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Concurrent exercise on a gravity-independent device during simulated microgravity
Joshua A Cotter1, Alvin Yu, Fadia Haddad
11Department of Physiology and Biophysics, University of California, Irvine, CA; 2Department of Orthopaedic Surgery, University of California, Irvine, CA; 3Department of Kinesiology, California State University, Long Beach, CA; and 4Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, SWEDEN.
High-intensity exercise using a gravity-independent device effectively maintained muscle function and aerobic capacity during simulated microgravity (unilateral lower limb suspension). This training mitigated muscle loss and improved performance markers.
Area of Science:
- Exercise Physiology
- Space Medicine
- Skeletal Muscle Biology
Background:
- Short-term unilateral lower limb suspension (ULLS) simulates microgravity effects, leading to skeletal muscle deconditioning and reduced aerobic capacity.
- Maintaining physical function is crucial for astronauts during space missions and for rehabilitation after injury.
Purpose of the Study:
- To investigate the efficacy of a high-intensity concurrent training program using a novel gravity-independent device.
- To assess the impact of this training on skeletal muscle function and aerobic capacity during a 10-day ULLS protocol.
Main Methods:
- Nineteen participants underwent 10 days of either ULLS only or ULLS combined with exercise (ULLS + EX).
- The ULLS + EX group utilized a Multi-Mode Exercise Device (M-MED) for alternating high-intensity aerobic and resistance training sessions.
- Muscle function, aerobic capacity, and molecular markers (myosin heavy-chain mRNA, myostatin, atrogin, citrate synthase) were analyzed.
Main Results:
- The ULLS + EX group showed a 7% increase in aerobic capacity and improved strength in knee extensors and ankle plantar flexors.
- Peak torque decreased with ULLS but was maintained or improved with ULLS + EX.
- Molecular changes associated with muscle atrophy (myostatin, atrogin) were mitigated in the vastus lateralis with ULLS + EX.
Conclusions:
- A gravity-independent exercise device (M-MED) can effectively counteract the deconditioning effects of simulated microgravity.
- High-intensity concurrent training is a viable countermeasure for preserving skeletal muscle function and aerobic capacity during ULLS.
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