this study, two models of skill training were compared. The first was the "criterion" condition that employed appropriate stress, while the other was the "optimal" condition that was to generate the highest level of performance practice.
Although the results of skill learning were not significantly different, which could be due to an artifact of the experimental design used, the data indicated that the non-fatigued learning condition was superior to fatigued learning.
Implication. When learning a skill it is best to practice in non-fatigued conditions whether or not the skill would eventually be performed in fatigue. This would seem to be a contradiction of the specificity principle but that is a wrong impression. The establishment of neuromuscular skill patterns is best achieved in non-fatigued states. When a skill is overlearned to a desired level of proficiency then it can be practiced under difficult and environmental specific cues (e.g., crowd noises).
The principle of specificity should never be used to override the dictates of a basic principle of learning: initial learning occurs best in the absence of distractions and fatigue.