Background: Exposure to microgravity causes functional and structural impairment of skeletal muscle. Current exercise regimens are time-consuming and insufficiently effective; an integrated countermeasure is needed that addresses musculoskeletal along with cardiovascular health. High-intensity, short-duration rowing ergometry and supplemental resistive strength exercise may achieve these goals. Methods: 27 healthy volunteers completed 5 weeks of head down tilt bed rest; 18 were randomized to exercise, 9 remained sedentary. Exercise consisted of rowing ergometry 6d/week including interval training, and supplemental strength training 2d/week. Measurements before and after bed rest, and following reambulation included assessment of strength, skeletal muscle volume (MRI), and muscle metabolism (MRS); quadriceps muscle biopsies were obtained to assess muscle fiber types, capillarization and oxidative capacity. Results: Sedentary bed rest (BR) led to decreased muscle volume (quadriceps: -9±4%, p<0.001; plantarflexors: -19±6%, p<0.001). Exercise (ExBR) reduced atrophy in the quadriceps (-5±4%, interaction p=0.018) and calf muscle, though to a lesser degree (-14±6%, interaction p=0.076). Knee extensor and plantarflexor strength was impaired by BR (-14±15%, p=0.014 and -22±7%, p=0.001) but preserved by ExBR (-4±13%, p=0.238 and +13±28%, p=0.011). Metabolic capacity as assessed by VO2max, (31)P-MRS and oxidative chain enzyme activity was impaired in BR but stable or improved in ExBR. Reambulation reversed the negative impact of bed rest. Conclusions: High-intensity, short-duration rowing and supplemental strength training effectively preserved skeletal muscle function and structure while partially preventing atrophy in key antigravity muscles. Due to its integrated cardiovascular benefits, rowing ergometry could be a primary component of exercise prescriptions for astronauts or patients suffering from severe deconditioning.
- Bed Rest
- Skeletal Muscle
- Copyright © 2013, Journal of Applied Physiology