Heusner, W. (no date). Specificity of interval training. Unpublished manuscript, Michigan State University, East Lansing, MI. (p. 13)

Training has a specific action in relation to lactic acid production during heavy muscular work. The specificity is located in the muscles.

Training specificity applies between sports, events within sports, and between precise skills, paces, and effort levels. It is the neuromuscular patterning which differentiates the different actions, intensities, and muscle fiber recruitment. It has been shown that a training program which will increase elbow flexor strength at the waist has no effect on the muscles when the arm is overhead (Heusner, p. 13).

Minor adjustments in technique in trained athletes produce a loss in efficiency. Thus, it is important to determine when and when not to change techniques because of the degrading effect upon performance.

As long as technique remains unchanged, an energy expenditure plateau in performance is reached. Thus, unless technique is changed performance peaks and then does not improve any more from a biomechanical or physiological perspective.

As technique changes are implemented, athletes oscillate between improving and decreasing levels of efficiency. This could account for non-perceived improvement. Indications of non-specific or unrelated training are:

• muscle soreness in recovery,
• acute localized fatigue,
• subjective appraisal of work being harder than usual, and
• quick onset of fatigue.

Implication. Training increases skill for the activity at the particular work intensity that is practiced. It does not generalize such training effects.

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