I cringed a little when I first saw it.

During the week, the social media posts were flooding in - all with variations of the same message:

Exercise intensity trumps volume.

And I thought to myself, here we go again…

This isn’t the first time new research has led to claims exercise at higher intensities - or training harder - matters most for health benefits.

But this message is problematic for a few reasons.

Not to mention this conclusion isn’t really what the data from this study shows...

So let’s dive into why that is, and why you don’t actually need to train harder for more benefits.

What the study actually looked at

The study in question was published this week in the European Heart Journal.

Like many similar observational studies, it used data from the UK Biobank that captured physical activity measures from over 90,000 adults using wrist accelerometers.

This allowed the authors to assess both total physical activity (or volume), and the proportion of activity done at a higher (vigorous) intensity.

From there, the authors looked for associations between these factors and the incidence of various chronic diseases, including heart disease, type 2 diabetes, dementia, as well as all-cause mortality over a period of around 9 years.

Now the headline conclusion was those who accumulated a higher proportion of vigorous activity tended to have lower disease risk, even when total activity levels were accounted (or controlled) for.

So at first glance, this seems to suggest intensity matters more than volume.

But the reality is there is more nuance to this conclusion - and here’s why.

Total activity still matters most

Looking at the data, total activity is still important.

There was a strong association between total activity levels - regardless of intensity - and health outcomes.

Across the study, people with higher overall physical activity had lower risks of cardiovascular disease, diabetes, dementia and death, even before considering how much of that activity was vigorous.

A great example of this is the figure below for type 2 diabetes:

Even at the same proportion of vigorous activity (shown along the bottom axis) - let's say 3% as indicated by the red dotted line - people who simply accumulated more total activity, as indicated by the different curves, had lower risk.

This reinforces the message that just moving more is important.

Why this isn’t really intensity vs. volume

Within a given total amount of activity, as intensity goes up, something else must come down (and vice versa).

The way intensity was calculated in this study meant the two are partly linked, and can’t be completely separated.

In this study, intensity was first classified using accelerometer movement thresholds (for example, vigorous activity was defined based on higher acceleration levels).

Total volume was then calculated using MET-minutes, which weights vigorous activity more heavily than moderate or light activity.

And because vigorous activity contributes more to total MET volume by definition, intensity is partly built into the volume measure itself.

What the study really showed was this:

For a given level of physical activity, replacing some with vigorous intensity activity was associated with lower disease risk.

As an example, compared to those doing no vigorous activity, those whose activity included more than about 4% vigorous intensity had around 30–60% lower risk of several major chronic diseases, depending on the outcome.

Importantly, this didn’t require large amounts of vigorous exercise - just a small proportion of total activity.

In practical terms, if someone was doing 150 minutes of activity per week, this could mean replacing just 5-10 minutes with something like brisk hill walking, short cycling efforts, or brief faster intervals during a walk.

Which brings me to the next point.

Intensity depends on the individual

Exercise that’s hard for me, may not be so hard for you.

When I go for my weekly longer run with my running buddy, we’ll run at the same pace - but my heart rate is sitting at 150+ beats/min while he’s cruising along at 130 (we’re about the same age, so theoretically our maximum heart rates are similar).

So we’re running at the same absolute intensity (speed), but in a relative sense, I’m pushing harder than he is.

That’s the difference here. But that’s not how the study treated intensity.

In large population studies like this, intensity is usually defined using absolute movement thresholds, rather than how hard the activity feels for each individual.

In this study, vigorous intensity was defined using accelerometer movement thresholds, which broadly corresponds to activities requiring ≥6 METs.

In practical terms, this equates to things like jogging, brisk uphill walking, faster cycling, or stair climbing - not just maximal effort exercise.

This means what is classified as “vigorous” may actually feel moderate for someone who is very fit, while the same thing could feel very hard for someone who’s less conditioned, older, or has a chronic health condition.

The point is, the intensity threshold that mattered here was likely far more achievable than the headlines suggest.

The real take-home message

Let’s get back to some of the conclusions many have drawn from this study:

“The health benefits of exercise depend heavily on intensity.”

“High intensity can’t be compensated by duration.”

“This speaks in favour of hard, short intervals”.

These messages are misleading for the reasons I’ve discussed, and possibly harmful for the everyday person who wants to improve their physical activity levels for health reasons.

That’s why the real message is that BOTH intensity and volume (amount of activity) matter.

But importantly, consistency matters most.

So for most people, the early focus is just moving more - which means intensity is less important.

From there, a little more intensity can be added into the mix.

So it’s really about intensity alongside adequate volume - not the reverse.

What you should do instead

This isn’t the first study to claim intensity is superior.

And look, there’s no doubt intensity is important.

But it’s more important when you can first accumulate a higher level of general activity, however light or simple it might be.

The risk of emphasising intensity too early may be obvious - but it almost certainly increases the risk of making your routine unsustainable because of injury, excessive fatigue, or just because you’ve made yourself believe exercise has to be downright unpleasant.

So here’s what you should do instead.

Focus on doing a little more first. The easiest way to do this is to prioritise how often you engage in activity during the week. So you’re not exercising for longer, but you’re doing it more often.

Then, as you prove to yourself you’re an active person who shows up often, you can start to add more duration.

And from there, you can add the cherry on top, which is some higher-intensity work.

Get this balance right and you’ll benefit from exercise for decades - not just a few weeks.

Once again, thanks for reading!

PS: I’d love to hear from you: What do you tend to default to - getting enough total activity in, or trying to add intensity? Hit reply and let me know!

Until next week,

Jackson

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IMPORTANT:

The information contained herein is of general nature only and does not constitute personal advice. You should not act on any information without considering your personal needs, circumstances, and objectives. Any exercise program may result in injury. We recommend you obtain advice specific to your circumstances from an appropriate health professional before starting any exercise program.