Lean mass, muscle strength, and physical function in a diverse population of men: a population-based cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Age-related declines in lean body mass appear to be more rapid in men than in women but our understanding of muscle mass and function among different subgroups of men and their changes with age is quite limited. The objective of this analysis is to examine racial/ethnic differences and racial/ethnic group-specific cross-sectional age differences in measures of muscle mass, muscle strength, and physical function among men.</p> <p>Methods</p> <p>Data were obtained from the Boston Area Community Health/Bone (BACH/Bone) Survey, a population-based, cross-sectional, observational survey. Subjects included 1,157 black, Hispanic, and white randomly-selected Boston men ages 30-79 y. Lean mass was assessed by dual-energy x-ray absorptiometry. Upper extremity (grip) strength was assessed with a hand dynamometer and lower extremity physical function was derived from walk and chair stand tests. Upper extremity strength and lower extremity physical function were also indexed by lean mass and lean mass was indexed by the square of height.</p> <p>Results</p> <p>Mean age of the sample was 47.5 y. Substantial cross-sectional age differences in grip strength and physical function were consistent across race/ethnicity. Racial/ethnic differences, with and without adjustment for covariates, were evident in all outcomes except grip strength. Racial differences in lean mass did not translate into parallel differences in physical function. For instance, multivariate modeling (with adjustments for age, height, fat mass, self-rated health and physical activity) indicated that whereas total body lean mass was 2.43 kg (approximately 5%) higher in black compared with white men, black men had a physical function score that was approximately 20% lower than white men.</p> <p>Conclusions</p> <p>In spite of lower levels of lean mass, the higher levels of physical function observed among white compared with non-white men in this study appear to be broadly consistent with known racial/ethnic differences in outcomes.</p

Non-invasive assessment of left ventricular longitudinal impedance using color M-mode Doppler echocardiography

We hypothesised that a measured mitral valve diameter and a color Doppler M-mode image of left ventricular inflow provide sufficient information for the non-invasive estimation of the left ventricular longitudinal impedance of left ventricular filling. The aim of this study was therefore (I) to develop the algorithms for calculation of left ventricular longitudinal impedance from a color Doppler M-mode image and (2) to study the feasibility of this calculation In an in vitro experiment. In a cardiovascular simulator consisting of a left ventricular pulse duplicator system connected to a hydraulic model of the arterial tree, color M-mode images of left ventricular inflow were captured. Pressure differences are calculated by implementing the Euler equation. Velocity at the level of the mitral valve is used for the calculation of flow. Pressure gradients and flow are used for calculation of the longitudinal impedance in the frequency domain. No influence on the amplitude of the calculated longitudinal impedance was observed (p>0.05) for a change in heart rate and systolic pressure. However, the calculated longitudinal impedance was significantly altered for a smaller valve and a different test fluid (p<0.05). In conclusion, longitudinal impedance of left ventricular inflow can be derived non-invasively from color Doppler M-mode images and provides a quantitative interpretation of the numerical velocity information in a color Doppler M-mode image with potential clinical useful information

Assessment of the time constant of relaxation: insights from simulations and hemodynamic measurements.

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