Distribution of rest periods between electrically generated contractions in denervated muscles of rats.

Stimulation protocols for denervated muscles distribute the generated contractions either within treatment sessions followed by hours of rest, or repeated 24 h per day with each contraction followed by a constant interval of rest. Our purpose was to directly compare the effects of the same number of identically generated contractions having different temporal daily distributions. For 5 weeks in denervated extensor digitorum longus muscles of rats, between 100 and 800 contractions were generated daily, distributed either within worksets that alternated periods of activity and rest, or separated by constant intervals of rest. Most of the tested protocols maintained muscle mass and maximum force near values of innervated controls. Although 100 contractions daily generated at constant intervals were sufficient to maintain mass and force, 100 contractions during a 4-h treatment session followed by 20 h of rest were not sufficient, and mass and force were not different from values of denervated muscles.