Overweight? Don't just exercise more: spread it out better

And when one is overweight, wishes to improve their metabolic health, and above all to protect their cardiovascular health over the long term, this distinction becomes particularly relevant.

The same amount of exercise… but distributed differently

An intervention study looked at middle-aged adults who were overweight and who followed a high-intensity training programme over several weeks. The idea was straightforward: to compare two ways of organising a comparable amount of exercise.

In one group, participants concentrated their high-intensity training into a single day. In the other, the same type of work was spread across three days of the week. The protocol was based on four-minute intervals of intense effort interspersed with recovery periods.

In other words, in one case, a substantial training load is concentrated into a single day. In the other, the stimulus is distributed throughout the week. And this is where things become particularly interesting.

Losing weight is not the only goal

Both strategies can produce favourable effects, particularly on weight and body composition. But when we look at cardiorespiratory fitness, the distribution of training becomes especially important.

And this brings us to a measurement that I consider fundamental in preventive medicine: VO2max.

What is VO2max?

VO2max corresponds, in simplified terms, to the maximum amount of oxygen your body is able to use during intense exercise.

To keep your muscles working during effort, several systems must function together: your lungs must capture oxygen; your heart must be able to transport it; your circulation must deliver it to the tissues; your muscles must be able to extract it; and your mitochondria must be able to use it efficiently to produce energy.

VO2max is therefore far more than a number reserved for cyclists, runners, or elite athletes. It is a global indicator of your cardiorespiratory capacity. And it is precisely for this reason that it is of particular interest to me when we talk about prevention and longevity.

Your cardiorespiratory fitness also speaks to your future health

Numerous observational studies have shown a very strong association between low cardiorespiratory fitness and the risk of mortality.

In large cohorts, poor cardiorespiratory fitness has even been associated with a risk of mortality comparable to — and in some analyses greater than — that observed with several traditional risk factors such as smoking or diabetes.

This obviously does not mean that tobacco or diabetes become secondary concerns. It means something far more significant: cardiorespiratory fitness must itself be regarded as a genuine marker of health.

And this changes the way we think about exercise. I don't just want my patients to lose a few kilograms. I want them to become metabolically, cardiovascularly, and functionally more capable.

Because a scale doesn't measure your heart's ability to respond to exertion. It doesn't measure your respiratory capacity. It doesn't measure your muscle mass. And it certainly doesn't measure your VO2max. You can therefore significantly improve your health without all of these benefits being immediately visible on your scale.

Why might spreading out training sessions be more beneficial?

Imagine two people who perform a broadly similar amount of exercise each week. The first concentrates nearly all of their training into a single day. The second completes three sessions spread throughout the week.

On paper, their weekly volume may appear comparable. Physiologically, it is not exactly the same thing.

Each training session represents a stimulus to which the body must respond. The heart adapts. The muscles adapt. The mitochondria adapt. The peripheral circulation adapts. Then comes a recovery period during which some of these adaptations are built.

By spreading sessions throughout the week, we regularly expose the body to new stimuli, separated by recovery periods. This is one of the reasons why the frequency and distribution of sessions can become just as important as the simple total number of minutes of exercise.

And this is where high-intensity interval training becomes interesting.

HIIT — High-Intensity Interval Training — involves alternating periods of intense effort with recovery periods. Why does this method interest me? Because it makes it possible to produce a significant cardiovascular stimulus in a relatively short amount of time.

In certain individuals, and when correctly prescribed, HIIT can improve cardiorespiratory fitness and VO2max in a particularly meaningful way.

But be careful: high intensity does not mean unstructured training or systematically maximal effort. The intensity must be adapted to each person's starting level, age, any existing conditions, joints, and cardiovascular risk.

A sedentary 55-year-old patient with obesity, hypertension, or joint pain should obviously not start the same protocol overnight as a trained athlete. The goal is to create an appropriate physiological stimulus, not to put oneself in danger.

Three short sessions rather than concentrating everything into a single day?

This is probably the practical message I want you to take away. When your goal is health and longevity, don't only think: 'How many minutes did I do this week?' Also ask yourself: 'How did I distribute my physical activity throughout this week?'

If your schedule allows, it may be more beneficial to stimulate your cardiovascular system regularly rather than remaining completely sedentary for several days and trying to 'make up' for all your activity in a single session.

Three relatively short sessions spread throughout the week can be far easier to fit into daily life than one enormous weekly session. And above all, they create something fundamental: consistency.

Consistency is a message sent to your body

Our body adapts to what we regularly ask of it. If you regularly stimulate your muscles, they have a reason to maintain themselves. If you regularly engage your cardiovascular system, it has a reason to adapt. If you remain seated for almost the entire week, your body adapts as well — but to a sedentary lifestyle.

This is a fundamental concept. Exercise is not merely a calorie expenditure. It is a biological signal. And that signal influences your heart, your muscles, your mitochondria, your insulin sensitivity, your vascular function, and a large part of your physiology.

If you are overweight, do not make the scales your only indicator

This is a point I feel particularly strongly about. When someone starts exercising because they are overweight, the first question is almost always: 'How many kilos will I lose?' I would sometimes prefer the first question to be: 'What state will my body be in six months from now?'

Your weight matters. Your waist circumference matters. Your body composition matters. But so does your ability to climb several flights of stairs without getting out of breath. Your muscle strength matters. Your blood pressure matters. Your insulin sensitivity matters. Your cardiorespiratory capacity matters. And your VO2max matters.

Health can never be reduced to the number displayed on a set of scales.

So, how do you optimise your training for longevity?

The principle is actually quite simple: move often rather than rarely. Spread your physical activity throughout the week.

Ideally, combine several dimensions of training: cardiovascular work; periods of intensity adapted to your abilities; strength training; and above all, daily movement.

Because a workout session should not serve as an excuse to remain seated for the other twenty-three hours of the day. Walking, taking the stairs, getting up regularly, sometimes working standing up, and maintaining daily activity all remain essential.