MUSCULOSKELETAL OUTCOMES FROM CHRONIC HIGH-SPEED HIGH-IMPACT RESISTANCE EXERCISE

摘要

Purpose: Preventing excessive bone resorption on long-term microgravity missions is crucial to astronaut health, and muscular and bone countermeasures often are at odds with each other. Osteocytes within bone sense strain and adapt to microfractures and stress by promoting bone formation. Current and proposed microgravity workouts do not involve repeated high-speed, high-impact countermeasures. The use of a gravity-independent, high-speed, high-impact resistive device was used to induce bone formation and inhibit bone resorption while optimizing peak torque on musculature. Methodology: 13 healthy subjects performed 30 sessions of resistive exercise on the Inertial Exercise Trainer (IET) with their left leg, with the right legs as untreated matched controls. Measurements taken before and after treatment include peak torque (PT), time to peak torque (TPTT), lower body DEXA scans, alkaline phosphatase, c-terminal telopeptides of type-I collagen, and isokinetic strength. Food logs measured kilocalorie, protein and calcium intakes. Results: One-way ANOVAs showed non-significant changes in dietary kilocalorie, protein Ca+2 intakes. 2 (leg) x 2 (time) ANOVAs, w/repeated measures on both IV, showed Inertial Exercise Training led to significant left knee and ankle gains in peak torque without significant decreases in time to peak torque. 2 x 2 ANCOVAs, w/repeated measures on both IV scan area as a covariate, showed calcaneal BMD BMC significantly increased from Inertial Exercise Training. T-tests revealed Inertial Exercise Training led to a significant decline in type-I collagen Cterminal telopeptides, a marker of bone resorption. Conclusion: The device delivers torque comparable to standard exercise equipment in a gravity-independent format, though ease of use, as indicated by time to peak torque, needs further adjustment. Bone density and calcification significantly increased from IET use, bone resorption markers were significantly decreased, and there were significant gai