Why Muscle Is the Organ of Longevity
By Dr Michael Lynch
If I could prescribe one thing to almost every man over the age of 35, it wouldn't be a supplement.
It wouldn't be testosterone.
It wouldn't even be a medication.
It would be more muscle.
That might sound surprising, but over the past decade we've completely changed the way we think about skeletal muscle. It's no longer viewed simply as the tissue that helps you lift heavy objects or look good at the beach. Instead, research has shown that muscle functions as one of the body's most important metabolic and endocrine organs, influencing everything from blood sugar control and cardiovascular health to immune function and healthy ageing.
The amount of muscle you carry—and perhaps more importantly, your ability to maintain it as you age—may be one of the strongest predictors of how well you'll live in your later years.
Muscle: More Than Strength
Most people think of muscle as something that allows movement.
In reality, skeletal muscle performs hundreds of functions throughout the body.
It is the body's largest reservoir for glucose disposal, helping regulate blood sugar after meals. It stores amino acids that become essential during illness or injury. During exercise, muscle releases signalling molecules called myokines, which communicate with the brain, liver, fat tissue and immune system.
In many ways, muscle behaves like an endocrine organ.
This means that when you improve your muscle health, you're improving much more than your strength—you are improving the health of your entire body.
The Muscle–Longevity Connection
One of the most consistent findings in ageing research is that people with greater muscle mass and better muscle strength tend to experience:
Lower rates of cardiovascular disease
Better insulin sensitivity
Lower risk of type 2 diabetes
Reduced frailty
Lower rates of falls and fractures
Improved cognitive health
Greater independence later in life
Lower overall mortality
Interestingly, muscle strength often predicts health outcomes even better than muscle size alone.
Simple measures such as grip strength or the ability to repeatedly stand from a chair have been shown to correlate with future disability, hospitalisation and even lifespan.
The message is clear: maintaining muscle is not about vanity—it is about preserving function.
We Begin Losing Muscle Earlier Than Most People Realise
From around the age of 30, most adults begin to gradually lose muscle mass.
Without resistance training, this loss accelerates with each decade.
At the same time we often become:
Less physically active
More insulin resistant
More sedentary
More likely to accumulate abdominal fat
This combination creates a vicious cycle.
Less muscle leads to poorer metabolic health, which makes exercise harder, which further accelerates muscle loss.
Eventually this contributes to sarcopenia—the age-related decline in muscle mass and strength that is strongly associated with frailty and loss of independence.
The good news?
This process is remarkably modifiable.
Muscle Is Your Metabolic Engine
After eating carbohydrates, most glucose is cleared from the bloodstream by skeletal muscle.
Healthy muscle acts like a sponge, absorbing glucose and storing it as glycogen.
The more healthy muscle you have—and the more physically active that muscle is—the more efficiently your body handles carbohydrates.
This helps explain why resistance training is one of the most effective interventions for improving insulin sensitivity and reducing the risk of type 2 diabetes.
It also highlights why losing muscle can make weight management progressively more difficult as we age.
Muscle Produces Anti-Inflammatory Signals
When you exercise, your muscles don't simply contract.
They actively communicate with the rest of your body by releasing proteins known as myokines.
These signalling molecules influence:
inflammation
metabolism
blood vessel function
brain health
immune regulation
Many researchers now believe these beneficial signals help explain why regular exercise reduces the risk of so many chronic diseases.
The benefits of exercise are not confined to the muscles themselves—they ripple throughout the body.
Muscle Protects You During Illness
Think of muscle as your body's emergency reserve.
During major illness, surgery or trauma, the body draws upon stored amino acids within muscle to support immune function, wound healing and recovery.
People entering hospital with poor muscle reserves often experience:
longer admissions
slower recovery
higher complication rates
greater loss of independence
In contrast, individuals with better muscle mass generally tolerate physiological stress more effectively.
Muscle and Healthy Hormones
Hormones and muscle have a two-way relationship.
Healthy testosterone levels support muscle maintenance, while regular resistance training also improves hormonal health through multiple pathways.
It's important to remember that testosterone is only one part of the equation.
Without:
progressive resistance training
adequate protein
sufficient sleep
good nutrition
even optimal hormone levels won't build meaningful muscle.
Likewise, men with genuine testosterone deficiency often struggle to maintain muscle despite doing everything else well.
A thorough assessment should always consider the whole picture rather than focusing on a single blood test.
How Much Muscle Do You Need?
There isn't a magic number.
Instead, ask yourself:
Are you getting stronger each year?
Can you comfortably carry your groceries?
Can you climb stairs without difficulty?
Could you get up from the floor without using your hands?
Are you maintaining muscle as you age rather than gradually losing it?
These functional questions often matter more than chasing an arbitrary body weight.
Five Ways to Build Your Longevity Organ
1. Lift Weights
Aim for resistance training at least two to four times per week.
Prioritise compound movements such as squats, rows, presses and deadlifts where appropriate.
2. Eat Enough Protein
Most active adults benefit from spreading protein intake evenly across the day.
For many older adults, this often means consuming more protein than they currently do.
3. Prioritise Sleep
Muscle growth occurs during recovery.
Poor sleep impairs recovery, hormone regulation and training performance.
4. Stay Active Every Day
Formal exercise is important, but so is regular movement throughout the day.
Walking, climbing stairs and avoiding prolonged sitting all contribute to maintaining muscle function.
5. Address Medical Issues Early
Low testosterone, untreated sleep apnoea, chronic illness, nutritional deficiencies and certain medications can all impair muscle health.
These are often treatable—but only if recognised.
The Bottom Line
For decades, medicine focused almost exclusively on treating disease once it appeared.
Modern longevity medicine asks a different question:
How do we preserve function before disease develops?
Muscle sits at the centre of that conversation.
It helps regulate metabolism, supports healthy ageing, protects against illness, preserves independence and reduces the risk of many chronic diseases.
Building muscle isn't about becoming a bodybuilder.
It's about creating physiological reserve for the decades ahead.
Every kilogram of healthy muscle is an investment in your future health.
If you're over 35 and you're not actively trying to maintain or build muscle, you're likely moving in the wrong direction.
The earlier you start, the greater the dividends you'll reap—not just in strength, but in quality of life for years to come.
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