The truth about anabolic resistance with ageing

Talk about rubbing salt into the wound.

Sure, ageing comes with a loss of muscle and strength, which has a big impact on your ability to:

Stay independent
Avoid chronic disease
And ultimately, maintain a good quality-of-life

But it may also limit your capacity to respond to “anabolic” stimuli—like resistance exercise or protein intake.

The very things that offset muscle loss in the first place.

It’s kinda cruel, really…

But is this so-called “anabolic resistance” just part of ageing, or are other factors at play?

New data challenges the belief that aging diminishes your ability to respond to the key stimuli needed for muscle and strength growth.

And it shows how you can keep your muscles sensitive to these triggers—for longer.

Let’s dive in.

The thing with anabolic resistance and ageing

So ageing may blunt your response to resistance exercise or protein intake.

And this ultimately means your gains in muscle mass and strength may be less than a younger person following the same exercise or nutrition regime.

But why might this be?

Part of it may stem from a reduced ability of older muscle to activate muscle protein synthesis—the process of building new muscle tissue.

As an example, one study found younger adults had a 44% increase in muscle protein synthesis rates in the 24 hours after a resistance exercise session, while older adults showed only a 17% increase under the same conditions.

In other words, older muscle may become “resistant” to anabolic stimuli.

But here’s the thing:

Some studies do not support the existence of anabolic resistance in aged populations.

This may be explained by factors independent to (but linked with) ageing, such as:

Obesity
Chronic disease
Physical inactivity

All of which may drive anabolic resistance separate from ageing per se.

So the question is:

If older adults stay active and healthy, how does their response to exercise and nutrition stack up against their younger counterparts?

Is anabolic resistance “just ageing”, or are other factors at play?

Enter a 2024 study in the Journal of Cachexia, Sarcopenia and Muscle.

They had 20 younger and older men (aged 22 and 70 on average, respectively) do a single bout of resistance exercise followed by protein intake.

Now both the younger and older men were:

Lean (at least based on a BMI of under 25)
Healthy (free of cardiovascular of metabolic disease)
And physically active (2-3 times per week, but did not do any regular structured resistance exercise)

When they arrived at the laboratory, they were infused with a tracer to measure rates of muscle protein synthesis, and a resting muscle sample was taken from their outer thigh.

They then did a pretty hefty resistance exercise session on one leg (10 sets of 10 leg extensions with their individual 10-rep max load), and consumed a protein (essential amino acid) drink immediately afterwards.

This meant:

One leg did resistance exercise with added protein intake
While the other was exposed to protein intake alone

To capture changes in the rate of muscle protein synthesis and activity of the cellular machinery responsible, extra muscle samples were taken 1 and 3 hours after exercise.

This allowed insight into whether age influenced the anabolic response to resistance exercise and protein intake, or protein intake alone.

The anabolic potential of aged (but healthy) muscle

First of all, the anabolic stimuli worked.

Across both groups, exercise and protein intake boosted muscle protein synthesis rates by about:

95% after 1 hour
And 120% after 3 hours

And guess what:

There was no difference in this response between younger and older muscles.

If anything, the older adults had an even greater response, although there was no statistical difference between age groups.

These changes were matched by a similar activation of the cellular machinery driving muscle protein synthesis—pathways thought to become dysregulated with ageing.

In theory, this means both groups might expect similar muscle growth if they continued the program long-term.

While that wasn’t tested in this study, others have shown healthy 85+ year olds had similar gains in muscle size, strength, and functional performance after a period of resistance training to those up to 20 years younger.

The take home?

Anabolic potential is preserved in healthy, lean, and active older muscle.

There’s more to anabolic potential than age

The findings of this study ram home a key point:

Muscle and strength loss is not just ageing.

It’s compounded by other factors that often come with age—like inactivity, chronic disease, and increased body fat.

This reinforces the idea getting older doesn’t have to mean losing your muscle or physical ability.

Nor does it mean you can’t reap the benefits of staying physically active.

By staying active, healthy, and lean, you can keep your muscles sensitive to the potent effects of exercise and nutrition.

And more importantly, retain your ability to live better—for longer.

As always, thanks for being here!

Until next week,

Jackson

If you've got a moment, I'd love to hear your thoughts on this edition of The Weekly Exerciser.

Send me a quick message or email - I'll reply to every one!

PS: Did someone forward you this email? You can sign up to The Weekly Exerciser here.

IMPORTANT:

The information contained herein is of general nature only and does not constitute personal advice. You should not act on any information without considering your personal needs, circumstances, and objectives. Any exercise program may result in injury. We recommend you obtain advice specific to your circumstances from an appropriate health professional before starting any exercise program.