This article is for informational purposes only and does not replace advice from a trainer or doctor. HIIT is demanding on the cardiovascular system — if you have heart or vascular conditions or have been inactive for a long time, consult a doctor before starting.
HIIT (High-Intensity Interval Training) is a training method built around alternating short, very intense bursts of effort with periods of rest or low intensity. HIIT's popularity comes mainly from its time efficiency — short sessions can produce endurance results comparable to, or better than, longer moderate-intensity training.
How a HIIT session is structured
A typical HIIT session consists of repeated cycles, for example 30 seconds of maximal effort followed by 30-90 seconds of rest or slow pace, repeated 8 to 20 times. Total session time, including warm-up and cool-down, usually falls within 20-30 minutes.
How many calories HIIT burns
Because of its high intensity, HIIT burns a substantial amount of calories in a short time — roughly 300-450 kcal in a 30-minute session for a 70 kg person, depending on exercise selection and effort level. HIIT also produces the so-called EPOC effect (excess post-exercise oxygen consumption), so the body burns somewhat more calories for several hours after the session.
HIIT vs. steady-state cardio — differences
- Duration — HIIT is usually shorter (20-30 minutes) than steady-state cardio (45-60 minutes), for a similar endurance effect.
- Intensity — HIIT requires near-maximal effort during work intervals, which places greater strain on the cardiovascular and nervous systems.
- Recovery — the body needs more time to recover after HIIT than after moderate cardio, so daily HIIT sessions aren't recommended.
- Accessibility — steady-state cardio is usually easier to sustain for longer periods for beginners or people with health limitations.
Sample HIIT workout for beginners
After a 5-minute warm-up: 20 seconds of intense effort (e.g. jumping jacks, mountain climbers) and 40 seconds of rest, repeated 8 times (8 minutes total), followed by 5 minutes of cool-down and stretching. This short protocol is a safe way to get familiar with the HIIT format before progressing to more demanding variations.
Who HIIT isn't the best choice for
People new to physical activity, those with cardiovascular disease, recovering from injury, or in rehabilitation should be cautious and discuss introducing HIIT with a doctor or physiotherapist. High-intensity training isn't always the right starting point.
Calculate how many calories you'll burn in a HIIT session: Calories burned calculator →
Frequently asked questions about HIIT training
Is HIIT more effective than regular cardio?
HIIT can produce comparable or slightly better endurance results in less time, but it's not simply "better" — the right choice depends on your goals, fitness level, and preferences.
How often can you do HIIT per week?
Due to its high intensity, 2-3 sessions a week are usually recommended, with rest days or light activity in between to avoid overtraining.
Is HIIT suitable for beginners?
Yes, but in a gentler form — shorter work intervals and longer rest periods. People who are completely inactive should build a basic fitness base first.
How long should a single HIIT session last?
A typical session lasts 15-30 minutes including warm-up and cool-down. Longer sessions at such high intensity are hard to sustain and increase overtraining risk.
Can you do HIIT without equipment?
Yes, many popular HIIT protocols rely entirely on bodyweight exercises such as jumping jacks, jump squats, or mountain climbers.
Does HIIT build muscle mass?
To a limited extent. HIIT mainly develops endurance and muscular stamina, but it doesn't replace classic strength training with progressive overload for building substantial muscle mass.
Is the EPOC effect after HIIT significant for calorie burning?
The EPOC effect (excess post-exercise oxygen consumption) does increase total energy expenditure after a session, though its size is usually smaller than common belief suggests — the energy expenditure of the workout itself remains the most important factor.
Is HIIT safe for the heart?
For healthy, adequately prepared people, it's a safe form of training. People with cardiovascular conditions should discuss introducing HIIT with a doctor before starting.
Can HIIT be combined with strength training in the same week?
Yes, many people combine both types of training, but it's worth planning your days so you're not intensely training the same muscle groups without adequate recovery between sessions.
Does diet matter for HIIT training?
Yes, given the high intensity of effort, the body needs an adequate supply of energy and carbohydrates to perform successive work intervals effectively.