MUSCLE MASS, STRENGTH, AND OPTIMIZING HEALTHSPAN
As we age our body composition gradually shifts to include more fat and less lean body mass. This age-related loss of muscle mass and strength is called sarcopenia. After age 30, you lose up to 5% of your muscle mass per decade and up about 50% over your lifetime (1). Muscle strength declines more rapidly at up to 2% per year (2).
Sarcopenia is associated with increased risk of metabolic impairment, cardiovascular disease, fatigue, falls, and mortality. In elderly people, muscle loss correlates with decreased quality of life and the loss of ability to independently perform activities of daily living. The common coexistence of diminished lean mass and increased fat mass is called sarcopenic obesity. This predicts an even higher rate functional impairment as diminished muscle strength attempts to support a greater mechanical load (3).
A 2019 study of older adults in the Journal of Bone and Mineral Research showed that increased visceral fat and reduced lean muscle mass are strong independent predictors of mortality. Over a mean follow‐up of 4 years, men with low muscle mass in their arms and legs had an 11 fold increased risk in all-cause mortality and women with low muscle mass in their arms and legs were even more likely to die early (4). This further supports the existing body of literature linking lean body mass to mortality (5-7).
Muscle Strength and Mortality
Muscular strength is also significantly and inversely associated with risk of death from all causes after controlling for potential confounders including cardiorespiratory fitness. In a study of about 8000 people aged 20-80 that tested upper and lower body strength, the inverse association was consistent for people <60 and ≥60 years and with a body mass index above and below 25 kg/m2. All cause mortality rates were 1.5 times greater for those in the lowest third of muscular strength than for those in the middle and upper thirds of muscular strength (8). A significant inverse association between muscular strength measured by handgrip strength and risk of mortality has been reported in several other studies (9). Of note, optimal muscle strength and cardio-respiratory function likely provides the greatest benefits. In a study that evaluated both muscle strength and heart/lung fitness, age adjusted death rate in people with high levels of both muscular strength and cardiorespiratory fitness was 60% lower than the death rate in the group of unfit men with the lowest levels of muscular strength (8).
How To Build Muscle Mass
Our bodies are continually synthesizing and degrading muscle 24/7. The two things that favor muscle synthesis are the steady consumption of protein and exercise. In regards to protein, aim to consume at least 0.5g of protein per pound of body mass divided over 3-4 meals. Exercise should include at least 2 thirty-minute sessions of resistance training per week. Athletes attempting to maximize muscle mass may consume up to a gram of protein per pound of lean body mass and increase their resistance training up to 4 hours per week. Also keep in mind that you can achieve similar gains with moderate-intensity resistance training (done with weights, bands, or bodyweight) versus high intensity training to failure. Particularly for people >40 moderate intensity training is also less likely to cause injury.
Maybe most importantly, appreciate that sarcopenia isn’t inevitable, and can even be reversed by optimal nutrition and resistance training. While it is best to engage in consistent resistance training throughout your life, it is possible to build muscle at any age (2,10).
Bradford Rabin MD
Our concierge medicine practice focuses on exercise, nutrition, and longevity medicine to provide the best primary care concierge medicine. Primary care concierge medicine practices take care of smaller groups of patients and have the bandwidth to focus on the individual drivers for healthspan with personalized exercise and nutrition plans.
1 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4066461/
2 https://journals.physiology.org/doi/full/10.1152/japplphysiol.90332.2008
3 https://pubmed.ncbi.nlm.nih.gov/18615231/
4 https://asbmr.onlinelibrary.wiley.com/doi/pdf/10.1002/jbmr.3710
5 https://pubmed.ncbi.nlm.nih.gov/27126709/
6 https://pubmed.ncbi.nlm.nih.gov/21288234/
7 https://pubmed.ncbi.nlm.nih.gov/20237137/
8 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2453303/?_escaped_fragment_=po=42.5000
10 https://www.nature.com/articles/s41598-019-44329-6
Visit our website : https://bradfordrabinmd.com/