Interval training and the HIIT workout: how to use it well

0 to Elite course · Lesson 61 of 100 · Level 3: Novice to Intermediate

HIIT is one of the most hyped tools in fitness. Used well, it builds fitness quickly. Used badly, it leaves you sore, tired and lifting worse. This lesson shows you how to fit it into an intermediate plan.

What a HIIT workout actually is

HIIT stands for high-intensity interval training. You alternate short bursts of very hard work with periods of easy recovery. A true interval is hard: by the end of each one you should be breathing heavily and unable to say more than a word or two.

That is different from a 45-minute class where you move quickly the whole time. Those sessions are often moderate work done for a long time, which is useful, but it is not really interval training. Real HIIT is short because it is hard.

In lesson 30 you built a base of easy cardio. That base matters. Intervals sit on top of it, they don’t replace it.

Why intermediates use intervals

• Time efficiency: a 15 to 20 minute session can noticeably improve your fitness.
• Higher top-end fitness: intervals push your heart and lungs harder than steady cardio, which helps you recover between heavy sets and keep up in sport.
• Variety: they break up the routine if steady cardio bores you.

What HIIT is not is a fat-loss shortcut. Fat loss comes from your overall calorie balance, and HIIT burns roughly what you would expect for a short session. If fat loss is your goal, read the full guide to the best cardio for fat loss and our comparison of cardio vs strength training for fat loss.

How much HIIT you need

For most people who lift three or four times a week, one or two interval sessions a week is plenty. More than that and recovery starts to suffer, because intervals stress your legs and nervous system in a similar way to heavy training.

Some simple rules:

• Keep intervals away from the day before heavy squats or deadlifts.
• Do them after lifting or on a separate day, never before a heavy session.
• Keep most of your cardio easy. A mix of lots of easy work and a little hard work is the pattern you will build on in lesson 81 on Zone 2 and VO2 max.

Three simple HIIT sessions to try

Use a low-impact machine to start: an exercise bike, rowing machine or air bike. They are easier on joints than sprinting and easy to stop safely. Warm up for 5 to 8 minutes of easy work first, as you learned in lesson 11.

Session 1: the starter

30 seconds hard, 90 seconds easy. Repeat 6 times. Cool down for 5 minutes.

Session 2: the classic

1 minute hard, 1 minute easy. Repeat 6 to 8 times. Aim to keep each hard minute at a similar output, so pace the first one.

Session 3: longer intervals

3 minutes hard (hard but sustainable), 2 minutes easy. Repeat 4 times. This builds the fitness that helps you recover between sets.

Rate each hard effort using the RPE scale from lesson 25. Hard intervals should feel around 8 or 9 out of 10, never an all-out sprint that leaves you dizzy.

How to progress and common mistakes

Progress one thing at a time: add one interval, then shorten the rest slightly, then increase the output on the machine. Write it in your training log like any lift.

Common mistakes:

• Going all out from rep one and fading badly by rep three.
• Doing HIIT every day and wondering why your lifts stall.
• Choosing complex lifts for intervals, such as fast barbell work. Technique breaks down when you are out of breath. Keep it to simple machines or bodyweight moves.
• Skipping the warm-up and cool-down.

Safety: HIIT puts a big demand on your heart. If you have a heart condition, high blood pressure, are pregnant, or get chest pain, unusual breathlessness or dizziness during exercise, stop and speak to your GP before doing intervals. Revisit lesson 4 on health checks.

Your action steps

1. Pick one low-impact machine you are comfortable on and do Session 1 this week, after a lifting session or on a rest day.
2. Rate each interval with RPE and note it in your training log.
3. Plan where your one or two weekly interval sessions go, keeping them away from the day before heavy legs.
4. Keep at least two easy cardio sessions or daily walks in your week alongside the intervals.
5. After two weeks, progress by adding one interval or shortening rest slightly.

Frequently asked questions

How many times a week should I do a HIIT workout?

For most people who also lift weights, one or two interval sessions a week is enough. More than that tends to hurt recovery and strength progress.

Is HIIT better than steady cardio for fat loss?

Not really. Fat loss depends on your overall calorie balance. HIIT saves time, while easy cardio is easier to recover from, and most people do best with a mix.

Can beginners do HIIT?

Beginners should build a base of easy cardio and good lifting habits first. Short, gentle intervals on a bike can come later, and anyone with a health condition should check with their GP.

Keep going

Previous: Lesson 60: Accessory Exercises: What They’re For and How to Choose Them

Next: Lesson 62: How to set up a cutting phase without losing muscle

Lost your place? See the full course map.

Want Artem to coach you through it? SYP Fitness is a private 1-to-1 personal training studio at 2-4 Navigator Square, Archway, London N19 3UB. Rated 5.0 from 106 Google reviews. Book a free consultation or WhatsApp Artem on 07301 512215.