Three 30-minute sessions a week: a complete plan for a full diary

The arithmetic of 90 minutes

The World Health Organization's 2020 guidelines recommend 150 to 300 minutes of moderate activity a week, or 75 to 150 minutes of vigorous activity, or an equivalent mix. In the mix, a vigorous minute counts roughly as two moderate ones.

Applied to three half hours, that gives three very different weeks.

• All moderate: 90 minutes. Sixty short of the minimum.
• All vigorous: 90 vigorous minutes, equal to 180 moderate ones. Within the range.
• Mixed, half and half: about 135 moderate-equivalent minutes. Close, but still short.

The calculator applies the same logic: it counts vigorous sessions double and mixed sessions at one and a half. It is a planning aid, not a measurement of what your body did.

The WHO guidelines also state that activity in bouts of any length now counts towards the total. That matters for the walking described further down. The wider picture of weekly targets is in how much exercise per week.

Strength is a separate box to tick

The same guidelines ask for muscle-strengthening activities involving all major muscle groups on two or more days a week. This is in addition to the aerobic minutes, not instead of them.

Three full-body sessions tick the box with a day to spare. A meta-analysis of 25 studies by Schoenfeld and colleagues found strong evidence that, when the total weekly volume is the same, training frequency does not meaningfully change muscle growth. You can spread the work over three short sessions rather than two long ones without losing anything. When volume was not matched, higher frequencies did slightly better, which is one more point in favour of three.

There is a further reason not to skip strength. In a meta-analysis by Momma and colleagues, muscle-strengthening activity was associated with the largest reduction in mortality risk, about 10% to 20%, at roughly 30 to 60 minutes a week, and combining strength with aerobic activity was associated with lower all-cause, cardiovascular and cancer mortality than doing neither. These are observational findings. Three sessions with a 15-minute strength block each give 45 minutes, inside that range.

What goes into the half hour

A template that fits most people and most equipment:

1. Warm-up, 5 minutes. Brisk walking or easy cycling, then a few slow squats, hip hinges and arm circles.
2. Strength circuit, 15 minutes. Four movements done back to back: a squat or lunge, a hinge such as a deadlift or hip bridge, a push, and a pull. Rest briefly and repeat. Choose a load you could lift two or three more times at the end of each set.
3. Harder block, 8 minutes. Intervals on a bike, rower or hill: for example, 30 seconds hard and 60 seconds easy, five or six times.
4. Cool-down, 2 minutes. Easy movement until your breathing settles.

The strength block can be built from the movements in strength training for executives. The harder block follows the formats in short, hard workouts.

Why the intervals earn their place

In 30 minutes, intensity is the lever that makes the week count. In a 2019 review, Campbell and colleagues found that interval training improves insulin sensitivity, blood pressure and body composition about as much as moderate continuous training.

That is not the same as saying it is twice as effective. For these risk factors the benefits are comparable, and the advantage of intervals is that they fit in less time. The NHS states that you can also meet the weekly target with several short sessions of very vigorous activity.

Not every session has to be hard. A sensible week has one harder interval block, one moderate one and one in between.

Closing the gap with walking

If your three sessions are mostly moderate, walking fills the rest. The NHS says a brisk 10-minute daily walk counts towards the 150 minutes, and describes a brisk walk as about three miles an hour.

Ten minutes a day adds 70 minutes a week. Added to 90 moderate minutes, that gives 160, which clears the minimum. Two short walks between meetings, or the walk from the car park instead of the nearest bay, are enough. More ideas are in daily steps.

Placing the sessions in your week

• Space them out where you can: Monday, Wednesday and Friday, or Tuesday, Thursday and Saturday.
• Put the session with the hardest intervals on a day without a key meeting first thing the next morning.
• On travel days, swap the planned session for the version in the hotel room workout.
• In a Dubai summer, keep outdoor intervals for the early morning or move them indoors.

The World Health Organization put its 2020 guidelines under the message "every move counts". The phrase is useful in practice: a session cut to 20 minutes still counts, and a walk still counts. A plan that tolerates bad weeks lasts longer than a perfect one.

Building up without getting hurt

If you have been inactive, start with the strength circuit and moderate efforts only. Add the interval block after three or four weeks, with fewer repetitions at first, and increase the effort gradually over the following weeks.

People with heart disease, uncontrolled blood pressure or symptoms on exertion, such as chest pain or unusual breathlessness, should get medical clearance before starting vigorous or interval training.

When three becomes two

Some weeks will not allow three. Keep two, both with a strength block, and walk every day. Habits are rarely lost to one short week; they are lost when a short week becomes the reason to stop. The guide to mental load and training explains why, and how to make the sessions automatic.

If you want a coach to turn these three slots into a programme that progresses, you can create your space in the Club.