OBJECTIVE: To investigate the effect of unilateral cast immobilization with and without surface electrical stimulation (ES) on the tibialis anterior (TA) muscle of rabbits. DESIGN: Prospective randomized trial. SETTING: University medical school. ANIMALS: 53 New Zealand White rabbits (aged 54 to 63 days, weight 1.73 to 1.91 kg). METHODS AND INTERVENTION: Random assignment, for a 3-week period, to one of four groups: C group (control group), I group (immobilization group), S group (group of electrical stimulation which was stimulated isometrically at 50 Hz, 30 minutes per day, 5 times a week), and IS group (immobilization group which, like the S-group, received electrical stimulation). OUTCOME MEASURES: Muscle wet wight, muscle fiber cross-sectional area, muscle fiber types, and muscle capillary supply. RESULTS: Muscle wet weight decreased significantly in the I group by 19% (p < or = .05), with a corresponding significant reduction in the total muscle fiber cross-sectional area of 26% (p < or = .05). No significant changes were observed in muscle wet weight and muscle fiber cross-sectional area in the S and IS groups. Interstitial fibrosis was observed in the I group and occasionally in the IS group. No significant changes in the total number of muscle fiber types I and II were found in all experimental groups. The capillary supply of the S and IS groups did not change significantly. However, capillary-to-fiber ratio was significantly reduced by 20% with a simultaneously nonsignificant increase in capillary density (capillaries/mm2) of 11% (p > .05) in the I group. Furthermore, muscle fiber regeneration was observed predominantly in the I group. CONCLUSIONS: In this experimental model, ES effectively prevented immobilization-induced muscle atrophy by minimizing reduction of muscle fiber cross-sectional area, interstitial fibrosis, and impaired blood supply.
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