Muscle Mass and Longevity: Lifting Weights to Live Longer

Numerous studies underscore the role of lean body mass, particularly skeletal muscle tissue, in extending life expectancy [1]. But strength training (e.g. lifting weights) does much more than help you live longer. Research has shown that resistance training can improve heart health/cardiovascular function, reduce the risk of sarcopenia (age-related muscle loss), and even strengthen joints (as counterintuitive as that may seem) [2].

In this article, we'll focus mainly on the ties between muscle mass and longevity but not so much on "how to build muscle." However, we have covered topics related to muscle-building nutrition and exercise strategies at length in previous blogs, so there will be links to some of those resources throughout this piece.

The Importance of Muscle Mass in Aging

Meta-analyses of aging cohorts show a strong inverse correlation between skeletal muscle mass index and the risk of all-cause mortality (read: death of any cause) [3, 4]. In other words, these studies have found that people with decreased muscle mass (i.e. a low skeletal muscle mass index) are likelier to die (for any reason) at an earlier age than those with greater amounts of muscle.

"What's a skeletal muscle mass index?", you ask. Essentially, it's like the body mass index (BMI) but quantifies the relative muscularity of an individual according to their height, age, gender, etc. (The BMI doesn't account for muscularity or body composition.)

Hence, scientists are starting to use muscle mass indices instead of BMI as a predictor of longevity. After all, your body weight doesn't seem to be nearly as important as what your weight comprises (e.g. fat mass vs. muscle mass). It's a matter of quality, not just quantity.

In a pivotal study of 3,659 adults 55 years of age and older, total mortality was significantly lower in the fourth quartile of muscle mass index compared to the first [5]. This study found that the adjusted hazard ratio was 0.80 (95% confidence interval 0.66 – 0.97), meaning the individuals in the highest quartile of muscle mass were 20% less likely to experience any complication (including death) during the study, and we can be 95% confident that the "true value" lies between a 3-34% reduction of hazardous health events.

This evidence points to the intrinsic value of muscle mass as a biomarker for health and longevity, beyond its known benefits for physical strength and endurance.

Naturally, this begs the question, "Does resistance exercise increase lifespan in humans?" Evidentially, yes; that seems to be the case, even if there's no causal link between muscle mass and longevity.

Much like the aforementioned research, several studies have found a similar inverse association between muscle function (e.g. muscle strength and power) and the risk of all-cause mortality [6, 7, 8]. This lends further credence to the view that continual resistance exercise can enhance longevity; it's not just about getting as buff as possible in your early-to-middle adult years to live longer.

Of course, this topic has plenty of nuance, and exercise of any type is generally good for keeping us youthful. While resistance exercise and a proper high-protein diet is the best way to improve body composition and help offset the age-related loss of muscle mass we experience as we grow older, cardiovascular exercise is also a useful tool for prolonging the lifespan [9].

The Role of Skeletal Muscle Mass in Disease and Premature Death Prevention

Obviously, the primary role of skeletal muscles is to move the bones of our body. But skeletal muscle is a complex organ with diverse anatomical and physiological roles influencing our overall health. For example, muscle tissue plays a direct role in metabolic health, with skeletal muscle acting as the primary site for glucose uptake, thus influencing blood sugar levels and insulin sensitivity; increased muscle mass has been linked to better insulin sensitivity, thereby reducing the risk of type 2 diabetes and other chronic diseases [10].

Similarly, a strong musculature supports cardiovascular health by maintaining healthy blood pressure levels, aiding lipid metabolism, and fighting chronic inflammation [11]. The metabolic demand of muscle tissue also contributes to a higher basal metabolic rate, making it easier to manage weight and prevent visceral fat accumulation.

Sarcopenia: The Fight Against Father Time

When we lose muscle mass due to progressive aging, we are experiencing sarcopenia. The etiology of sarcopenia is multifactorial, involving a sedentary lifestyle, inadequate nutrition, chronic inflammation, and diminutions in anabolic hormone production, all of which can lower muscle mass in a hurry.

The consequences of having relatively low muscle mass are far-reaching, including increased risk of falls, frailty, and higher morbidity and mortality rates. We can infer the longevity of benefits of being relatively muscular by examining the evidence on sarcopenia, a key factor of poor health outcomes in the elderly [12].

To be clear, sarcopenia is a natural ramification of aging, and every adult experiences it to a degree as they grow older. However, when this age-related deterioration of muscle mass is left unmitigated it can increase the risk of chronic disease, such as cardiovascular disease and diabetes/insulin resistance [13].

Sarcopenia has traditionally been considered an inescapable phenomenon of aging, but there are plenty of older adults who have defied that notion. (Look at Transparent Labs Athlete Paul Sklar, for example.)

While it is completely "normal" to lose some muscle mass as you age, you can build and maintain muscle well into the latter part of your life. (Hint: weight training plays a big role, and so does protein ingestion.)

Higher Muscle Mass Index = Longer Lifespan, to a Point...

Increasing muscle mass and strength is almost always a good (read: healthy) goal to strive for, but there certainly does come a point where you can be overly muscular. Numerous case studies of athletes and bodybuilders taking anabolic androgenic steroids (AAS) and other performance-enhancing drugs make it clear that there are lasting consequences of carrying excess muscle mass, especially for cardiac function [14].

Being morbidly obese is not great for longevity; ironically, having a superhuman physique is arguably just as bad. It's virtually impossible to retain all the muscle from AAS use throughout the lifespan (assuming there aren't health complications before that point).

The key point here is that building muscle and maintaining it as an older adult is undoubtedly beneficial for our health. However, like most anything considered "healthy," too much can turn it in the other direction.

Exercise and Diet: Pillars of Longevity

Exercise, particularly resistance training/lifting weights, stands out as a cornerstone for increasing and maintaining muscle mass at any age. Regular resistance exercise stimulates muscle growth through hypertrophy and enhances neuromuscular junction efficiency, contributing to greater muscle strength and functional capacity. The benefits of such training extend beyond muscle health, encompassing improved metabolic rate, bone density, and psychological well-being.

Incorporating a variety of exercises targeting all major muscle groups, ensuring progressive overload, and allowing adequate recovery time are key principles for effective muscle strengthening. Additionally, endurance exercises, such as walking, swimming, or cycling, support cardiovascular health and can complement strength training by promoting overall fitness.

Dietary protein is essential for muscle repair and growth, serving as the building block for muscle tissue. The relationship between protein intake and muscle health is well-documented, with evidence suggesting that higher protein diets support muscle hypertrophy and recovery from exercise. For older adults, higher protein intake is particularly important to counteract the natural decline in muscle mass associated with aging.

Optimizing muscle protein synthesis is a matter of protein quality, timing, and quantity. Consuming a generous amount (e.g., 30 grams) of protein from high-quality, complete sources like whey protein, lean animal meats, dairy products, and eggs throughout the day, particularly after exercise, will maximize muscle protein synthesis. For vegetarians and vegans, plant-based protein powders made with rice and pea protein are also viable options for building and maintaining muscle tissue.

It's Never too Late to Build More Muscle Mass

While older adults and seniors should refrain from any workout that hurts their joints or exacerbates a preexisting health condition, it’s never too late to transform your body and improve your muscular strength. Resistance exercise, specifically weight training, is the best way to increase lean mass and maintain healthy muscle tissue (assuming your nutrition is on point).

Alas, you might not be able to build muscle mass as quickly or put up the same numbers on the bench press as you did when you were younger. An unfortunate consequence of getting older is the body starts to "slow down" a bit; metabolic rate drops, anabolic hormones like testosterone decline, muscle tissue breaks down, and joints become less resilient to mechanical stress.

But frankly, it’s not about where you start or who you "used to be" that matters; it's about who you are right now and where you finish. Get up and move your body, and lift some (relatively) heavy barbells from time to time to reach the latter years of life with health, strength, and vigor.