HIIT: How To, Form & Muscles Worked

Perform repeated short bouts of very intense effort followed by brief recovery to rapidly raise heart rate and stress the cardiorespiratory system.

How to do the HIIT#

Start with a 5–10 minute warm-up of light movement to prepare your heart and muscles.
Choose an interval scheme (for example 20–30 seconds hard, 40–60 seconds easy) and set a timer.
Execute each high-intensity interval at near-maximal effort using any dynamic movement you prefer.
Use the recovery periods for easy movement or rest so your breathing partially recovers before the next burst.
Finish with a 5–10 minute cool-down of gentle activity and stretching.

Muscles worked#

Primary: Quads (Quadriceps Femoris), Glutes (Gluteus Maximus)
Secondary: Hamstrings (Biceps Femoris, Semitendinosus & Semimembranosus), Calves (Gastrocnemius & Soleus), Abs (Rectus Abdominis)

Common mistakes#

Skipping the warm-up and starting full speed immediately.
Sustaining maximal effort for too long and burning out early.
Letting form deteriorate during intense intervals.
Not taking sufficient recovery between intervals.
Skipping the cool-down after the workout.

Frequently asked questions#

What muscles does the HIIT work?

The HIIT primarily works the quads, glutes. The hamstrings, calves, abs assist as secondary muscles — they stabilise the movement and take over when the main target fatigues. If you feel it mostly in the hamstrings, calves, abs, lighten the load and slow the lowering phase.

What equipment do I need for the HIIT?

None. The HIIT is a bodyweight exercise, so all you need is enough space to move through the full range of motion.

Is the HIIT suitable for beginners?

Not as one of your first exercises. The HIIT is rated intermediate, so it suits lifters who already have a few months of consistent training behind them. Build the pattern on an easier variation first, then come back to it.

What are good alternatives to the HIIT?

Aerobics, Bear Crawl, Bear Crawl Hold all train the same primary muscles as the HIIT. Pick whichever one matches the equipment in front of you.