Indicators of Absolute and Relative Changes in Skeletal Muscle Mass during Adulthood and Ageing

Abstract

This study aimed to explore the set of variables related to skeletal muscle mass (SMM) in both sexes, and to create age- and sex-related models of changes in SMM, using the most representative indicator of muscular status. Body composition was assessed in 8733 subjects (♀ = 3370 and ♂ = 5363), allocated into subsamples according to age: 18–29.9, 30–39.9, 40–49.9, 50–59.9, 60–69.9, and 70.0–79.9 years. Nine variables were used: protein mass, protein percent, protein mass index, SMM, percent of SMM, SMM index, fat-free mass, fat-free mass index, and protein/fat index. Univariate and multivariate analysis of variance (ANOVA and MANOVA) were used to determine between- and within-sex difference in all variables by age. Correlation analysis established the relationship between age and muscularity variables. Principal Component Analysis extracted the variables that loaded highest in explaining muscularity, while regression analysis determined the linearity of association between the age and indicators of muscular status. Variables SMMI and PSMM were extracted as the most sensitive to age, with SMMI being gender-independent while showing the parabolic and sinusoidal form of change as function of ageing in males and females, respectively; and PSMM being sex-dependent while showing a linear trend of decrease in both sexes.

Sarcopenia, Exercise and Quality of Life

“…This translates into an increased risk of poor quality of life, physical disability, frequent falls and weakness, and death. In this sense, four manuscripts [ 3 , 8 , 9 , 11 ] in this special issue, corresponding to 33.3% of the total, corroborate that muscle loss is the typical consequence of all older adults. The study by Patiño-Villada et al [ 8 ] considers the combination of high muscle mass and shallow fat mass a highly healthy variety.…”

“…This special edition of the Journal of Environmental Research and Public Health ( IJERPH ) has brought together eleven research manuscripts [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ] and a brief report [ 12 ]. This special issue, entitled “ Sarcopenia, Exercise and Quality of Life ” gathered 12 manuscripts [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]; four (33.3%) manuscripts are related to the impact of physical activity concerning sarcopenia [ 4 , 6 , 7 , 10 ]. Two manuscripts were used for the Wii Fit ® games as an intervention tool for physical activity in institutionalized elderly patients [ 4 , 6 ].…”

“…This suggests that diagnostic imaging techniques are more advantageous than molecular biology analytical determinations. Dopsaj et al [ 3 ] evaluated muscle components by measuring different body composition variables. Among these variables body, skeletal muscle mass index (SMMI; kg/m 2 ) and percentage of skeletal muscle mass (PSMM; %) are the most sensitive to age.…”

“…Still, it is necessary to also consider body fat mass. Thus, these authors [ 3 ] consider body fat plus muscle mass assessment essential in the description of the sarcopenic patient. Also, muscle rehabilitation work of the lower limbs (quadriceps and hamstrings) is vital to increasing muscle mass.…”

Body Composition in International Sprint Swimmers: Are There Any Relations with Performance?

“…All participants were measured in accordance with manufacturer’s suggestions and previously published procedures [ 7 , 8 , 27 , 29 ].…”