Evaluation of muscle metabolism in individuals with spinal cord injury
Mulcahy, Tara Kristin
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Individuals with a spinal cord injury (SCI) are at risk of cardiovascular disease and diabetes. Impaired muscle oxidative metabolism could contribute to disease risk. The purpose of this study was to evaluate oxidative muscle metabolism in the legs of people after spinal cord injury using the rate of phosphocreatine (PCr) resynthesis after exercise. A second purpose was to evaluate PCr recovery rate following voluntary exercise and electrical stimulation in able-bodied subjects. PCr resynthesis was measured after electrical stimulation or exercise using 31P magnetic resonance spectroscopy with a 10 cm surface coil placed over the right vastus lateralis in a 3 Tesla magnetic resonance spectrometer. Subjects with SCI were electrically stimulated for 60 seconds at 4 Hz. The able-bodied subjects first performed a 39-second maximal voluntary isometric contraction and electrical stimulation at 4 Hz for 60-90 seconds (113). PCr recovery rate was 42.7 seconds mean (SD) and 82.4 ± (30.6) seconds for AB and SCI subjects, respectfully. In AB subjects, PCr recovery rate was 25.9 ± (4.7) seconds following voluntary exercise. In conclusion, mitochondrial capacity in paralyzed muscle as measured by PCr recovery rates was 93% lower than able-bodied subjects. This decrease in mitochondrial capacity may play a role in the decline in insulin sensitivity in people with SCI.