Combating Age-Related Muscle Loss and Strength
Similar to the rest of the world, the United States is an aging society. Between the years 2000 and 2050, the aging population is projected to increase by 135% with over 100 million adults in the US over age 50 (1). With increased age, there are many unwanted changes to the human body. One such change is sarcopenia, which is defined as the loss of skeletal muscle mass and strength, with muscle atrophy beginning at age 25 (2). Muscle is essential for maintaining muscle action, functional independence, managing daily activities, and living a healthy active lifestyle (3). Inactive adults experience a 3% to 8% loss of muscle mass per decade, accompanied by a lower resting metabolic rate, fat accumulation, and weight gain. Evidence also shows that strength declines at a greater rate than the loss of muscle of about 12-15% per decade after the fifth decade of life (4).
There are several interventions that can help prevent the loss of skeletal muscle mass and strength associated with age, with resistance training, increased protein intake, and creatine supplementation being an important part of this process. Resistance training has the ability to decrease fat mass, as well as the ability to increase lean body mass, metabolism, and strength. In addition, resistance training has shown to increase bone mineral density by as much as 1-3%, improve cardiovascular health by reducing resting blood pressure and cholesterol levels, along with improving cognitive abilities, glucose levels, and prevention of type 2 diabetes (5,6). Nutritionally, there is substantial evidence that supports the consumption of high-quality protein well above the current Recommended Dietary Allowance (RDA) to achieve optimal health outcomes to promote healthy aging, increased muscle mass and strength, appetite regulation, and weight management. This current evidence suggests intakes in the range of at least 1.2 to 1.6 g/kg per day of high quality protein to achieve optimal health outcomes for active adults, compared to the current RDA Guidelines for protein of 0.8 g/kg per day for all adults including older ones (7).
It is important to note that the recommendations for increased protein consumption are based upon studies that include high quality, animal-based proteins that include lean animal sources that allow for the greatest protein content with fewer calories. In addition, with data being somewhat limited, there is increasing evidence that animal proteins, such as whey protein that contains the branched-chain amino acid leucine, promotes gains in lean mass through increased muscle protein synthesis and improve appetite control and satiety more so than some plant proteins (8). Pre- and post-exercise protein supplementation via a protein shake can be effective to promote muscle anabolism. This additional protein should ideally be met through a balanced diet, and supplementation could be considered when protein intake from dietary sources is insufficient to meet the increased protein needs associated with resistance training (9). Creatine is a nutritional supplement that has been reported to be a safe ergogenic aid in healthy adults (10). Several studies have shown when creatine supplementation is used in combination with resistance training there was an increase in lean tissue mass and muscle strength in aging adults. In addition, creatine supplementation may show promise for improving bone mineral density (11,12).
In conclusion, it has been shown that age-related muscle loss and strength could impact functional independence, along with living an active, healthy lifestyle. Age-related muscle loss might contribute to health related concerns such as weight gain, cardiovascular diseases, metabolic diseases, and bone loss. Resistance training, increased protein intake, and creatine supplementation in combination with resistance training has shown to be viable interventions for the aging population in the prevention of muscle loss and strength. It must be noted that these recommendations are for healthy adults with proper medical clearance and advice for dosing and administration.
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