Muscles, the 'longevity organ': why they weaken after 30 and how they can be supported

Muscles are sometimes called the "longevity organ" due to their role in regulating metabolism and maintaining independence in old age. Muscle mass and strength decline with age, but exercise and proper nutrition can slow this process.

The role of muscles in the body

Joey Muñoz, a doctor of nutritional sciences, explained in an article published by Cronometer why musculature matters regardless of whether a person engages in competitive sport: "It's easy to think of muscles as something only athletes or bodybuilders need, but the science has made it clear: maintaining muscle mass is one of the most powerful indicators of health and longevity. Muscle tissue is active, continuously influencing metabolism, hormones, and immune function. Unlike fat, which stores energy, muscles use it, making them one of the primary drivers of metabolic rate. The more muscle mass you have, the more efficiently your body manages the energy you consume."

Muscles also play an important role in regulating blood sugar, contributing to glucose utilisation and its storage as glycogen. According to the specialist: "Muscles aren't just about movement; they're also one of the body's most powerful regulators of blood sugar. When you consume carbohydrates, muscles act like a sponge, drawing glucose from the blood and storing it as glycogen for energy. This process improves insulin sensitivity, helping the body maintain stable blood sugar levels. When muscle mass declines, this regulatory system weakens. The body becomes less efficient at managing glucose, which can lead to insulin resistance and increase the risk of metabolic diseases such as type 2 diabetes."

Muñoz emphasises that the number on the scales alone does not reflect one's health, and that body composition also matters: two people of the same weight can have very different proportions of muscle and fat, and therefore different metabolic profiles. Equally, muscular strength matters for everyday activities such as rising from a chair, climbing stairs, or moving about independently.

Why we lose muscle mass and how the decline can be slowed

According to the US National Institute on Ageing, muscle mass and strength peak at around 30 to 35 years of age, after which they gradually decline, with the decline accelerating in later life. Physical inactivity and inadequate nutrition promote sarcopenia, a condition characterised by the progressive loss of muscle mass, strength, and function.

Joey Muñoz explains: "Every decade after the age of 30, you can lose between 3 and 8% of your muscle mass if you do nothing to preserve it. This gradual decline doesn't just change how you look — it affects how you move, how you recover, and even how your body responds to illness. Sarcopenia has been associated with a greater risk of falls, slower recovery from surgery, and increased vulnerability to infection. In other words, it's not just about living longer, but about staying strong for longer."

Strength exercises — with weights, resistance bands, or your own body weight, adapted to individual ability — can help maintain mobility. The specialist adds: "Think of your muscles as the foundation of your body. Without them, everything becomes harder: climbing stairs, carrying shopping, getting out of bed, or simply keeping your balance. With them, life feels easier. You move better, you recover faster, and your body stays functional for longer. That's what ageing well truly means: not avoiding the passage of time, but making those years count."

The US National Institute on Ageing notes that an active lifestyle can slow the decline in muscle strength, and that many older adults can improve their musculature through physical exercise.