title: Artificial gravity with ergometric exercise as a countermeasure against cardiovascular deconditioning during 4 days of head-down bed rest in humans.
abstract: We have shown previously that combined short-arm centrifuge and aerobic exercise training preserved several physiologically important cardiovascular functions in humans. We hypothesized that artificial gravity (AG) and exercise is effective to prevent changes of physical problems during head-down bed rest (HDBR). To test this hypothesis, 12 healthy male subjects had undergone 4 days of 6° HDBR. Six of them were exposed to AG of an alternating 2-min intervals of +1.0 and +2.0 Gz at foot level for 30 min twice per day with ergometric exercise of 40 W as a countermeasure during bed rest (CM group), while the remaining six served as untreated controls (no-CM group). Before and after 4 days of bed rest, leg venous hemodynamics was assessed by venous occlusion plethysmography and autonomic cardiovascular control estimated by power spectral analysis of blood pressure and heart rate. Further, orthostatic tolerance was evaluated by a 75° head-up tilt test and physical working capacity was surveyed by near maximal physical working capacity test before and after bed rest. The data showed that combined centrifuge and exercise applied twice daily for a total of 60 min during 4 days of HDBR prevented (a) a decrease in working capacity, (b) autonomic dysfunction (a decrease in the activity of parasympathetic cardiac innervation) and (c) an increase in leg venous flow resistance. The combination of a 30 min alternating of +1.0 and +2.0 Gz for twice per day of AG with 40 W ergometric exercise may offer a promising countermeasure to short duration simulated microgravity.
authors.affiliation: Department of Aerospace Biodynamics, Faculty of Aerospace Medicine, Fourth Military Medical University, 17 Chang Le Xi Road, Xi'an 710032, China.
authors.forename: Yong-Chun
authors.initials: YC
authors.lastname: Wang
authors.forename: Chang-Bin
authors.initials: CB
authors.lastname: Yang
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Wu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Gao
authors.forename: Dong-Yuan
authors.initials: DY
authors.lastname: Lu
authors.forename: Fei
authors.initials: F
authors.lastname: Shi
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Wei
authors.forename: Xi-Qing
authors.initials: XQ
authors.lastname: Sun
mesh_terms: D000328:Adult; D001510:Bed Rest / Q000009:adverse effects; D001794:Blood Pressure / Q000502:physiology; D018493:Cardiovascular Deconditioning / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D018470:Gravity, Altered / Q000009:adverse effects; D018475:Head-Down Tilt / Q000009:adverse effects / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D013997:Time Factors; D018544:Weightlessness Countermeasures; D018474:Weightlessness Simulation / Q000379:methods; D055815:Young Adult