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The Effects of Low‐Intensity Exercise during Bed Rest in Healthy Older Adults
Author(s) -
Galvan Fego,
ArentsonLantz Emily,
Nagamma Sneha,
Deer Rachel R.,
Fry Christopher S.,
Wacher Adam,
PaddonJones Douglas
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.713.6
Subject(s) - bed rest , medicine , isometric exercise , population , sarcopenia , intensity (physics) , lean body mass , cardiology , physical therapy , body weight , physics , environmental health , quantum mechanics
Aging results in the involuntary loss of muscle mass and strength. These rates of decline are exacerbated with hospitalization, illness, and injury (i.e., catabolic stressors). Acutely ill, hospitalized adults have significantly reduced daily activity (~740 steps/day) compared to their healthy counterparts (~6250 steps/day). While intense exercise is clearly not practical for older, hospitalized individuals, low‐intensity exercise may be a more practical alternative. 60 minutes of daily longitudinal loading (1G artificial gravity/centrifugation) has been shown to maintain muscle protein synthesis during bed rest in a young adult population. Thus, we hypothesized that low‐intensity exercise (2,000 steps/day) would mitigate the loss of muscle mass and function during 7‐days of bed rest in healthy older adults. We employed a 7‐day bed rest protocol as a model of the physical inactivity associated with hospitalization. Dietary intake and daily steps were strictly controlled. Volunteers were randomized into two experimental groups: bed rest alone (CON: N=10, 68±5 y) or bed rest + 2,000 daily steps (STEP: N=7, 68±6 y). Isometric strength, leg lean mass (LLM) and blood glucose area under the curve (AUC) were assessed at baseline and after 7‐days of bed rest. Changes in isokinetic extension (60°/s) (CON: −13.3±3.3 N·m vs STEP: −14.4±3.8 N·m), LLM (CON: −932.3±181.8 g vs STEP: −700.4±149.2 g), and blood glucose AUC (CON: 456.4±1016.5 mg/dl/120 min vs STEP: −901.4±986.4 mg/dl/120 min) were similar between groups. Data from this ongoing clinical trial suggests that a single bout of 2,000 steps/day is not sufficient to counter the catabolic effects of 7‐days bed rest in healthy older adults. Future exploration of the effects of a greater number of steps/day, the combined effects of nutritional support plus exercise or distributing activity across the day may be needed to have clinically translatable benefits. Support or Funding Information Supported by RO1 NR012973, P30 AG024832.