Effect of Stimulation Frequency on Efficiency of Muscle

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F. Abbate was one of Professor Anthony J Sargeant’s PhD students who submitted this published research as a chapter in his PhD thesis. The research was jointly supervised with Arnold de Haan.
Journal of Applied Physiology. 2002; 92(5):2089-96

ABSTRACT The influence of stimulation frequency on efficiency (= total work output/high-energy phosphate consumption) was studied using in situ medial gastrocnemius muscle tendon complexes of the rat. The muscles performed 20 repeated concentric contractions (2/s) at 34°C. During these repeated contractions, the muscle was stimulated via the severed sciatic nerve with either 60, 90, or 150 Hz.

The muscle was freeze-clamped immediately after these contractions, and high-energy phosphate consumption was determined by measuring intramuscular chemical change relative to control muscles. The average values (±SD) of efficiency calculated for 60, 90, and 150 Hz were 18.5 ± 1.5 (n = 7), 18.6 ± 1.5 (n = 9), and 14.7 ± 1.3 mJ/μmol phosphate (n = 9). The results indicate that the efficiency of the muscles that were submaximally activated (60 or 90 Hz) was higher (+26%,P < 0.05) than that of those maximally activated (150 Hz). Additional experiments showed that the low efficiency at maximal activation levels is unlikely to be the result of a higher energy turnover by the Ca2+-ATPase relative to the total energy turnover. Therefore, alternative explanations are discussed.

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