The effect of rowing ergometry and resistive exercise on skeletal muscle structure and function during bed rest.
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. Twenty-seven healthy volunteers completed 5 wk of head-down-tilt bed rest (HDBR): 18 were randomized to exercise, 9 remained sedentary. Exercise consisted of rowing ergometry 6 days/wk, including interval training, and supplemental strength training 2 days/wk. Measurements before and after HDBR and following reambulation included assessment of strength, skeletal muscle volume (MRI), and muscle metabolism (magnetic resonance spectroscopy); quadriceps muscle biopsies were obtained to assess muscle fiber types, capillarization, and oxidative capacity. Sedentary bed rest (BR) led to decreased muscle volume (quadriceps: -9 ± 4%, P < 0.001; plantar flexors: -19 ± 6%, P < 0.001). Exercise (ExBR) reduced atrophy in the quadriceps (-5 ± 4%, interaction P = 0.018) and calf muscle, although to a lesser degree (-14 ± 6%, interaction P = 0.076). Knee extensor and plantar flexor 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 maximal O2 consumption, (31)P-MRS, and oxidative chain enzyme activity, was impaired in BR but stable or improved in ExBR. Reambulation reversed the negative impact of BR. 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.
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas; University of Texas Southwestern Medical Center at Dallas, Dallas, Texas; and.
Felix
F
Krainski
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas; University of Texas Southwestern Medical Center at Dallas, Dallas, Texas; and North Texas VA Medical Center, Dallas, Texas.
Jeffrey L
JL
Hastings
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas;
Katja
K
Heinicke
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas;
Nadine
N
Romain
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas;
Eric L
EL
Pacini
University of Texas Southwestern Medical Center at Dallas, Dallas, Texas; and.
Peter G
PG
Snell
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas;
Phil
P
Wyrick
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas;
M Dean
MD
Palmer
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas; University of Texas Southwestern Medical Center at Dallas, Dallas, Texas; and North Texas VA Medical Center, Dallas, Texas.
Ronald G
RG
Haller
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas; University of Texas Southwestern Medical Center at Dallas, Dallas, Texas; and BenjaminLevine@TexasHealth.org.
Benjamin D
BD
Levine
D000328:Adult; D001510:Bed Rest / Q000009:adverse effects*; D016552:Ergometry / Q000379:methods; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D018475:Head-Down Tilt / Q000502:physiology; D006801:Humans; D007717:Knee / Q000502:physiology; D007866:Leg / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D009133:Muscular Atrophy / Q000503:physiopathology; D055070:Resistance Training / Q000379:methods; D014893:Weightlessness; D018544:Weightlessness Countermeasures; D018474:Weightlessness Simulation / Q000379:methods
bed rest; deconditioning; exercise; microgravity; skeletal muscle