Blog · Strength training over 40

Moving is not the same as building

By Remko Opdam · 5 June 2026 · 4 min read

In short

Moving, whether that is group classes or cardio, and building muscle are two different things. The second one needs mechanical tension, a plan and progression.
After 40 you lose muscle mass gradually without strength training, even if you move plenty.
Two targeted strength sessions a week alongside your existing classes is already enough to build.

I had a coaching session recently with a woman in her early sixties. She had changed the way she ate and had genuinely lost some weight. Doing well, then. But she said something that stayed with me:

"I have lost weight, but I cannot see it."

And her own suspicion was right: she was worried she had lost more than fat, that muscle had gone too.

I asked what she was doing for exercise. The answer: group classes. Bodyshape, circuit training, bodypump. Several times a week. So she was moving plenty. And still she had begun to doubt whether it was bringing her closer to her goal.

Two different things

This is one of the biggest misunderstandings I come across: moving and building are treated as the same thing. They are not.

Group classes are valuable. You burn calories, you train your fitness, you move your body, and it is sociable. Nothing wrong with any of that, and if you enjoy it, keep going.

But building muscle asks for something else. For that you need three things:

Mechanical tension. Your muscles have to be loaded more heavily than they are used to. Not more often, but heavier.
A plan. The same exercises, built up deliberately, so you can measure your progress.
Progression. A little more weight or a few more repetitions every week or two. That is the signal your body builds on.

A group class is designed for the whole group. The same weight, the same tempo, roughly the same load every week. Fine for maintenance, but your body gets no reason to become stronger.

And after 40 this really starts to bite. From then on you lose muscle mass every year unless you put something against it. Losing weight without strength training speeds that up: part of what disappears is not fat but muscle. Hence "I have lost weight but I cannot see it".

"But strength training is boring"

She said as much, and I understand it. A room full of machines is less sociable than a class with music.

But here is how I see it: doing the same thing every week and seeing no change is also boring. Strength training gets interesting the moment you start tracking progress. Last week eight repetitions at 30 kilos, this week nine. That is a game with yourself, and you win it a little every week.

The training plan misunderstanding

At the end of the conversation she hoped I would tell her which exercises to do. I get that question almost every time, and it makes sense.

But I have written out enough training plans in the past to know what happens to them: almost nobody gets a result. Not because the plans were bad, but because a plan does not solve the problem.

Results do not come from a plan. They come from how well you perform the exercises, whether you dare to push yourself a little, whether you stay injury free, and whether you keep turning up.

You can find a list of exercises in five minutes. Technique, build-up and consistency are where the real work sits. That is exactly where coaching makes the difference, and why I no longer write standalone plans.

What you can do with this yourself

Three things you can do this week without buying anything:

Keep your group classes, but add two fixed strength sessions. It does not have to replace anything. Twice a week of targeted strength alongside your classes is enough to build.
Pick five or six basic exercises and get a little better at them every week. Write down your weights and repetitions. What you do not track does not grow.
Do not measure progress with the scales alone. The scales cannot tell fat from muscle. Look at what you lift, how your clothes fit, and how the stairs feel.

And if you have lost weight but cannot see it, the odds are your body is not asking for less. It is asking for heavier.

Frequently asked questions

Is moving not enough to keep my muscle mass?

No. Movement on its own is usually not enough to keep or build muscle mass, certainly not after 40. Group classes such as bodypump or circuit training burn calories and train your fitness, but they rarely give your muscles the mechanical tension and progressive load needed to get stronger. Without targeted strength training you lose muscle mass gradually from 40 onwards, and if you lose weight without strength training, part of what disappears is muscle rather than fat. That explains why people sometimes lose weight and do not see it in the mirror. The answer is not necessarily to move more, but to add two targeted strength sessions a week alongside your existing classes, with exercises you make slightly heavier week after week. That way you keep the classes for enjoyment and fitness while building muscle deliberately, instead of choosing one or the other.
Source: strength training and sarcopenia (PMC) →

How many times a week do I need to lift to build muscle?

For most people two or three strength sessions a week are enough to build muscle, provided you repeat the same exercises in a structured way and raise the load gradually. Once a week can help you keep muscle, but it gives less consistent progress. More important than frequency is progression: a little more weight or a few more repetitions every week or two, so your body has a reason to get stronger. Randomly changing exercises, or a plan you never build on, delivers little even if you train often. At Infinite Health we build this up step by step, matched to your current level and the time you have, so the load always offers just enough challenge without raising the injury risk. Even at twice a week that is more than enough to see a measurable difference in strength and body composition within a few months.
Source: RIVM Dutch activity guideline, at least twice a week →

Can I do strength training at home, or do I need machines?

Training at home works fine, certainly at the start. With your own body weight, a set of resistance bands and a couple of dumbbells you can get a long way, and for someone just starting that is often exactly enough to make progress in the first months. The bottleneck comes later: strength training works through progressive overload, so the resistance has to keep growing with what you can handle. At home you hit a ceiling sooner, because at some point you cannot add weight. Body weight squats become fitness work rather than strength work. The second issue is technique: with heavier exercises it is hard to see for yourself whether the movement is right. Starting at home is fine, and staying at home works as long as you can keep building. If you notice you have been stuck on the same resistance for months, that is the signal you need more weight than home can offer.