As we get older, maintaining muscle is not just about eating enough protein or staying active. It is also about how well the body responds to those inputs.

Two important biological changes sit at the centre of age-related muscle decline: reduced anabolic signalling and lower cellular energy availability.

1. Reduced anabolic signalling: the “build muscle” signal gets quieter

When you eat protein or do resistance exercise, your body sends signals to repair and build muscle. This process is called anabolic signalling.

One of the key pathways involved is called mTOR, which acts a bit like a master switch for muscle protein synthesis. When the body senses enough amino acids, especially leucine, and receives the right exercise stimulus, mTOR helps tell the body: we have what we need — let’s build and repair muscle.

What changes with age?

• The body becomes less sensitive to protein intake.
• The muscle-building response after meals can be reduced.
• The same workout or meal may no longer create the same strong response it once did.

This is often called anabolic resistance. It does not mean the body cannot build muscle — it simply means the signal may need to be stronger, more consistent, and better supported.

2. Reduced energy availability: less fuel to do the work

Building and maintaining muscle takes energy. Every time your body repairs tissue, creates new muscle proteins, or recovers after exercise, it uses ATP — the body’s core energy molecule.

As we age, the mitochondria — often called the energy factories of the cell — can become less efficient. That means the body may have a harder time producing and managing the energy needed for muscle repair, recovery, and performance.

Think of it like renovating a house. Anabolic signalling is the instruction to start building. Energy availability is the electricity, tools, and workers needed to actually complete the job.

Where protein fits in

Protein provides the building blocks your body needs to repair and maintain muscle. These building blocks are called amino acids.

But protein does more than provide raw material. Certain amino acids, especially leucine, also help trigger the muscle-building signal. This is why protein quality matters, not just protein quantity.

With age, the body often needs a stronger protein signal to get the same response. That can mean prioritising high-quality protein, spreading protein across the day, and pairing it with resistance exercise.

Where creatine fits in

Creatine is naturally produced in the body and stored mainly in muscle, where it helps support the rapid recycling of ATP. In other words, creatine helps your cells quickly top up their energy supply when demand increases.

This is why creatine is often discussed in relation to strength, power, exercise performance, and healthy ageing. It does not replace protein, and it does not replace resistance exercise. Instead, it supports the energy system that helps muscles perform, recover, and adapt.

For older adults, this matters because muscle maintenance is a two-part challenge: the body needs the right signal to build and the right energy support to follow through.

The simple takeaway

Age-related muscle decline is not just about “getting older”. It is partly about the body becoming less responsive to muscle-building signals and less efficient at producing the energy needed for repair and recovery.

• Protein provides amino acids and helps trigger muscle-building signals.
• Resistance exercise gives the body a reason to maintain strength and muscle.
• Creatine supports the cellular energy system that helps muscles perform and adapt.

Together, these strategies can help support strength, energy, confidence, and healthy ageing.