Muscle Size After 24 Weeks Of Electrically-stimulated Resistance Training In Individuals With Spinal Cord Injury

Abstract

Complete spinal cord injury (SCI) leads to many profound physiological adaptations, including dramatic loss of skeletal muscle mass below the point of spinal lesion. PURPOSE To examine the effect of 24 weeks of neuromuscular electrical stimulation (NMES)-evoked resistance training on affected skeletal muscle size in individuals with long-term SCI. METHODS Five men with chronic, complete SCI (levels C5-T10) participated in this study. Average subject age and duration of injury was 35.6 and 13.4 yrs, respectively. Magnetic resonance images (MRI) of the thighs were collected before and after 24 weeks of training. The resistance training was performed at each subject's home where investigators provided instruction by telephone for each session. Subjects trained both thighs with NMES-evoked dynamic, loaded knee extensions 2 days/week for 4 sets of 10 repetitions. NMES activated primarily the quadriceps femoris (QF) muscle group and stimulation amplitude was increased during each repetition to evoke full knee extension. RESULTS After training, skeletal muscle cross sectional area (CSA) increased 64% in the right QF (32.6 ± 11.2 to 53.3 ± 10.3 cm2, p = 0.004) and 67% in the left QF (34.6 ± 11.5 to 57.6 ± 14.9 cm2, p = 0.002), roughly equivalent to ±70% of CSA of able-bodied men (±80 cm2). CONCLUSIONS These results demonstrate that paralyzed skeletal muscle can still achieve substantial hypertrophy years after SCI with NMES-evoked resistance exercise. Supported by HD 39676 and HD 39676S2 to GAD