Between the fourth and fifth decade of life, a human can experience the potential effects of sarcopenia – the aging loss of muscle, and its associated dynapenia – the deterioration of strength and power.
It estimated, according to a study - Nutritional Supplements to Support Resistance Exercise in Countering the Sarcopenia of Aging - which appeared in the August 2020 issue of the online journal Nutrients, that from 2.5 to 30 % of older adults are categorized, as having low muscle mass.
Additionally, “the progression of sarcopenia is closely associated with (the) enhanced risk of falls and fractures, metabolic dysfunction, cardiac and respiratory disease development, early mortality, and overall quality of life. Thus, age-related skeletal muscle deterioration warrants significant trepidation,” commented the nutrient authors from the Exercise Metabolism Research group, Department of Kinesiology, McMasters University, Hamilton, Ontario, Canada.
As any body builders knows, lean muscle development is a balance between muscle protein synthesis (MPS) - also called anabolism and muscle protein breakdown (MPB) – known as catabolism, while attempting to stay in what’s called positive nitrogen balance from diet - specifically protein intake, resistive exercise (RE), and nutritional supplement support.
The Canadian researchers sought to provide an up-to-date discussion surrounding the interaction between RE and various nutritional strategies, as a means to augment MPS, promote muscle protein accumulation, and mitigate the progression of sarcopenia.
It’s known that RE reduces the risk to type 2 diabetes, cardiovascular disease, and cancer, but RE also is the primary means to counter the age-associated effects of sarcopenia and dynapenia.
The Canadians note that, “at the molecular level, a bout of RE stimulates MPS via activation of the mechanistic target of rapamycin (mTORC-1) signaling pathway,” which increases protein synthesis and lean muscle development.
With age, there is a loss of type II muscle fibers - creating the dynapenia effect. It’s reported that the vastus lateralis (thigh muscle) accounts for approximately 30% of quadriceps muscle mass – yielding an estimates 20,000 individual muscle fibers to be lost from each quadricep muscle per year, beyond the age of 30 years (assuming a linear decline). If ignored, by failing to perform RE, then said fiber loss will have marked consequences for muscular strength, power, and the maintenance of muscular functional capacity.
The Canadians report on current research, which states that, “work-matched studies in younger and older adults have demonstrated that low-load RT (i.e., 30–50% 1-repetition maximum) may be just as effective as high-load RT to increase muscle mass and strength, when performed to volitional fatigue,” - practically translated, an exertion of a high degree of effort.
From a protein feeding standpoint, the recommended daily dietary allowance (RDA) of 0.8 grams of protein per kilogram to maintain nitrogen balance has been unchanged for decades – warranting further scrutiny, as it pertains to older adults, who have increased protein requirements.
The Canadians site the PROT-AGE study group and the European Society for Clinical Nutrition and Metabolism, which have, “suggested that older adults should consume between 1.0–1.5 g/kg/day of protein” – commenting that current protein recommendations are yet to be revised.
As to the allocation of the effective protein dosage per meal or from a supplementary standpoint, research has demonstrated that, “feeding-induced MPS is saturated following ingestion of ~0.24 g protein/kg/meal and 0.4 g protein/kg/meal in younger and older adults, respectively.”
It was also stated that, a protein intake pattern that is more evenly distributed throughout the day may help confer significant musculoskeletal benefits.
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