HIIT workouts: high intensity interval training, made simple

HIIT, or high intensity interval training, means short bursts of hard effort followed by easy recovery, repeated several times. A typical HIIT workout takes 20 to 30 minutes with the warm-up, and the hard work inside it may add up to only 5 to 15 minutes. It builds fitness quickly. It does not replace a sensible diet.

What is HIIT?

You pick a movement, such as cycling, rowing or squats. You go hard for a set time, then slow right down for a set time, and repeat.

• Work interval: hard enough that you can only say a word or two.
• Rest interval: easy pedalling, slow rowing, walking or standing still.
• Rounds: how many times you repeat the pair.

A session is written as work and rest, for example “6 x 30 s hard / 90 s easy”. That means six rounds of 30 seconds hard and 90 seconds easy.

What the research says about HIIT

Exercise scientists have studied interval training for decades. Three findings matter for a gym member.

It saves time. A review in the Journal of Physiology found that low-volume interval training produces many of the same changes in muscle as long endurance training, “despite a substantially lower time commitment” (Gibala et al., 2012). One lab protocol in that review used 12 sprints of 30 seconds on a bike, far harder than a pace you could hold for a few minutes.

It raises fitness a little more than steady cardio. In a meta-analysis of 10 studies with 273 patients with lifestyle-related conditions such as high blood pressure, type 2 diabetes or obesity, peak oxygen uptake rose about 9.1% more after HIIT than after moderate continuous training (Weston et al., 2014).

It is not risk-free. In Norwegian cardiac rehab centres, 4,846 heart patients trained for 175,820 hours in all. There was 1 fatal cardiac arrest in 129,456 hours of moderate exercise and 2 non-fatal cardiac arrests in 46,364 hours of interval training (Rognmo et al., 2012). The risk was low in both, but higher with hard intervals. That was in heart patients under supervision, which is why the safety section below matters.

HIIT and fat loss: what to expect

HIIT burns calories, but so does a brisk 45-minute walk to Maitighar and back. Fat loss mostly comes from a small, steady calorie deficit.

• Use the calorie calculator to see roughly what you burn.
• Add strength training so the weight you lose is mostly fat. Our strength training guide covers the basics.
• Belly fat goes when overall body fat goes. No exercise targets one area. More on that in belly fat exercises.

3 HIIT workouts you can do at the gym

Each session starts with a 5-minute easy warm-up and ends with a 5-minute easy cool-down. Hard means about 8 out of 10 effort. Easy means you could hold a conversation.

1. Bike intervals (best for beginners)

The bike is kind to knees and easy to learn.

Week	Work / rest	Rounds	Hard time
1 to 2	30 s hard / 90 s easy	6	3 min
3 to 4	30 s hard / 60 s easy	8	4 min
5 to 6	45 s hard / 75 s easy	8	6 min

Raise the resistance for the hard part rather than spinning your legs wildly.

2. Rower intervals

Rowing uses legs, back and arms together. Learn the stroke first: legs push, then lean back, then pull the handle to your lower ribs. Ask a trainer to check your form in the first session.

Week	Work / rest	Rounds	Hard time
1 to 2	1 min hard / 2 min easy	5	5 min
3 to 4	1 min hard / 90 s easy	6	6 min
5 to 6	90 s hard / 90 s easy	6	9 min

3. Bodyweight circuit (no machines)

Good for days when the cardio machines are busy after office hours. Do each move for 20 seconds, rest 40 seconds, then go to the next move. One pass through all five is one round.

1. Squats (or sit-to-stand from a bench)
2. Push-ups on a bench or wall
3. Fast step-ups on a low box
4. Mountain climbers (or slow ones with hands on a bench)
5. Fast feet on the spot

Start with 2 rounds and rest 2 minutes between them. Build to 4 rounds over six weeks. Skip jumps if your knees complain.

How often should you do HIIT?

WHO advises adults to do 150 to 300 minutes of moderate activity a week, or 75 to 150 minutes of vigorous activity, or a mix, plus muscle-strengthening work on 2 or more days (WHO 2020 guidelines). Hard intervals count as vigorous.

A simple week for a beginner:

Day	Session
Sunday	Strength training
Monday	Bike HIIT
Tuesday	Brisk walk, 30 to 45 minutes
Wednesday	Strength training
Thursday	Rower HIIT or a Zumba class
Friday	Rest or walk
Saturday	Rest or a hike up Shivapuri if the weather is good

Never do HIIT on two days in a row when you are starting. If you feel flat for days, sleep badly or your legs stay heavy, drop a session.

Who should start slower

HIIT is not the right first step for everyone.

• New to exercise: build a base first with two to four weeks of walking and easy cycling.
• Heart condition, high blood pressure, chest pain, dizziness or fainting during exercise: see a doctor before you start HIIT. If you get chest pain, unusual breathlessness or a racing heartbeat during a session, stop and get checked.
• Diabetes: hard intervals can change blood sugar quickly. Ask your doctor how to adjust food and medicine.
• Joint pain or carrying a lot of extra weight: use the bike, not jumps or running.
• Pregnant or recently given birth: ask your doctor or midwife first.
• Winter smog days: if Kathmandu’s air quality is poor, train indoors rather than doing sprints on the ring road.

If you want something hard but with a skill to learn, kickboxing and boxing classes use the same work-and-rest idea in rounds.

Get help setting your intervals

A trainer can choose the right machine, check your form on the rower, and adjust the work and rest so you finish every round. See get fit with a trainer.