What is interval training and is it right for everyone?

From the benefits to who can do it and how to get the most out of it for your body, here’s our expert guide

Interval training is suitable for everyone (The Independent)

Interval training has gained enormous popularity in recent years because it offers great results for health and fitness in a shorter time frame than other workouts if done right and with consistency. It can be incredibly varied because you can choose a mix of exercises that you enjoy doing and mix it up, rather than pushing yourself through a gruelling workout with a fixed set of movements. The best part? You can be done in 30 minutes or less.

Fitness experts love interval training because it’s suitable for every ability. Unlike something like Hyrox or CrossFit, it’s very accessible and you can do it at home, in the gym or in the park. Originally known as fartlek – a Swedish term meaning “speed play” – interval training uses a mix of high-intensity and low-intensity exercises to improve speed, strength and endurance.

We asked the experts how to do interval training, what the benefits are and how to get the most out of this practice, depending on your fitness level and health goals. Keep reading for everything you need to know.

What is interval training?

Interval training is a form of exercise that alternates between timed bursts of activity and timed recovery periods. Essentially when you train in intervals you’ll go through a cycle of maximum effort to lower-effort movements and then repeat. An example of this could be sets of exercises in the gym or a sport like football or basketball, in which a quick burst of energy will be followed with slower, more tactical movements that allow your body to recover before another big push.

High intensity interval training – also known as HIIT – is a workout style favoured by the likes of Hugh Jackman, David Beckham, Beyonce and Scarlet Johansson, to name a few. But high intensity isn’t the only way to go. There are lower-impact versions of this style of training that make it accessible to all fitness levels and abilities.

“Interval training offers a lot of great benefits for both experienced athletes and the average person, making it a fantastic way to approach a workout routine,” says Alasdair Nicoll, a personal trainer and tutor at The Fitness Group. “One of the biggest perks is how efficient it is. You can get the same, if not better, results from shorter bursts of high-intensity exercise mixed with rest periods compared to longer, steady workouts. This is perfect if you’re busy and need to squeeze in a quick, effective workout.”

With interval training, you can tailor your intervals to your fitness level and wellbeing goals, working up from shorter periods of activity with easier exercises and lighter weights to longer intervals with harder exercises and heavier weights. It really depends on what you’re trying to achieve but the beauty of this style of exercise is that it can be modified so that anyone can try it. Your couch to 5K app? That’s essentially a form of interval training.

International Fitness Training and Support Manager at Orangetheory Fitness Sean Johnson explains that “while it’s common in the gym, interval training can also be practised with running, cycling or swimming. It’s suitable for all genders, offering tailored intensity based on your fitness levels. But, it can be especially beneficial for women in midlife because of its effectiveness in maintaining cardiovascular health and muscle mass. For those with specific goals, it’s often recommended for weight loss because it increases metabolism and burns calories effectively. And for enhanced endurance and strength – it’s great for improving athletic performance and improving general fitness.”

While this type of training can be done with reps using machines in the gym, you can also practise it with weights at home, running on a track, in the park, on a treadmill, or in your local swimming pool. “This variety also helps you avoid hitting a workout plateau (when you don’t see any gains despite working out) and keeps you motivated to stick with it,” says Nicholl.

What are the benefits of interval training?

The technique is a great all-rounder for cardiovascular, aerobic and anaerobic fitness and it can also help with steadily increasing endurance. “Over time, interval training can help lower your blood pressure, improve your cholesterol levels and reduce your resting heart rate, all of which are great for your overall cardiovascular health. You’ll also find that both your aerobic and anaerobic fitness levels improve, making everyday activities easier and less tiring,” says Nicholl.

Interval training works both the aerobic and the anaerobic systems. During a few minutes of high-intensity exercise, the anaerobic system uses the energy stored in your muscles. This exercise causes lactic acid to build up and causes oxygen debt, which is what makes your muscles feel tired and sore.

Then the heart and lungs work together to make up the oxygen debt and break down the lactic acid. During this process, your aerobic system converts stored carbohydrates into energy, burning calories. The body responds with maximum efficiency to a quick burst of energy and a short rest, meaning you can train for longer without feeling as tired or sore as you would with a prolonged workout, run, swim or cycle.

“Interval training is amazing for burning calories and fat both during and after your workout, thanks to something called the afterburn effect,” explains Nicholl. “This means you keep burning calories even after you’ve finished exercising, which is handy for weight loss and improving body composition. Another bonus is that the varied nature of interval training can help reduce the risk of injuries. As it includes a mix of high and low-intensity activities, your muscles and joints get a chance to recover during the lower-intensity periods. This balanced approach helps prevent the overuse injuries that can happen with repetitive, high-impact exercises."

How to do interval training

If you’ve never tried interval training before, choose a series of exercises that you feel comfortable doing multiple reps of. Or choose something like running. “My advice for beginners would be to start slow and begin with moderate intervals, then gradually increase the intensity,” says Johnson.

“Always warm up and cool down before and after you train in this style. Stretch, do some breathing exercises and get your heart rate up before you dive in. It’s also essential to listen to your body. Don’t overtrain and make sure you take adequate rest. You’ll see better results this way and avoid injuring yourself.”

You can try a simple running exercise to begin with. For example:

• To warm up, do a gentle jog for about five minutes. 
• For your high-intensity interval, run for a minute and a half. 
• For your recovery interval return to a manageable jog for three minutes.
• Then repeat this four times.
• Finish with a cool-down of five minutes of walking. 

Depending on your fitness goals and level you can adjust the duration of your intervals, the speed at which you’re walking, running or jogging and the number of repetitions. You can also use wearables, such as fitness trackers, smart rings and fitness bands to monitor heart rate. If you have specific health goals, monitoring your glucose levels at different intervals can also give you more in-depth insights into how your body is responding and how you progress as you keep training over time.

Johnson explains that “if you want to optimise your interval training remember that consistency is key. You should be doing regular sessions to see results. Variation can also help so try mixing different exercises to target various muscle groups. You can also look at other areas of health to support your training, for example, a balanced diet of adequate protein intake for muscle repair and carbohydrates for energy will yield better results with this kind of training. And adequate sleep and stress management are crucial.”

Looking for tips on starting running? Read our beginners’ guide to running a half marathon, according to experts