Tabata done right, and why your reps should fade

Short answer: a Tabata is eight rounds of 20 seconds as hard as you can go, with 10 seconds of rest after each, four minutes in all. Done right, it's hard enough that your reps drop off in the last rounds. That drop isn't failure. It means you worked at the right effort, so judge the session by whether your form held, not by whether round 8 matched round 1.

Where Tabata comes from

The name comes from a 1996 study led by Izumi Tabata in Japan. Seven people rode a stationary bike set to a fixed, very high workload, about 170 percent of the workload that matched their maximum oxygen use. They rode 20 seconds on and 10 seconds off until they couldn't keep the pedals turning fast enough. That took seven or eight rounds.

They trained this way for six weeks: four hard days a week, plus a fifth day of 30 minutes of steady riding followed by four rounds. Their aerobic fitness went up by about 7 ml/kg/min, and their capacity for short, all-out work went up by 28 percent. A second group rode at a moderate pace for an hour, five days a week. Their aerobic fitness improved too, but their all-out capacity didn't change much (Tabata and colleagues, 1996). It was a small study.

Two details matter for you:

The workload was set so people couldn't keep it up for all eight rounds. Fading was built in. As they got fitter, the workload went up so they still gave out around round eight.
It was done on a bike, where you can push very hard without much risk when you tire. Many "Tabata" classes use burpees or squats at a pace you could keep up all day. That can be a good workout, but it's a different one. Tabata himself has written that the original was a fixed, very high workload, not an all-out sprint, and that there's little research yet on versions using running or bodyweight moves (Tabata, 2019).

Why your reps should fade

If you do 15 squat jumps in round 1 and 15 in round 8, you weren't working as hard as the format asks. At real Tabata effort, 10 seconds isn't enough to recover, so each round starts a little more tired than the last.

An honest Tabata might look like this:

Round	1	2	3	4	5	6	7	8
Squat Jumps	14	13	12	12	11	10	10	9

Those numbers are an example, not a target. What you want is a steady slide with good form to the end.

The number to track is your weakest round. If it goes from 9 to 10 over a few sessions, you're getting fitter, even though round 8 is still lower than round 1.

Picking a movement

Pick something you can push very hard on without much risk when you're tired. From most forgiving to most demanding:

Machines: an air bike, a stationary bike, a rower or a ski machine. Effort goes up and down with you, and your form rarely breaks.
Simple bodyweight moves: fast Bodyweight Squats, Step-Ups, Mountain Climbers.
Harder bodyweight moves: Squat Jumps, Burpees, fast Push-Ups.
Kettlebell Swings, once you've learned the swing at an easy pace.

Skip complex lifts and heavy weights. When you're out of breath, technique slips first on the hardest movements. Use one movement for all eight rounds, or two that take turns. Three is too many to give each one a real effort.

A Tabata session, start to finish

Warm up for about five minutes. Start easy, then build. Finish with a few short, faster efforts of your movement.
Eight rounds: 20 seconds as hard as you can with good form, then 10 seconds of rest. On a machine, push as hard as you can. With bodyweight, do as many clean reps as you can.
Cool down for about two minutes at an easy pace until your breathing settles.

The whole thing takes about 11 minutes. Write down your reps or the machine's number for each round, or at least your weakest round.

Did your form hold?

At the end, ask one question: did my form hold to the end?

Form held, and your weakest round went up (or held steady two sessions running): go a little harder next time, with more resistance, a heavier kettlebell or a harder version.
Form broke in the last rounds once: keep everything the same next time. One rough day isn't a trend.
Form broke two sessions in a row: go lighter or pick an easier movement.
You could still talk easily at the end: you weren't at Tabata effort. That's fine for a day, but count it as an easier session.

How often to do it

The study used four hard days a week, but that was six supervised weeks with seven people. For most people, one or two Tabatas a week is plenty, with at least a full day between all-out sessions. Tabata adds to your strength training and easy cardio. It doesn't replace them.

Timing matters too. Hard cardio in the hours before a heavy squat or hinge session can hurt your lifting. A pooled analysis of combined training found that the cost to strength gains depended on the type, frequency and length of the cardio (Wilson and colleagues, 2012). That research looked at gains over weeks, not the gap within a day, so treat four hours as a cautious rule of thumb: do your Tabata after lifting, or at least four hours before.

If you have heart disease or another health condition, or you get chest pain or unusual breathlessness when you exercise, check with your doctor before doing all-out work.

Common mistakes

Pacing yourself. Holding back so round 8 matches round 1 turns a Tabata into an easier interval workout.
Picking a movement you can't do tired. If your form falls apart by round 4, pick something simpler.

If all-out work doesn't suit you yet, an EMOM or easy cardio builds a base first. For another short all-out option, see REHIT.

How Axial Fit does it

Health questions first. Tabata opens once you've answered a short set of yes-or-no health questions. Every hard session shows one line under End: "Chest pain, faintness or feeling unwell: stop now."
Intervals come first. Without a bike or rower saved for REHIT, the hard day it suggests is Intervals, which start easier and step up. It suggests Tabata once you're handling the top step. You can choose a Tabata yourself any day.
A recommended movement. It picks one that suits an all-out effort from your equipment, such as an air bike, a rower or Bodyweight Squats. Swap lists only movements that suit an all-out effort. One movement or an alternating pair, never three. It suggests Kettlebell Swings only after you've done swings in two sessions, though you can pick them yourself.
The whole session on the clock. A five-minute warm-up, eight rounds of 20 seconds on and 10 off, and a two-minute cool-down: 11 minutes.
Fading never counts against you. At the end it asks, "Did your form hold to the end?" When your form held and your weakest round went up, or held twice, the next Tabata starts at your next weight or a harder version, and the setup says so before you start. A harder version comes with Keep, if you'd rather stay where you are. It goes lighter after your form broke twice in a row, or once if you could still talk at the end.
Spacing is advice. It suggests a full day between all-out sessions, and hard cardio after strength or at least four hours before it. In your first two weeks it suggests one hard session a week. If you start one inside those limits, it tells you once and leaves "Start anyway" to you.
Pain ends the session. It's recorded, and pain never makes the next session harder.
It counts as strength when the movement is a strength pattern. Swings, Squat Jumps, Bodyweight Squats, Step-Ups and fast Push-Ups count toward your strength week as well as cardio. Machines, Burpees and Mountain Climbers count as cardio.

Sources

Tabata I, Nishimura K, Kouzaki M, Hirai Y, Ogita F, Miyachi M, Yamamoto K, 1996. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Medicine and Science in Sports and Exercise, 28(10), 1327-1330. doi:10.1097/00005768-199610000-00018
Tabata I, 2019. Tabata training: one of the most energetically effective high-intensity intermittent training methods. Journal of Physiological Sciences, 69(4), 559-572. doi:10.1007/s12576-019-00676-7
Wilson JM, Marin PJ, Rhea MR, Wilson SM, Loenneke JP, Anderson JC, 2012. Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. Journal of Strength and Conditioning Research, 26(8), 2293-2307. doi:10.1519/JSC.0b013e31823a3e2d