Why muscle strength is a sign of good health

My new book, Deep Fitness: The Mindful, Science-Based Strength-Training Method to Transform Your Well-Being in 30 Minutes a Week, coauthored with Philip Shepherd, is coming out on October 12, 2021. The following is an adapted excerpt from the book. If you want to learn more, pre-order now!

Traditionally, there are four indicators a doctor looks at to assess a patient’s well-being: blood pressure, heart rate, breathing rate, and temperature. But in 2018, a team of researchers suggested that muscle mass should be included as one of the vital signs of health.

After studying a variety of patients, the researchers consistently found that greater muscle mass led to better outcomes across a wide range of conditions. Patients with more muscle had better overall survival rates, better responses to cancer therapies, and better outcomes where chronic obstructive pulmonary disease was a factor; they also showed decreases in Alzheimer’s, length of stay in the ICU ward, and complications due to surgery.

Two other studies—with over 2 million people in total—found that low muscle strength was associated with a significantly elevated risk of death by any means (car accident, illness, anything). And that finding was independent of other factors, such as being sedentary, physical activity, or muscle mass itself.

A lack of muscle goes hand in hand with physical inactivity, and the list of chronic diseases that inactivity may contribute to is staggering. It includes, among many others, cardiovascular disease, various cancers, obesity, diabetes, high blood pressure, cognitive disfunction, lung disease, osteoporosis, and stroke. By the same token, the remedy is clear: a 2018 paper in the Annual Review of Physiology plainly declares that “exercise should be prescribed as medicine for many chronic diseases.”

Research has demonstrated that sarcopenia, the loss of muscle mass and strength as we age, plays a role in the six most deadly diseases in the USA—heart disease, cancer, chronic lower respiratory diseases, stroke, Alzheimer’s, and diabetes. It is also associated, independent of age, with “the worst rates of morbidity and mortality in various diseases, which reflects the extent to which sarcopenia can impact the treatment outcome.”

No wonder there is a growing perception among health professionals that sarcopenia is the common variable that leaves us vulnerable to chronic disease.

Dr. Gabrielle Lyon, who pioneered “muscle-centric medicine,” has declared that “the obesity epidemic is not really an obesity epidemic—it’s an epidemic of low muscle mass.” Doug McGuff—an American medical doctor, author, and expert on the physiology of strength training—has declared: “Aging and diseases of modern civilization are 100% related to pathological muscle loss that occurs with aging: a.k.a. sarcopenia.”

This is more than a recognition that muscle strength should be included as a vital sign. It is a recognition that muscle strength is the bedrock on which our metabolic health rests.