title: WISE 2005: Aerobic and resistive countermeasures prevent paraspinal muscle deconditioning during 60-day bed rest in women.
abstract: Microgravity-induced lumbar paraspinal muscle deconditioning may contribute to back pain commonly experienced by astronauts and may increase the risk of postflight injury. We hypothesized that a combined resistive and aerobic exercise countermeasure protocol that included spinal loading would mitigate lumbar paraspinal muscle deconditioning during 60 days of bed rest in women. Sixteen women underwent 60-day, 6° head-down-tilt bed rest (BR) and were randomized into control and exercise groups. During bed rest the control group performed no exercise. The exercise group performed supine treadmill exercise within lower body negative pressure (LBNP) for 3-4 days/wk and flywheel resistive exercise for 2-3 days/wk. Paraspinal muscle cross-sectional area (CSA) was measured using a lumbar spine MRI sequence before and after BR. In addition, isokinetic spinal flexion and extension strengths were measured before and after BR. Data are presented as means ± SD. Total lumbar paraspinal muscle CSA decreased significantly more in controls (10.9 ± 3.4%) than in exercisers (4.3 ± 3.4%; P < 0.05). The erector spinae was the primary contributor (76%) to total lumbar paraspinal muscle loss. Moreover, exercise attenuated isokinetic spinal extension loss (-4.3 ± 4.5%), compared with controls (-16.6 ± 11.2%; P < 0.05). In conclusion, LBNP treadmill and flywheel resistive exercises during simulated microgravity mitigate decrements in lumbar paraspinal muscle structure and spine function. Therefore spaceflight exercise countermeasures that attempt to reproduce spinal loads experienced on Earth may mitigate spinal deconditioning during long-duration space travel.
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Diego, California;
authors.forename: Jacquelyn A
authors.initials: JA
authors.lastname: Holt
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Diego, California; brandon.r.macias@nasa.gov.
authors.forename: Brandon R
authors.initials: BR
authors.lastname: Macias
authors.affiliation: University of New Mexico, Albuquerque, New Mexico;
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Schneider
authors.affiliation: Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas; and.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Watenpaugh
authors.affiliation: Wyle Science, Technology, and Engineering Group, Houston, Texas.
authors.forename: Stuart M C
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Diego, California;
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Chang
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Diego, California;
authors.forename: Alan R
authors.initials: AR
authors.lastname: Hargens
mesh_terms: D018480:Astronauts; D001510:Bed Rest / Q000009:adverse effects*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D018475:Head-Down Tilt / Q000502:physiology; D006801:Humans; D008150:Lower Body Negative Pressure / Q000379:methods; D008159:Lumbar Vertebrae / Q000502:physiology; D008161:Lumbosacral Region / Q000502:physiology; D064170:Paraspinal Muscles / Q000502:physiology*; D055070:Resistance Training / Q000379:methods; D013026:Space Flight / Q000379:methods; D014893:Weightlessness / Q000009:adverse effects*; D018544:Weightlessness Countermeasures; D018474:Weightlessness Simulation / Q000379:methods
keywords: disuse; erector spinae; exercise training; muscle atrophy; spaceflight