Effects of therapeutic percutaneous electrical stimulation of atrophic human quadriceps on muscle composition, protein synthesis and contractile properties

Abstract

The effects of percutaneous electrical stimulation (70 V, 300 microseconds pulses at 30 Hz) on muscle composition and rate of protein synthesis were studied in seven patients with quadriceps atrophy secondary to unilateral osteoarthritis of the knee (stimulated group). Quadriceps were stimulated on the affected side for 1 h per day. The results were compared to those from seven patients who did not use a muscle stimulator (control group), in whom muscle biopsy at surgery provided evidence of wasting of tissue protein on the side of osteoarthritis (normal leg 608 +/- 266 micrograms protein micrograms-1 DNA, affected leg 256 +/- 100 micrograms protein micrograms-1 DNA, means +/- SD, P less than 0.05; type I fibre diameters: normal 53.2 +/- 6.7 microns, affected 43.8 +/- 4.0 microns, P less than 0.05). In patients who had received stimulation there was no residual difference between the legs in either muscle protein concentration (normal 411 +/- 168 micrograms protein micrograms-1 DNA, affected 373 +/- 112 micrograms protein micrograms-1 DNA) or fibre diameter (type I diameters: normal 56.1 +/- 7.8 microns, affected 58.0 +/- 10.7 microns). Stimulation did not influence the ratios of muscle force elicited by acute stimulation at 20 and 50 Hz (normal 75 +/- 15%, affected 79 +/- 15%), or rates of muscle relaxation (percentage losses of tetanic force 10 ms-1: normal 7.66 +/- 1.2%, affected 8.67 +/- 2.2%).(ABSTRACT TRUNCATED AT 250 WORDS)