Tabatas save the day when you think you simply can’t get your workout in. In its simplest form, a tabata consists of 20 seconds of maximal effort and 10 seconds of rest, repeated for eight rounds. They’re simple and effective, and you can do them anywhere, anytime, with no equipment. Best yet, there are endless tabata combinations you can create.

This highly effective form of high intensity interval training is named after the Japanese exercise physiology researcher, Dr. Izumi Tabata, who experimented and wrote extensively on the training system developed by speed skating coach Irisawa Koichi. The system worked so well on the skaters that it has become a training staple for improving both anaerobic capacity and aerobic capacity in athletes at all levels.

You can turn just about anything into a tabata — from front squats to double-unders. Here are a few ideas for tabatas you can do anywhere, with no equipment. You can do them individually or combine multiple movements into one tabata.

1. Squats

Either hold the mid/deep squat position for the 20 seconds, or perform repetitions of squats for 20 seconds. Too easy? Perform jumping squats to add a layer of difficulty.

2. Alternating Planks

Perform a plank hold for 20 seconds. If that is too easy, try holding side planks and alternating right and left sides each round. You could also add weight to any of these to make them harder.

3. Hollow Body

Holding a hollow body for 20 seconds is more difficult than you might think. Try a hollow body rock to add difficulty. To ease up, alternate between a classic hollow body and right/left hollow body positions.

4. Plank-to-Push-Up

Start in a plank position, then lift up into a push-up position with arms extended. Perform repetitions for 20 seconds and then rest, or use the 10 second rest time to hold a plank for extra difficulty.

5. Jumping Lunges

Work your legs and glutes with alternating jumping lunges. If you are unable to complete all rounds consistently, switch to lunges or walking lunges to keep working.

6. Swimmers

This is a great variation of supermans and is one of the few bodyweight exercises to work the postural muscles of the back and shoulders (extensors). Starting in a superman position, kick your legs and perform a breaststroke as if you were swimming. Supinate the hands at the front position to have palms up and then finish the strokes with hands touching, pronated (also facing up) behind your back.

7. Tabata Sprints

The classic tabata is a sprint. Run all out for 20 seconds, then gently jog or walk for the 10 seconds of rest. Running intervals on the beach is a guaranteed challenge with some great results at the end. If you cannot run, try cycling.

8. Burpees

We couldn’t leave these out! Tabata burpees are a great way to get a killer full body workout in four minutes. Work legs, core and upper body along with your aerobic fitness with this classic. Aim to keep moving for all 20 seconds. It’s better to move slowly than to stop completely, so find a good pace and work within that zone.