Bedrest induces a loss of muscle mass and function at the whole-muscle and single-cell levels, and ultimately a loss in physical function. We have consistently shown that muscle loading with resistance exercise during bedrest or unloading for 12-90 days can offset this loss of muscle mass and function. Currently, the standard of care for bedresting elderly is to perform loading equivalent to their body weight through a small amount of walking each day. The efficacy of this recommendation, however, has not been systematically examined at the whole-muscle and cellular levels. In fact, the incidence of falls in the elderly is significantly increased in the first month after discharge from a hospital stay. The goal of this project is to document the influence of bedrest on muscle mass and function at the whole-muscle and single-myofiber levels, as well as muscle protein metabolism in the elderly. An additional goal is to compare the influence of the standard-of-care walking exercise with that of a resistance training regimen known to be effective at preserving muscle mass, function, and metabolism during bedrest. We propose to study three groups of older (65-80 years) women and men who complete 10 days of bedrest: (1) those who do not complete any formal exercise during the bedrest period (BR), (2) those who complete resistance exercise (RE) three times during bedrest (BR+RE), and (3) those who perform the standard-of-care walking exercise (WE) daily (BR+WE). We will examine whole-muscle strength and size (by magnetic resonance imaging), fractional rate of muscle protein synthesis (FSR), and single-fiber contractile characteristics (size, strength, and power) before and after 10 days of bedrest. We hypothesize that whole-muscle and single-myofiber strength and size, as well as FSR, will be decreased with BR. We also hypothesize that these variables will be preserved with resistance exercise (BR+RE) but will not be maintained with the standard-of-care exercise (BR+WE). The investigators in this project have an extensive amount of experience in all of the proposed methodologies, specifically as they relate to bedrest. This investigation will provide important information for clinicians and physical therapists, as well as for older individuals, about the underlying basis of the loss of physical function that occurs as a result of bedrest in the elderly, and about the role of exercise in the treatment of bedrested elderly.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Program Projects (P01)
Project #
5P01AG023591-05
Application #
7620964
Study Section
Special Emphasis Panel (ZAG1)
Project Start
Project End
Budget Start
2008-06-01
Budget End
2009-05-31
Support Year
5
Fiscal Year
2008
Total Cost
$45,654
Indirect Cost
Name
University of Arkansas for Medical Sciences
Department
Type
DUNS #
122452563
City
Little Rock
State
AR
Country
United States
Zip Code
72205
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Coker, Robert H; Hays, Nicholas P; Williams, Rick H et al. (2014) Bed rest worsens impairments in fat and glucose metabolism in older, overweight adults. J Gerontol A Biol Sci Med Sci 69:363-70
Coker, Robert H; Wolfe, Robert R (2012) Bedrest and sarcopenia. Curr Opin Clin Nutr Metab Care 15:7-11
Tuvdendorj, Demidmaa; Chinkes, David L; Zhang, Xiao-Jun et al. (2011) Skeletal muscle is anabolically unresponsive to an amino acid infusion in pediatric burn patients 6 months postinjury. Ann Surg 253:592-7
Ferrando, Arny A; Paddon-Jones, Doug; Hays, Nicholas P et al. (2010) EAA supplementation to increase nitrogen intake improves muscle function during bed rest in the elderly. Clin Nutr 29:18-23
Hays, Nicholas P; Roberts, Susan B (2008) Aspects of eating behaviors ""disinhibition"" and ""restraint"" are related to weight gain and BMI in women. Obesity (Silver Spring) 16:52-8
Kortebein, Patrick; Symons, T Brock; Ferrando, Arny et al. (2008) Functional impact of 10 days of bed rest in healthy older adults. J Gerontol A Biol Sci Med Sci 63:1076-81
Borsheim, Elisabet; Bui, Quynh-Uyen T; Tissier, Sandrine et al. (2008) Effect of amino acid supplementation on muscle mass, strength and physical function in elderly. Clin Nutr 27:189-95
Kortebein, Patrick; Ferrando, Arny; Lombeida, Juan et al. (2007) Effect of 10 days of bed rest on skeletal muscle in healthy older adults. JAMA 297:1772-4
Wolfe, Robert R (2006) Optimal nutrition, exercise, and hormonal therapy promote muscle anabolism in the elderly. J Am Coll Surg 202:176-80

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