Interval training and HIIT pacing explained

What the original Tabata study tested

In 1996 Izumi Tabata and colleagues published a study in Medicine and Science in Sports and Exercise. Seven young men trained on an exercise bike five days a week for six weeks. Each session was 7 to 8 bouts of 20 seconds at about 170 percent of their VO2max, with 10 seconds of rest between bouts. Their aerobic capacity rose and their anaerobic capacity increased by 28 percent.

Two details are often lost. First, 170 percent of VO2max is an all-out effort, far harder than most people reach with burpees or squats. Second, it was a small study of trained subjects. A home "Tabata" is still a useful workout, but it is not the same experiment.

Work-to-rest ratios

Every interval session is defined by how long you work and how long you rest. Tabata is 20:10, a ratio of 2:1. Course material from the University of Queensland gives broad guidelines: short, very hard intervals need relatively long rests, while longer intervals at a lower intensity can work with rest periods of a similar length.

Rest lets you recover enough to make the next interval hard again. If your form falls apart by round three, the rest is too short for the effort you're giving.

Pacing a session

Good pacing means the last round looks like the first. Build the session in this order:

• Warm up first: about five minutes of easy movement before the first hard interval.
• Choose an exercise you can keep in good form when tired.
• Aim for an effort you can repeat in every round, not a sprint you can manage only once.
• Use Get ready (seconds) to have time to get into position.
• Cool down with a few minutes of easy movement afterwards.

Who should be careful

Mayo Clinic advises talking with a health care provider before starting HIIT, especially if you have a chronic condition such as heart or lung disease, diabetes or high blood pressure. It suggests building a base of moderate exercise first, so you can keep going for at least 20 minutes, and limiting HIIT to two or three sessions a week, not on consecutive days.

Building up over time

Start with a forgiving format such as 30/30 and fewer rounds. When it feels manageable, add rounds or switch to 40/20. Leave true Tabata efforts for when you are already fit. The timer's beeps and colours do the counting, so your attention can stay on form and breathing.