Why Maintaining Muscle as We Age Requires More Than Protein *Educational Purposes Only*

By Dr. John A. Robinson, NMD & Dr. Cristina Romero-Bosch, NMD
The Longevity Protocol™

One of the most visible signs of aging is the gradual loss of muscle. We get smaller, weaker, less powerful, and eventually less capable of doing the things that make life enjoyable.

But muscle loss is not simply a cosmetic consequence of getting older. Muscle is one of our most important longevity organs.

Maintaining muscle influences metabolic health, insulin sensitivity, bone health, balance, mobility, resilience after illness, and ultimately our ability to remain independent. At The Longevity Protocol™, preserving skeletal muscle is therefore one of our highest priorities.

An important 2026 study published in The Journal of Physiology, titled “Multifactorial Nature of Anabolic Resistance in Ageing Skeletal Muscle: A Systems Modelling Study,” helps explain why maintaining muscle becomes progressively more difficult with age.

The central concept is anabolic resistance.

Your Muscle Stops Listening as Well

Normally, eating protein—particularly amino acids such as leucine—signals skeletal muscle to increase muscle protein synthesis. Insulin and amino-acid signaling interact with pathways including mTORC1 to essentially tell the muscle:

We have nutrients available. Build and repair.

As we age, that signal becomes weaker.

Older muscle does not respond to the same anabolic stimulus as effectively as younger muscle. Muscle protein synthesis rises less after eating, while suppression of muscle protein breakdown can also become impaired. Over time, this imbalance contributes to sarcopenia: the progressive loss of muscle mass, strength, and function.

What makes this study particularly interesting is that the researchers asked a deeper question: Why does anabolic resistance occur?

Their answer fits remarkably well with how we approach longevity medicine.

There isn't one cause.

Aging Muscle Is a Systems Problem

The researchers examined several changes associated with aging, including reduced amino-acid availability and transport into muscle, impaired insulin-mediated anabolic signaling, lower mTOR and p70S6K levels, reduced mTORC1 sensitivity to leucine, and persistent muscle protein breakdown.

This is where our comprehensive approach to sarcopenia becomes particularly relevant. Testosterone, nandrolone and human growth hormone can influence overlapping aspects of the anabolic environment identified in this paper—supporting muscle protein synthesis, anabolic signaling, tissue recovery and the balance between muscle synthesis and breakdown. They do not all work through identical mechanisms, and this study did not specifically test these hormones, but their effects on the anabolic environment are one reason we consider them important tools in appropriately selected patients.

The important finding was that no single abnormality adequately reproduced the anabolic resistance seen with aging. Instead, anabolic resistance emerged when multiple impairments occurred together. Likewise, targeting only one problem generally could not completely restore the muscle-building response when the entire system was impaired.

This is an important lesson about aging itself. Aging is rarely the failure of one pathway. It is the progressive loss of coordination among multiple biological systems.

Why “Just Eat More Protein” Isn't Enough

Protein remains enormously important. Leucine is particularly significant because of its ability to stimulate mTORC1, and resistance training remains one of our most powerful anabolic signals.

But simply increasing one input may not fully overcome an aging biological system.

The authors specifically discuss nutritional interventions including amino acids, creatine and antioxidants, along with resistance and aerobic exercise and other therapeutic approaches. Their larger point is that successful treatment may need to address multiple interacting mechanisms simultaneously.

That is exactly how we approach muscle preservation at The Longevity Protocol™. We use essential amino acids and creatine, along with highly bioavailable protein sources such as hydrolyzed beef protein powder, to help provide the raw materials needed for muscle protein synthesis. We combine this with adequate dietary protein, progressive resistance training, metabolic optimization, inflammation control, quality sleep and appropriate recovery.

And then we look at the hormonal environment.

In appropriately selected patients, our strategy may include testosterone, nandrolone and human growth hormone to further support the anabolic environment, muscle preservation, recovery and body composition. These therapies do not replace nutrition or resistance training. They are additional tools that can be integrated into a much larger strategy.

In other words, we want to address both sides of the equation: provide the building materials and optimize the biological signals that tell the body what to do with them.

Muscle Is Your Longevity Reserve

We often tell patients that the muscle you build and preserve in your 40s, 50s and 60s becomes part of your physiological reserve later in life.

You are not training simply to look better today. You are building the strength that may allow you to travel at 75, carry your luggage at 80, get up from the floor at 85, play with your grandchildren, recover from surgery, survive an illness, and continue participating fully in your own life.

This study reinforces an idea central to The Longevity Protocol™: there will probably never be one intervention that solves aging.

When the researchers simulated multiple age-related impairments simultaneously—the scenario they suggest more closely represents older adults—restoring the anabolic response required a multifactorial therapeutic strategy.

That is longevity medicine in a nutshell.

Protein matters. Amino acids matter. Creatine matters. Exercise matters. Hormones matter. Metabolic health matters. Recovery matters. And they matter together.

Because the objective isn't simply to live longer. It is to preserve enough strength, vitality and physical capacity to continue living The Art and Science of Living the Well-Lived Life™.

Source:
McColl TJ, Moore DR, Emberly E, Church DD, Clarke DC. Multifactorial nature of anabolic resistance in ageing skeletal muscle: A systems modelling study. The Journal of Physiology. 2026;604(15):6405–6439.