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GUIDES

Work-to-rest ratios for interval training

How hard you go decides how long you rest. Common ratios, what they train and how to choose

Common work-to-rest setups
RatioExampleEffortUsed for
2:120 s / 10 sVery hardShort, intense finishers 3
1:130 s / 30 sHardGeneral HIIT and circuits
4:34 min / 3 min90 to 95% of max heart rateAerobic fitness 2
1:830 s / 4 minAll-outSprint intervals 1
1:21 min / 2 minHardBeginners and run-walk

How to choose

  • For all-out sprints, rest long enough to go all-out again. Short rest turns a sprint session into an endurance one.
  • For aerobic fitness, use longer intervals at a hard but steady effort, with somewhat shorter rest.
  • For beginners, start with more rest than work, and shorten it as your fitness improves.
  • Let your heart rate decide: Cero’s Adaptive HR can extend your rest until your heart rate falls below a target.
Free toolTry your ratio nowSet work, rest and rounds in your browser, free.

Sources

  1. Gibala MJ, Little JP, van Essen M, et al. Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. J Physiol. 2006;575(3):901-911. doi.org/10.1113/jphysiol.2006.112094
  2. Helgerud J, Høydal K, Wang E, et al. Aerobic High-Intensity Intervals Improve VO2max More Than Moderate Training. Med Sci Sports Exerc. 2007;39(4):665-671. doi.org/10.1249/mss.0b013e3180304570
  3. Tabata I, Nishimura K, Kouzaki M, et al. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Med Sci Sports Exerc. 1996;28(10):1327-1330. doi.org/10.1097/00005768-199610000-00018

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

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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.