Cardiometabolic Effects of High-Intensity Hybrid Functional Electrical Stimulation Exercise after Spinal Cord Injury

Introduction: The prevalence of cardiometabolic disease following spinal cord injury is known to be high. However, it is unknown whether engaging in high-intensity exercise, which is advocated by recent guidelines, is beneficial or feasible for these individuals. Objective: To assess the effects of high-intensity, whole-body exercise on the prevalence of cardiometabolic disease in individuals with spinal cord injury. Design: Combination of a randomized controlled trial and an open label intervention study of functional electrical stimulation legs plus arms rowing. Setting: Outpatient academic rehabilitation hospital. Participants: Forty individuals with spinal cord injury, with American Spinal Injury Association (ASIA) impairments scales A-D and neurological levels of injury C1-T12. Intervention: Six months of high-intensity, hybrid-functional electrical stimulation rowing. Main Outcome Measures: Change in VO_2max, serum lipids, and insulin resistance, prevalence of cardiometabolic disease. Results: Individuals averaged 42.1 ± 22.0 minutes of hybrid-functional electrical stimulation rowing a week over an average of 1.69 sessions per week over the 6 months of intervention. This amounted to an average of 170.9 ± 100 km rowed, at a mean heart rate of 82.7% of individualized maximum. Only one of 40 individuals met current exercise guidelines for the full 6 months. VO_2max increased significantly (P <.001), yet prevalence of cardiometabolic disease did not change significantly (decrease from 22.5% to 20%, P =.70). Hemoglobin A1c did decrease significantly over this time (P =.01), although serum lipids and fasting glucose/insulin levels were unchanged. In exploratory subanalyses assessing individuals injured ≤12 months, those with more chronic injuries decreased their triglyceride-to-high-density lipoprotein (HDL) ratio (P =.04), a marker of cardiac mortality. Stratifying by neurological level of injury, individuals with paraplegia had worsened low-density lipoprotein (LDL) level (P =.02) and total cholesterol-to-HDL ratio (P =.04) over the 6-month intervention. Conclusions: Sustained high-intensity exercise with hybrid functional electrical stimulation rowing does not decrease the prevalence of cardiometabolic disease after spinal cord injury.