Evaluation of skeletal muscle oxidative capacity in persons with spinal cord injury with near-infrared spectroscopy
Erickson, Melissa Lynn
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PURPOSE: Evaluation of near-infrared spectroscopy (NIRS) as a method of assessing muscle metabolism in the spinal cord injury population (SCI). METHODS: Nine able-bodied (AB) and nine participants with SCI were tested in the vastus lateralis muscle. Electrical stimulation was used to increase metabolic rate and repeated brief arterial occlusions were used to measure metabolic rate. Time constants were calculated from the exponential recovery curve. Questionnaires were used to estimate spasm activity. RESULTS: The time constant was twice as slow in participants with SCI compared to AB participants (93.6 ± 43.9 vs. 38.7 ± 14.9 seconds, p = 0.005). Preliminary evidence supported relationships between time constants and injury duration, injury level, and muscle spasm activity. CONCLUSION: NIRS measurements of mitochondrial function suggest a 50% deficit in the group with SCI, consistent with previous studies using 31P MRS. Therefore, NIRS measurements may be used to better understand how SCI influences skeletal muscle.