Most people treat muscle as cosmetic, or as something athletes worry about. Physiologically it's closer to an organ: your largest site for disposing of blood glucose, your reserve of amino acids during illness, and — through the strength and balance it provides — the single biggest determinant of whether you stay independent as you age. Unlike most organs, it responds to training at essentially any age.
Why muscle is metabolic tissue
- Glucose disposal. Contracting muscle can pull glucose out of the blood without insulin. Skeletal muscle is the body's biggest sink for a carbohydrate load, which is why resistance training improves glycaemic control independently of weight loss.
- Amino acid reserve. During illness, injury or inadequate intake, the body draws on muscle protein to supply what it needs. Starting with less reserve means less buffer when you're sick.
- Signalling. Contracting muscle releases factors that act on other tissues. The biology here is active research, but "muscle talks to the rest of the body" is well supported.
- Mechanical function. Strength, power, balance, bone loading, and the ability to get off the floor.
Sarcopenia: the decline nobody notices
Muscle mass and strength generally peak in early adulthood and decline thereafter — the rate varies enormously between people and is heavily driven by activity rather than by age alone. The trajectory is not fixed:
- Disuse is the dominant accelerator. Bed rest and immobilisation cost muscle quickly. So does a sedentary decade.
- Loss is not uniform. Fast-twitch fibres — the ones used for power and for catching yourself when you trip — are preferentially affected with age.
- Strength declines faster than mass, so someone can look unchanged and be meaningfully weaker.
- When combined with low physical activity, this reaches the clinical threshold of sarcopenia, which is associated with falls, fractures, loss of independence and higher surgical risk.
The two levers that actually work
1. Resistance training
The signal that drives muscle protein synthesis is mechanical load — muscle contracting against meaningful resistance. Details that matter:
- Dose: two to three sessions a week is consistently enough; more isn't linearly better and costs recovery.
- Intensity: working near your current capacity for the last repetitions matters more than the absolute weight. "Feeling hard by the end of the set" is a reasonable field guide.
- Range and progression: full range of motion, and gradually increasing load, reps or difficulty over time. Progressive overload is the whole mechanism.
- Legs and hips matter most for independence — squats, step-ups, hip hinges, lunges carry over to real function.
- Power and balance — getting up quickly, single-leg work — protect against falls in a way steady-state cardio doesn't.
- It works in older adults. Strength gains from resistance training are well documented in people in their seventies, eighties and beyond. The ceiling is lower and the rate slower, but the response is real.
2. Protein intake
Training provides the signal; protein provides the material.
- Total daily intake matters more than timing — though spreading protein across meals is a reasonable and low-cost habit.
- Older adults likely need more per kilogram than younger adults, because the anabolic response to a given dose is blunted with age. Requirements vary by individual and clinical context.
- Distribution: many people eat little at breakfast and most at dinner, which is backwards for stimulating synthesis repeatedly.
- Most people in high-income countries already eat adequate total protein; the gap, where it exists, is usually in older adults, people with reduced appetite, and those eating restricted diets.
Things that quietly cost you muscle
- Prolonged sedentary periods — independent of whether you also exercise
- Unplanned or aggressive weight loss, which often takes lean tissue with it
- Inadequate protein during illness or recovery
- Chronic sleep restriction and poorly managed stress, both of which impair recovery
- Excess alcohol
- Some medications and untreated low testosterone or thyroid disease — worth discussing rather than assuming
Where to start, realistically
- Two sessions a week, 30 minutes. That's the entire minimum effective dose for most people.
- Cover the basics: a pushing movement, a pulling movement, a squat or step-up, a hip hinge.
- Bodyweight and bands count. Resistance is resistance — you don't need a gym to start, though heavy loads help later.
- Add protein to breakfast if yours is currently mostly carbohydrate.
- Keep one power element — stair climbing, or getting up from a chair without using your hands.
- If you have cardiovascular disease, uncontrolled blood pressure, or a musculoskeletal injury, check with your clinician first about appropriate loading.
Bottom line
Muscle isn't vanity — it's your glucose sink, your protein reserve, and the thing most likely to keep you living independently at 85. It declines mostly through disuse rather than through age itself, and it responds to two sessions a week of real resistance plus adequate protein at any point on the curve. Very few preventive interventions have that combination of effect size and availability.
This article is educational and not a substitute for medical advice. Check with your clinician before starting a new training programme, particularly if you have existing medical conditions.