Cardiovascular exercise gets the public health attention, and it deserves much of it. But for metabolic health, bone density and healthy ageing, resistance training does things that cardio cannot, and most adults do none of it.
Canadian activity guidelines recommend muscle-strengthening activity at least twice weekly alongside aerobic exercise. Adherence to that second half is poor — a large majority of adults meet neither, and the strength component is the one most often skipped entirely.
What muscle does metabolically
Skeletal muscle is the largest site of glucose disposal in the body. After a meal, muscle takes up a substantial share of circulating glucose, and it does so partly through pathways that do not depend on insulin. More muscle, and more active muscle, means more capacity to clear glucose.
This is why resistance training improves insulin sensitivity — including in people who do not lose weight doing it. The benefit is not mediated by the scale.
- Improved insulin sensitivity, measurable within weeks
- Better glycaemic control, with meaningful effects on A1C in type 2 diabetes
- Preserved resting metabolic rate, because muscle is metabolically active tissue
- Increased bone density — loading bone is the main stimulus for maintaining it
- Better lipids and blood pressure, though generally less than aerobic training delivers
The muscle-loss problem
Adults lose muscle mass steadily from around the fourth decade, and the loss accelerates later. It is gradual enough to be invisible until it produces something visible — difficulty on stairs, a fall, a slow recovery from an illness.
Weight loss compounds it. A significant proportion of weight lost through calorie restriction alone is lean tissue, and that proportion rises when loss is rapid. This is a live issue for people on GLP-1 medications, where loss can be fast and appetite suppression makes adequate protein intake harder.
What counts
Less than people assume. You do not need a gym, a barbell or a programme with a name.
- Bodyweight — squats to a chair, push-ups against a counter, step-ups, lunges, planks
- Resistance bands — inexpensive, portable, and genuinely effective
- Household weight — water bottles, a loaded backpack, grocery bags
- Machines or free weights if you have access and prefer them
The principles that matter across all of them: work the major muscle groups, take each set close enough to fatigue that the last repetitions are difficult, and gradually increase the challenge over time. Two sessions a week covering legs, back, chest, shoulders and core is a complete programme for most people. Twenty to thirty minutes is enough.
Starting safely
The main risk is doing too much too soon. Begin lighter than feels necessary, prioritise form over load, allow a day between sessions for the same muscle groups, and expect some soreness in the first fortnight that settles as you adapt.
Speak to a clinician first if you have uncontrolled hypertension, known heart disease, recent surgery, an unstable joint problem, active retinopathy, or osteoporosis with a fracture history. In almost all of these the answer is a modified programme rather than no programme — the risk of remaining sedentary is generally the larger one.
The long view
The strongest argument for resistance training is not metabolic at all. Muscle mass and grip strength are among the better predictors of independence in later life. Training now is the closest thing available to buying the ability to carry your own shopping at eighty-five, and the deposits have to be made decades earlier.
