scholarly journals Proof of the effect of testosterone on skeletal muscle

2001 ◽  
Vol 170 (1) ◽  
pp. 27-38 ◽  
Author(s):  
S Bhasin ◽  
L Woodhouse ◽  
TW Storer
Keyword(s):  
Physical Function ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Older Men ◽  
Fat Free Mass ◽  
Testosterone Replacement ◽  
Dependent Manner ◽  
Improve Performance ◽  
Low Testosterone

In spite of the widespread abuse of androgenic steroids by athletes and recreational body-builders, the effects of these agents on athletic performance and physical function remain poorly understood. Experimentally induced androgen deficiency is associated with a loss of fat-free mass; conversely, physiologic testosterone replacement of healthy, androgen-deficient men increases fat-free mass and muscle protein synthesis. Testosterone supplementation of HIV-infected men with low testosterone levels and of older men with normally low testosterone concentrations also increases muscle mass. However, we do not know whether physiologic testosterone replacement can improve physical function and health-related quality of life, and reduce the risk of falls and disability in older men or those with chronic illness. Testosterone increases maximal voluntary strength in a dose-dependent manner and thus might improve performance in power-lifting events. However, testosterone has not been shown to improve performance in endurance events. The mechanisms by which testosterone increases muscle mass are not known, but probably involve alterations in the expression of multiple muscle growth regulators.

scholarly journals Association of Protein Intake in Three Meals with Muscle Mass in Healthy Young Subjects: A Cross-Sectional Study

Nutrients ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 612 ◽  
Author(s):  
Jun Yasuda ◽  
Mai Asako ◽  
Takuma Arimitsu ◽  
Satoshi Fujita
Keyword(s):  
Muscle Mass ◽  
Protein Intake ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Cross Sectional Study ◽  
Fat Free Mass ◽  
Intake Rate ◽  
Young Population ◽  
Cross Sectional ◽  
Young Subjects

Protein intake of >0.24 g/kg of body weight (BW) at a single meal is necessary to maximize muscle protein synthesis in a young population. However, the association between the protein intake rate for three meals and muscle mass in the young population has not been evaluated. We hypothesized that a protein intake of >0.24 g/kg BW at all three meals is effective for maintaining muscle mass. Therefore, we cross-sectionally examined the association between protein intake at all three meals with muscle mass in 266 healthy young subjects (aged 21.4 ± 2.4 years). Subjects were divided into the AP group, which achieved protein intake >0.24 g/kg BW at all three meals; and the NP group, which did not. We calculated total fat-free mass (FFM) and appendicular fat-free mass (AppFFM) with dual-energy X-ray absorptiometry, and the percentage of total FFM (TotalFFM%) and appendicular FFM (AppFFM%) were calculated as the percentage of BW (%BW). We demonstrated that TotalFFM% (77.0 ± 0.5 vs. 75.2 ± 0.4%, p = 0.008) and AppFFM% (34.7 ± 0.3 vs. 34.1 ± 0.2%, p = 0.058) were higher in the AP than in the NP group. This finding suggests that achieving protein intake of >0.24 g/kg BW at all three meals is important for muscle mass maintenance in young populations.

scholarly journals Supplementing Breakfast with a Vitamin D and Leucine–Enriched Whey Protein Medical Nutrition Drink Enhances Postprandial Muscle Protein Synthesis and Muscle Mass in Healthy Older Men

2017 ◽  
Vol 147 (12) ◽  
pp. 2262-2271 ◽  
Author(s):  
Audrey Chanet ◽  
Sjors Verlaan ◽  
Jérôme Salles ◽  
Christophe Giraudet ◽  
Véronique Patrac ◽  
...  
Keyword(s):  
Vitamin D ◽  
Protein Synthesis ◽  
Whey Protein ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Older Men ◽  
Medical Nutrition

scholarly journals Hormone Replacement Therapy and Physical Function in Healthy Older Men. Time to Talk Hormones?

2012 ◽  
Vol 33 (3) ◽  
pp. 314-377 ◽  
Author(s):  
Manthos G. Giannoulis ◽  
Finbarr C. Martin ◽  
K. Sreekumaran Nair ◽  
A. Margot Umpleby ◽  
Peter Sonksen
Keyword(s):  
Hormone Replacement Therapy ◽  
Physical Function ◽  
Replacement Therapy ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Hormone Replacement ◽  
Older Men ◽  
Muscle Adaptation ◽  
Igf I

Improving physical function and mobility in a continuously expanding elderly population emerges as a high priority of medicine today. Muscle mass, strength/power, and maximal exercise capacity are major determinants of physical function, and all decline with aging. This contributes to the incidence of frailty and disability observed in older men. Furthermore, it facilitates the accumulation of body fat and development of insulin resistance. Muscle adaptation to exercise is strongly influenced by anabolic endocrine hormones and local load-sensitive autocrine/paracrine growth factors. GH, IGF-I, and testosterone (T) are directly involved in muscle adaptation to exercise because they promote muscle protein synthesis, whereas T and locally expressed IGF-I have been reported to activate muscle stem cells. Although exercise programs improve physical function, in the long-term most older men fail to comply. The GH/IGF-I axis and T levels decline markedly with aging, whereas accumulating evidence supports their indispensable role in maintaining physical function integrity. Several studies have reported that the administration of T improves lean body mass and maximal voluntary strength in healthy older men. On the other hand, most studies have shown that administration of GH alone failed to improve muscle strength despite amelioration of the detrimental somatic changes of aging. Both GH and T are anabolic agents that promote muscle protein synthesis and hypertrophy but work through separate mechanisms, and the combined administration of GH and T, albeit in only a few studies, has resulted in greater efficacy than either hormone alone. Although it is clear that this combined approach is effective, this review concludes that further studies are needed to assess the long-term efficacy and safety of combined hormone replacement therapy in older men before the medical rationale of prescribing hormone replacement therapy for combating the sarcopenia of aging can be established.

scholarly journals Effects of Fortetropin on the Rate of Muscle Protein Synthesis in Older Men and Women: A Randomized, Double-Blinded, Placebo-Controlled Study

2020 ◽  
Vol 76 (1) ◽  
pp. 108-114
Author(s):  
William Evans ◽  
Mahalakshmi Shankaran ◽  
Edna Nyangau ◽  
Tyler Field ◽  
Hussein Mohammed ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Egg Yolk ◽  
Older Men ◽  
Controlled Study ◽  
Lipid Complex ◽  
Gene Ontologies

Abstract Background Fortetropin is a proteo-lipid complex made from fertilized egg yolk and, in young men, has been shown to increase lean body mass. Methods The purpose of this study was to examine the effects of 21 days of Fortetropin supplementation on the fractional synthetic rate (FSR) of muscle protein in 10 healthy, older men and 10 women (66.4 ± 4.5 y). We used 2H2O labeling to measure FSR of multiple muscle protein ontologies. D3-creatine dilution was used to determine muscle mass at baseline. Subjects ingested 70% 2H2O for 21 day and saliva samples were collected to determine body 2H2O enrichment. A microbiopsy was obtained from the m. vastus lateralis on Day 21. Subjects were randomly assigned to Fortetropin (19.8 g/d) or placebo (cheese powder, 19.8 g/d). Results Restricting kinetic data to proteins with ≥2 peptides measured in at least 4 subjects per group resulted in 117 proteins meeting these criteria. The mean FSR for a majority of proteins in several muscle gene ontologies was higher in the Fortetropin group compared to placebo (32/38 myofibril proteins, 33/44 sarcoplasmic proteins, and 12/17 mitochondrial proteins) and this proportion was significantly different between groups using a binomial test and were independent of sex or baseline muscle mass. Conclusions The overall magnitude of the difference in muscle protein FSR of Fortetropin from placebo was 18%, with multiple gene ontologies affected. While these results should be confirmed in larger cohorts, they suggest that Fortetropin supplementation is effective for promoting muscle protein synthesis in older people.

Side Effects of Creatine Supplementation in Athletes

2006 ◽  
Vol 1 (4) ◽  
pp. 311-323 ◽  
Author(s):  
Marc Francaux ◽  
Jacques R. Poortmans
Keyword(s):  
Protein Synthesis ◽  
Side Effects ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Creatine Supplementation ◽  
Indirect Evidence ◽  
Fat Free Mass ◽  
Scientific Publications ◽  
Heavy Load

Context:Allegations about side effects of creatine supplementation by athletes have been published in the popular media and scientific publications.Purpose:To examine the experimental evidence relating to the physiological effects of creatine supplementation.Results:One of the purported effects of oral creatine supplementation is increased muscle mass. A review of the literature reveals a 1.0% to 2.3% increase in body mass, which is attributed to fat-free mass and, more specifically, to skeletal-muscle mass. Although it is unlikely that water retention can completely explain these changes, increase in muscle-protein synthesis has never been observed after creatine supplementation. Indirect evidence based on mRNA analyses suggests that transcription of certain genes is enhanced. Although the effect of creatine on muscle-protein synthesis seems irrefutable according to advertising, this allegation remains under debate in the scientific literature. The kidneys appear to maintain their functionality in healthy subjects who supplement with creatine, even over several months.Conclusion:The authors, however, think that creatine supplementation should not be used by an individual with preexisting renal disease and that risk should be evaluated before and during any supplementation period. Even if there is a slight increase in mutagenic agents (methylamine and formaldehyde) in urine after a heavy load of creatine (20 g/day), their excretion remains within a normal range. No data are currently available regarding the potential production of heterocyclic amines with creatine supplementation. In summary, the major risk for health is probably associated with the purity of commercially available creatine.

Whey protein supplementation in muscle hypertrophy

2020 ◽  
Vol 30 (Supplement_2) ◽  
Author(s):  
C Sobral ◽  
D Gomes ◽  
M Silva ◽  
P Martins ◽  
A Baltazar
Keyword(s):  
Whey Protein ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Amino Acid Content ◽  
Protein Supplementation ◽  
Fat Free Mass ◽  
Control Group ◽  
Potential Health ◽  
Experimental Group

Abstract Introduction The nutritional intake in the context of a hypertrophy training can affect body composition, the increase of muscle mass and strength. Whey protein seems to promote a reduction in body fat, improve hypertrophy, and other potential health benefits. This protein is one of the highest quality proteins due to its amino acid content (especially leucine) and to the rapid digestibility. Whey protein consumption has a robust ability to stimulate muscle protein synthesis. There are 3 types of whey protein: controlled, insulated and hydrolysed. Objectives The goal of this research is verifying the efficacy of the use of whey protein supplementation in athletes seeking muscle strength and mass gain. Methodology * We analysed scientific articles from 2014 to 2019, based on Pubmed and Google scholar. Keywords such as whey protein, supplement, hypertrophy, muscle mass and nutrition were used. Results From scientific research, six articles were analysed. Thus, it is estimated the analysis of 13 men under the age of 18 years and under 30 years of age. Only men with a percentage of fat mass less than or equal to 23% were selected. Two groups were created: the control group that consumed carbohydrate supplements and the experimental group that consumed 36g/day whey protein. Both groups performed 3 sessions/week of resistance training, and the used dose of protein derived from the diet was 1.4g/Kg/day. Both groups experienced gains in strength, 1 maxi (RM) and fat-free mass (FFM). However, the experimental group had an extra 9% and 27% in 1RM and FFM respectively compared to the control group. Conclusion In short, supplementation with whey protein contributes to the increase of muscle mass and strength in athletes whose training (frequency, volume and duration) and diet are suitable for this purpose.

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