Short-arm centrifugation as a partially effective musculoskeletal countermeasure during 5-day head-down tilt bed rest-results from the BRAG1 study

• Human centrifugation, also called artificial gravity (AG), is proposed as a combined strategy against detrimental effects of microgravity in long-term space missions. This study scrutinized human short-arm centrifugation as countermeasure against musculoskeletal de-conditioning. Eleven healthy male subjects [mean age of 34 (SD 7) years] completed the cross-over trial, including three campaigns of -6A degrees head-down tilt bed rest (HDT) for 5 days, with preceding baseline data collection and recovery phases. Bed rest without AG was used as control condition (Ctrl), and AG with 1 g at the center of mass applied once per day for 30 min in one bout (AG(1x30)) and in 6 bouts of 5 min (AG(6x5), 3-min rest between bouts) as experimental conditions. End-points were muscle strength, vertical jump performance, and biomarkers of bone and protein metabolism. AG(6x5) was better tolerated than AG(1x30). Bone resorption markers CTX, NTX, and DPD all increased by approximately 25 % toward the end of bed rest (P < 0.001), and nitrogen balance decreased by approximately 3 g/day (P < 0.001), without any protection by AG (P > 0.4). Decreases in vertical jump height by 2.1 (SE 0.6) cm after Ctrl bed rest was prevented by either of the AG protocols (P = 0.039). The present study yielded succinct catabolic effects upon muscle and bone metabolism that were un-prevented by AG. The preservation of vertical jump performance by AG in this study is likely caused by central nervous rather than by peripheral musculoskeletal effects.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

Nyckelord

Bed rest

Human physiology

Artificial gravity

Space flight

De-conditioning

Countermeasures

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