Interval timer

How to use it

Set the three numbers, press Start. A ten second Prepare countdown gives you time to get into position before the first round.

The colour of the panel says where you are without your having to read anything: amber while you prepare, green while you work, blue while you rest.

Turn the sound on if you would rather listen than watch. There is a short beep for the last three seconds of every interval, and a different tone each time the phase changes.

Nothing is saved and none of your information is sent anywhere. The settings return to 35 seconds, 25 seconds and 10 rounds when the page is reloaded.

Why intervals

Short, hard efforts with a rest between them are an efficient way to raise fitness, and they help muscle take up glucose from the blood. The original Tabata protocol used 20 seconds of very hard work and 10 seconds of rest, repeated eight times. The defaults here are gentler and more forgiving, and every number can be changed.

The exercise you choose with this timer is up to you. Anything that gets you out of breath will do: stairs, a bike, squats, walking briskly uphill, press ups against a worktop. Use it with the 28 Day Plan.