GUIDES

Interval training guides

What the research says about HIIT, Tabata, rest and heart rate, with the studies behind it

These guides explain what published research says about interval training, so you can set up your timers with a reason behind every number. Each one lists the studies it relies on.

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Bring the effort.
We’ll keep the time.

Cero is free to download for iPhone, iPad and Apple Watch.

Download Cero
Cero’s interval builder on iPhone 18 Pro, with the template picker, warm-up, work, recovery and cool-down intervals, and per-interval timing controls

Cero is a timer, not a medical device. If you’re new to hard exercise, are pregnant or have a health condition, check with your doctor first, and stop if you feel unwell.