How Muscles Change with Aging

by Fit After Fifty
Closeup of a person flexing their bicep

Sarcopenia is age-related muscle loss, and it starts as early as the 40s but accelerates after the age of 75. Many factors contribute to sarcopenia, including age, nutrition, hormones, medical conditions, and activity level. The process has three stages, and they progress from loss of muscle mass to loss of strength and physical performance.

An Unnerving Part of Aging

Our muscles function under the direction of the neurons in our brains, much like electrical switches. Large muscles, such as the quadriceps, have many individual muscle fibers, and therefore, many neurons controlling them. Small muscles that require precise movements have fewer neurons controlling them. Neurons are not able to replace themselves, and they have a set lifespan. As we age, the number of neurons begins to decline, and the muscle cells under their control atrophy and eventually die.

Unbalanced Protein Metabolism

A balance of synthesis and breakdown maintains the amount of protein in our bodies. Inefficient protein synthesis causes our muscle mass to decrease. Researchers do not fully understand exactly how protein synthesis becomes inefficient, but hormones and nutrition are two parts of the process.

Hormonal Drop-Off

As we age, the levels of hormones decrease, and we also develop resistance to them, such as in type 2 diabetes. Growth hormone (GH), insulin-like growth factor (IGF-1), and testosterone are three such hormones that are directly involved in protein metabolism. As these hormones decrease and we become resistant to them, our protein metabolism is affected, resulting in loss of muscle mass.

Inadequate Nutrition

Older adults have trouble getting adequate calories because of issues with taste, the mechanics of eating, and reduced appetite. With this reduction in calorie intake, the amount of protein consumed is inadequate for the body to make muscles, resulting in loss of mass.  

Reversing Age-Related Loss of Muscle Mass

The good news is that we can reverse age-related muscle loss. With resistance training and adequate nutrition, we can build muscle mass into our 90s! Multiple studies have shown this, and plenty of senior athletes attest to this fact. Getting enough protein is also essential, and nutritionists recommend eating 1.2 grams of protein per kilogram of body weight. So, get out there, start snacking on protein, lift those weights, and put the brakes on sarcopenia.

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