Electrically Induced Resistance Training in Individuals With Motor Complete Spinal Cord Injury

Abstract

ObjectiveTo examine the effects of 16 weeks of electrically induced resistance training on insulin resistance and glucose tolerance, and changes in muscle size, composition, and metabolism in paralyzed muscle. DesignPre-post intervention. SettingUniversity-based trial. ParticipantsParticipants (N=14; 11 men and 3 women) with chronic (>2y post spinal cord injury), motor complete spinal cord injury. InterventionHome-based electrically induced resistance exercise training twice weekly for 16 weeks. Main Outcome MeasuresPlasma glucose and insulin throughout a standard clinical oral glucose tolerance test, thigh muscle and fat mass via dual-energy x-ray absorptiometry, quadriceps and hamstrings muscle size and composition via magnetic resonance imaging, and muscle oxidative metabolism using phosphorus magnetic resonance spectroscopy. ResultsMuscle mass increased in all participants (mean ± SD, 39%±27%; range, 5%–84%). The mean change ± SD in intramuscular fat was 3%±22%. Phosphocreatine mean recovery time constants ± SD were 102±24 and 77±18 seconds before and after electrical stimulation-induced resistance training, respectively (P<.05). There was no improvement in fasting blood glucose levels, homeostatic model assessment calculated insulin resistance, 2-hour insulin, or 2-hour glucose. ConclusionsSixteen weeks of electrical stimulation-induced resistance training increased muscle mass, but did not reduce intramuscular fat. Similarly, factors associated with insulin resistance or glucose tolerance did not improve with training. We did find a 25% improvement in mitochondrial function, as measured by phosphocreatine recovery rates. Larger improvements in mitochondrial function may translate into improved glucose tolerance and insulin resistance.