If you’re over 40 and your exercise routine is mostly walking, running, or spin classes, you’re doing something genuinely good for your heart. But if that’s the whole plan, there’s a gap in it that most people don’t find out about until it’s already causing problems.
The myth
For decades, the default advice for staying healthy as you age has been “move more” usually meaning cardio. It’s not wrong, exactly. It’s incomplete. Cardiovascular exercise is excellent for heart health, lung capacity, and mental wellbeing. But it was never designed to preserve muscle or bone, and after 40, that’s precisely what starts to matter most.
What actually happens after 40
Muscle loss, which begins gradually in your 30s, accelerates from your 40s onward, and bone density starts declining around the same time, particularly for women approaching and going through menopause. Neither of these processes is meaningfully slowed by cardio alone, because cardio doesn’t apply enough mechanical load to muscle and bone to trigger the body’s “keep this, I need it” response.
Resistance training does. Lifting weights, or working against resistance in any form, signals your body to maintain and build muscle, and stimulates the bone remodelling process that keeps bones dense and fracture-resistant.
Why this gets missed
Someone can run three times a week, feel genuinely fit, and still be quietly losing muscle and bone density in the background. Fitness trackers show heart rate and calories, not muscle mass or bone density, so this decline is invisible until it shows up as something concrete, a fall, a fracture, or simply feeling weaker than expected doing normal tasks.
What the research shows
Studies consistently show that resistance training is one of the few interventions that directly slows both sarcopenia (age-related muscle loss) and osteopenia/osteoporosis (bone density loss). It also improves insulin sensitivity, balance, and joint stability, all factors that become increasingly important for staying independent later in life. Cardio contributes to overall health, but the muscle- and bone-preserving effects are specific to resistance training.
Common mistake
The common mistake isn’t doing cardio; it’s treating it as sufficient on its own. The two aren’t competitors; they do different jobs. Cardio protects your heart. Resistance training protects your muscle, bone, and functional strength. After 40, you genuinely need both to age well.
How to solve it
You don’t need to choose between them or overhaul your routine:
- Keep your cardio if you enjoy it; it’s still good for you
- Add 2–3 resistance training sessions per week
- Prioritise compound movements: squat, hinge, push, pull and carries. They load multiple muscle groups and joints at once
- Progressively increase the challenge over time, rather than staying at the same light weight indefinitely
Cardio keeps your heart young. Strength training keeps your muscles, bones, and independence young. After 40, doing only one of them is like maintaining half a house and the other half quietly falls into disrepair. Adding resistance training isn’t about replacing cardio; it’s about closing a gap most people don’t know exists until it costs them something.
If you’re not sure how to balance the two, come in for a No Sweat Intro. We’ll look at where you are now and build a plan that protects your heart and your strength.