Muscle Plasticity, Fitness, and Health after Spinal Cord Injury

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DESCRIPTION (provided by applicant): This proposed research is a revised competing continuation of a previous award. Our previous research showed that surface neuromuscular electrical stimulation (SNMES) can markedly increase muscle mass in individuals with complete spinal cord injury (SCI). We found pilot data that suggested that SNMES can also increase insulin action after complete SCI who are glucose tolerant. The general aim of this proposal is to extend our research to test whether exercise therapy can improve insulin action in complete SCI individuals who are either diabetic (DIA) or have impaired glucose tolerance (IGT). The specific aims are: 1) Can 3 months of resistance or endurance exercise therapy be affective at "treating" IGT or DIA in complete, SCI individuals; and 2) What are the physiological adaptations (increased muscle mass, decreased fat mass, increased muscle endurance) are responsible for the improved insulin action following SNMES-induced exercise therapy. 100 subjects (84 to start the program, 78 expected to finish) with complete SCI (either paraplegic or quadriplegic) who are either IGT or DIA, 18 to 55 yrs of age, will be studied over the next 5 yrs. The resistance training will consist of knee extensions with ankle weights, two sessions of 40 lifts per week for 3 months. The weight used will be increased as needed. Endurance exercise therapy will use twitch stimulations for 30 minutes three times per week. A control group (no exercise) will be used for comparison. The following techniques will be used to assess the efficacy of the therapies; an oral glucose tolerance test for insulin action, magnetic resonance imaging for muscle size and lipid deposits, and SNMES for the fatigue tests. Rejection of the null hypothesis will show that those with a complete SCI can use either residence-based, self-administered resistance or endurance exercise therapy to treat IGT/DIA and reduce the risk of cardiovascular disease. In addition, physiological adaptations that best predict changes in insulin action will be determined. A blocked design will be used to separately evaluate IGT and DIA. This research will address methods to prevent diabetes which is an important health problem in SCI. This study will also use practical self-administered exercise protocols, and will test links between insulin action and modifiable physiological functions. Thus, this research has the potential to significantly benefit people with spinal cord injuries.