Muscle mass

A muscle mass normalized for height2 (MMI) or for body weight (SMI) below 2SD under the mean for a young population defines sarcopenia. This study aimed at setting the cutoffs and the prevalence of sarcopenia in the French elderly population. Another objective was to compare the results obtained with SMI and MMI. Muscle mass was assessed by bioelectrical impedance analysis in 782 healthy adults (< 40 years) to determine skeletal mass index (SMI, muscle mass*100/weight) and muscle mass index (MMI, muscle mass/height2). Prevalence was estimated in 888 middle aged (40-59 years) and 218 seniors (60-78 years). All were healthy people. For women mean-2SD were 6.2 kg/m2 (MMI) and 26.6% (SMI); for men limits were 8.6 kg/m2 (MMI) and 34.4% (SMI). In middle aged persons a small number of them were identified as sarcopenic. In healthy seniors, 2.8% of women and 3.6% of men were sarcopenic (MMI). The prevalence was 23.6% in women and 12.5% in men with SMI. MMI and SMI identified different sa...

Men generally have an inherent performance advantage over women due to their average greater height and muscle mass and power, as the result of correspondingly different exposures to androgens. Therefore, it is considered fair that in sports men and women compete in separate categories. The question now emerging is whether reassigned transsexuals can compete in fairness with others of their new sex. The pertinent question is how far the previous effects of testosterone in male-to-female transsexuals (M-F) are reversible upon androgen deprivation so that M-F have no advantage over women, and, vice versa, what the effects are of androgen exposure in female-to-male transsexuals (F-M) on variables relevant to competition in sports. Before puberty, boys and girls do not differ in height, muscle and bone mass. Recent information shows convincingly that actual levels of circulating testosterone determine largely muscle mass and strength, though with considerable interindividual diversity. ...

Background. To review currently available evidence on the effect of cow-milk proteins supplementation (CPS) on health in the elderly. Methods. Five electronic databases (Pubmed, Web of Science, Embase, Cochrane Library, ClinicalTrials.gov) were searched for studies about CPS among older people. All types of publications were included, with the exception of systematic reviews, meta-analyses, opinion letters, editorials, case reports, conference abstracts and comments. An additional search in Google Scholar and a manual review of the reference lists were performed. Results. Overall, 103 studies were included. Several studies explored the role of CPS in the preservation or improvement of muscle mass among healthy subjects (40 studies) and pre-frail, frail or sarcopenic patients (14), with evidence of beneficial effects. Other studies assessed the effect of CPS on bones (12), cardiovascular disease (8), inflamm-aging (7), chronic pulmonary disease (4), neurocognitive function (4), and v...

Medical nutrition therapy plays a major role in diabetes management. Macronutrient composition has been debated for a long time. However, there is increasing evidence that a modest increase in dietary protein intake above the current recommendation is a valid option toward better diabetes control, weight reduction, and improvement in blood pressure, lipid profile, and markers of inflammation. Increasing the absolute protein intake to 1.5-2 g/kg (or 20-30% of total caloric intake) during weight reduction has been suggested for overweight and obese patients with type 2 diabetes and normal kidney function. Increased protein intake does not increase plasma glucose, but increases the insulin response and results in a significant reduction in hemoglobin A(1c). In addition, a higher dietary protein intake reduces hunger, improves satiety, increases thermogenesis, and limits lean muscle mass loss during weight reduction using a reduced calorie diet and increased physical activity. It is pre...

The aim of this systematic review was to determine if eccentric exercise is superior to concentric exercise in stimulating gains in muscle strength and mass. Meta-analyses were performed for comparisons between eccentric and concentric training as means to improve muscle strength and mass. In order to determine the importance of different parameters of training, subgroup analyses of intensity of exercise, velocity of movement and mode of contraction were also performed. Twenty randomised controlled trials studies met the inclusion criteria. Meta-analyses showed that when eccentric exercise was performed at higher intensities compared with concentric training, total strength and eccentric strength increased more significantly. However, compared with concentric training, strength gains after eccentric training appeared more specific in terms of velocity and mode of contraction. Eccentric training performed at high intensities was shown to be more effective in promoting increases in muscle mass measured as muscle girth. In addition, eccentric training also showed a trend towards increased muscle cross-sectional area measured with magnetic resonance imaging or computerised tomography. Subgroup analyses suggest that the superiority of eccentric training to increase muscle strength and mass appears to be related to the higher loads developed during eccentric contractions. The specialised neural pattern of eccentric actions possibly explains the high specificity of strength gains after eccentric training. Further research is required to investigate the underlying mechanisms of this specificity and its functional significance in terms of transferability of strength gains to more complex human movements.

The objective of this study was to determine the effect of creatine supplementation on performance and body composition of swimmers. Eighteen swimmers were evaluated in terms of post-performance lactate accumulation, body composition, creatine and creatinine excretion, and serum creatinine concentrations before and after creatine or placebo supplementation. No significant differences were observed in the marks obtained in swimming tests after supplementation, although lactate concentrations were higher in placebo group during this period. In the creatine-supplemented group, urinary creatine, creatinine, and body mass, lean mass and body water were significantly increased, but no significant difference in muscle or bone mass was observed. These results suggest that creatine supplementation cannot be considered to be an ergogenic supplement ensuring improved performance and muscle mass gain in swimmers.