Dataset Information

Muscle Quality, Strength, and Lower Extremity Physical Performance in the Baltimore Longitudinal Study of Aging.

ABSTRACT: BACKGROUND:Muscle quality is defined as the force generated by each volumetric unit of muscle tissue. No consensus exists on an optimal measure of muscle quality, impeding comparison across studies and implementation in clinical settings. It is unknown whether muscle quality measures that rely on complex and expensive tests, such as isokinetic dynamometry and computerized tomography correlate with lower extremity performance (LEP) any better than measures derived from simpler and less expensive tests, such as grip strength (Grip) and appendicular lean mass (ALM) assessed by DXA. Additionally, whether muscle quality is more strongly associated with LEP than strength has not been fully tested. OBJECTIVES:This study compares the concurrent validity of alternative measures of muscle quality and characterizes their relationship with LEP. We also whether muscle quality correlates more strongly with LEP than strength alone. DESIGN:Cross-sectional analysis. SETTING:Community. PARTICIPANTS:365 men and 345 women 65 years of age and older in the Baltimore Longitudinal Study of Aging. MEASURES:Thigh cross-sectional area (TCSA), isokinetic and isometric knee extension strength (ID), BMI adjusted ALM (ALMBMI) from DXA, and Grip. Concurrent validity was assessed as the percent variance of different measures of LEP explained by each muscle quality measure. In addition, we compared LEP relationships between each measure of strength and its correspondent value of muscle quality. Confidence intervals for differences in percent variance were calculated by bootstrapping. RESULTS:Grip/ALMBMI explained as much variance as ID/TCSA across all LEP measures in women and most in men. Across all LEP measures, strength explained as much variance of LEP as muscle quality. CONCLUSIONS:Grip/ALMBMI and ID/TCSA measures had similar correlations with LEP. Muscle quality did not outperform strength. Although evaluating muscle quality may be useful to assess age-related mechanisms of change in muscle strength, measures of strength alone may suffice to understand the relationship between muscle and LEP.

SUBMITTER: Chiles Shaffer N

PROVIDER: S-EPMC6232847 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Muscle Quality, Strength, and Lower Extremity Physical Performance in the Baltimore Longitudinal Study of Aging.

Chiles Shaffer N N Fabbri E E Ferrucci L L Shardell M M Simonsick E M EM Studenski S S

The Journal of frailty & aging 20170101 4

<h4>Background</h4>Muscle quality is defined as the force generated by each volumetric unit of muscle tissue. No consensus exists on an optimal measure of muscle quality, impeding comparison across studies and implementation in clinical settings. It is unknown whether muscle quality measures that rely on complex and expensive tests, such as isokinetic dynamometry and computerized tomography correlate with lower extremity performance (LEP) any better than measures derived from simpler and less ex ...[more]

PMID: 29165533

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Project description:ObjectivePersons with diabetes have accelerated muscle loss compared with their counterparts. The relationship of hyperglycemia per se to declines in muscle function has not been explored yet has implications for developing appropriate intervention strategies to prevent muscle loss.Research design and methodsWe examined 984 participants aged 25-96 years in the Baltimore Longitudinal Study of Aging (2003-2011) with HbA1c, knee extensor strength (isokinetic dynamometer), and lean body mass (DEXA) measured at baseline. Participants had repeated measurements up to 7.5 years later. Muscle quality was defined as knee extensor strength/leg lean mass. Participants were categorized by HbA1c quartile (<5.5, 5.5-5.79, 5.8-6.09, and ?6.1% or <37, 37-40, 40-43, and ?43 mmol/mol). Mixed-effects regression models were used to examine the regression of muscle outcomes on HbA1c.ResultsMuscle strength and quality were significantly lower across HbA1c quartiles (both P < 0.001), without differences in muscle mass at baseline. Comparing highest versus lowest HbA1c quartiles and adjusting for age, race, sex, weight, and height, strength was significantly lower (-4.70 ± 2.30 N · m; P value trend = 0.02) and results were unchanged after adjustment for physical activity (P value trend = 0.045) but of borderline significance after additional adjustment for peripheral neuropathy (P value trend = 0.05). Adjusting for demographics, muscle quality was significantly lower (-0.32 ± 0.15 N · m/kg; P value trend = 0.02) in the highest versus lowest HbA1c quartiles, but differences were attenuated after adjusting for weight and height (-0.25 ± 0.15 N · m/kg; P value trend = 0.07). Muscle mass measures were similar across HbA1c quartiles.ConclusionsHyperglycemia is associated with persistently lower muscle strength with aging, but this effect may be mediated, at least in part, by peripheral neuropathy. Future studies should explore if better glycemic control can preserve muscle function in diabetes.

Dataset Information

Muscle Quality, Strength, and Lower Extremity Physical Performance in the Baltimore Longitudinal Study of Aging.

Publications

Muscle Quality, Strength, and Lower Extremity Physical Performance in the Baltimore Longitudinal Study of Aging.

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