TY - JOUR
T1 - The importance of muscle versus fat mass in sarcopenic obesity
T2 - A re-evaluation using D3-creatine muscle mass versus DXA lean mass measurements
AU - Osteoporotic Fractures in Men (MrOS) Study Research Group
AU - Orwoll, Eric S.
AU - Peters, Katherine E.
AU - Hellerstein, Marc
AU - Cummings, Steven R.
AU - Evans, William J.
AU - Cawthon, Peggy M.
N1 - Publisher Copyright:
© The Author(s) 2020. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved.
PY - 2020
Y1 - 2020
N2 - Background: The combination of sarcopenia and obesity has been associated with physical impairment in older people. However, previous research has relied on assessments of lean mass as a surrogate for muscle mass. We postulate that inaccurate measures of muscle mass may have obscured the role of obesity in sarcopenia and related outcomes. Our aim was to clarify the interactions of muscle and fat with physical performance and adverse outcomes using an accurate measure of muscle mass. Methods: In a longitudinal study of >1,300 older men (mean age 84 years), we compared a direct measurement of muscle mass (D3 creatine dilution; D3Cr) with an approximation of muscle mass (appendicular lean mass [ALM] by dual-energy x-ray absorptiometry [DXA]) and their associations with measures of physical performance (gait speed, chair stand time) and adverse outcomes (incident injurious falls and mobility problems). We measured percent fat mass by DXA. Results: Low D3Cr muscle mass was strongly associated with decreased performance and increased risk of adverse outcomes. Increased fat mass had little association after accounting for D3Cr muscle mass. In contrast, DXA ALM was minimally associated with performance or adverse outcomes, and fatness remained associated with both outcomes after accounting for DXA ALM. Conclusions: When an accurate assessment of muscle mass (rather than lean mass) is used, reduced muscle mass is highly associated with important outcomes and the negative effects of adiposity are minimal, suggesting that obesity has little relevance for the understanding of important adverse health outcomes of sarcopenia in older men.
AB - Background: The combination of sarcopenia and obesity has been associated with physical impairment in older people. However, previous research has relied on assessments of lean mass as a surrogate for muscle mass. We postulate that inaccurate measures of muscle mass may have obscured the role of obesity in sarcopenia and related outcomes. Our aim was to clarify the interactions of muscle and fat with physical performance and adverse outcomes using an accurate measure of muscle mass. Methods: In a longitudinal study of >1,300 older men (mean age 84 years), we compared a direct measurement of muscle mass (D3 creatine dilution; D3Cr) with an approximation of muscle mass (appendicular lean mass [ALM] by dual-energy x-ray absorptiometry [DXA]) and their associations with measures of physical performance (gait speed, chair stand time) and adverse outcomes (incident injurious falls and mobility problems). We measured percent fat mass by DXA. Results: Low D3Cr muscle mass was strongly associated with decreased performance and increased risk of adverse outcomes. Increased fat mass had little association after accounting for D3Cr muscle mass. In contrast, DXA ALM was minimally associated with performance or adverse outcomes, and fatness remained associated with both outcomes after accounting for DXA ALM. Conclusions: When an accurate assessment of muscle mass (rather than lean mass) is used, reduced muscle mass is highly associated with important outcomes and the negative effects of adiposity are minimal, suggesting that obesity has little relevance for the understanding of important adverse health outcomes of sarcopenia in older men.
KW - Aging
KW - Disability
KW - Sarcopenia
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U2 - 10.1093/gerona/glaa064
DO - 10.1093/gerona/glaa064
M3 - Article
C2 - 32436565
AN - SCOPUS:85086748445
SN - 1079-5006
VL - 75
SP - 1362
EP - 1368
JO - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
JF - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
IS - 7
ER -