Is Cardio Enough After 40? What Strength Training Adds

In my twenties and thirties, I ran twenty to thirty miles a week. I was doing something difficult, regularly. By the measures I paid attention to, I was doing well.

I was also avoiding the weight room.

I thought all that running meant I had exercise covered. I wasn’t asking what I was leaving out.

If you walk, run, cycle, or swim, and wonder whether you need to lift as well, here is the short answer: aerobic exercise is valuable, but it does not automatically cover your need for muscle-strengthening activity. Public-health guidance includes both, rather than asking you to choose between them. ^[1] The question is how strength training fits alongside the activity you already enjoy.

The harder question is why someone who already makes time for exercise can overlook that distinction.

What my mileage did not tell me

I have written elsewhere about the embarrassment that kept me away from the weight room for twenty-two years. The useful part of that story here is what happened afterward: I could build an active life around the thing I was avoiding.

Running gave me a clear measure. Miles completed. Another week of exercise. Something I could point to as evidence that I was taking care of myself.

There was nothing wrong with those miles. The mistake was asking them to answer every question about my physical capacity.

How far can I run? How much resistance can I move with control? Can I produce more force than I could a few months ago? Those questions overlap, but they are not interchangeable.

You can be committed to exercise and still have a gap in what you train. Recognizing the gap does not make your existing work a waste. It tells you where to put some of your next effort.

What strength training adds

Strength training makes resistance something you deliberately practice and adjust. That resistance might come from a machine, a dumbbell, a band, or your own body. The important distinction is that improving your ability to work against it is part of the plan.

The American College of Sports Medicine's current review finds that resistance training improves strength and muscle size, along with several measures of physical performance, compared with doing no exercise. It also makes clear that useful training can take multiple forms. There is no requirement to begin with an elaborate routine or a particular piece of equipment. ^[2]

This does not mean that running never challenges your muscles, or that lifting replaces the benefits of aerobic activity. It means that being active is too broad a description to tell you whether strength is receiving deliberate attention.

Think about what your exercise routine actually asks you to improve. If every measure is distance, pace, time, or steps, what tells you whether you are getting stronger?

The physical activity guidelines include both aerobic exercise and muscle-strengthening activity. For adults, the strengthening recommendation is activity of moderate or greater intensity involving all major muscle groups on at least two days each week. That distinction matters: being consistent with cardio does not automatically mean strength is covered. ^[1]

Why frame this around forty?

Forty is not a biological deadline. It is a useful point to reconsider a routine you may have followed for years. Finding an activity you enjoy and sticking with it matters. It is still worth asking what that routine develops—and what it leaves largely untrained.

Looking at your own routine

When I looked at my own training, mileage was easy to see. Strength had no equivalent place in the picture.

Looking at a routine this way can be revealing. What do you practice regularly? What do you track? And what have you assumed was covered simply because you exercise?

Those questions do not make the work you already do less valuable. They can help you see it more clearly.

Keep the miles. Add the missing question.

I do not regret being a runner. I regret how long it took me to recognize that the habit I had built did not resolve the habit I had avoided.

That is the question I wish I had asked sooner: what is my training helping me do, and what am I assuming it covers?

You may find a different answer in your own routine. The point is to look closely enough to ask.