People who say they don’t have time to exercise may need to find another excuse. Exercise and Nutrition Scientist Kathleen Alleaume explains how to use interval training to cut your workout time in half (or more!).

What is interval training?

While traditional cardio involves working for a sustained period of time without a rest, interval training (I.T.) is a form of cardio exercise that alternates periods of higher intensity work with periods of recovery (complete rest and/or lower-intensity work). While both types of cardio improve fitness, I.T. has a more powerful effect when it comes to increasing your overall strength and endurance. As an added bonus, it burns more kilojoules in less time, so you can shorten your work-outs!

Benefits of interval training

1. Reduces your overall workout time. ‘Less is more’ with interval training.
2. You’ll burn more calories. The more vigorously you exercise, the more energy you’ll burn.
3. Boosts your metabolism. Even when you’re sleeping, your body’s metabolic rate is elevated for hours after you exercise, which means you use more kilojoules overall.
4. Keeps boredom at bay. Pumping up your intensity in short bursts can add variety to your exercise routine.
5. Can help break through a weight loss plateau. A weight loss plateau can indicate that your exercise regime needs to change. Interval training is a great way to switch up your workout.

Putting it into practice

One of the great things about interval training is that there are no hard-and-fast rules about how hard or how long the intervals have to be. If you are new to I.T., start out slowly and gradually increase the intensity and length of the intervals as your fitness improves.

Walking

1. To warm up, walk at a leisurely pace for 5 minutes.
2. Transition into a brisk walk (at a pace where you are able to comfortably talk, but only just) for 30 seconds.
3. Slow back down to a leisurely pace for 5 minutes. Repeat as many times as you can within a workout.

Total time

Start with a 20-minute walk 2–3 times a week, then gradually build up to 45 minutes 2–3 times a week.

As your fitness improves, build up to a 1 minute ‘on’/ 1 minute ‘off’ routine.

Jogging

1. To warm up, jog at a leisurely pace for 5 minutes (a pace that causes an increase in your breathing and heart rate).
2. Transition into a 30-second sprint (a pace that causes you to ‘huff and puff’).
3. Transition back to the jog for 5 minutes. Repeat as many times as you can within a workout.

Total time

Start with a 20-minute jog twice a week, then gradually build up to a 30-minute jog twice a week.

As your fitness improves, build up to a routine where you jog for 5 minutes, followed by a 1-minute sprint.

Cycling

Either on a stationary or outdoor bike.

1. To warm up, cycle at a comfortable pace, on a low resistance, for 4 minutes. Make sure you can comfortably carry on a conversation.
2. Increase the resistance a few increments and cycle at the same pace for 4 minutes.
3. Decrease the resistance and continue cycling at a comfortable pace for 2 minutes. Repeat the cycle as many times as you can within a workout.

Total time

Start with a 20-minute cycle 2–3 times a week, then gradually build up to a 30- or 40-minute cycle 2–3 times a week.

Swimming

1. To warm up, swim (freestyle) for 2 easy laps/ 2 lengths of the pool.
2. Then swim 1/2 a lap (1/2 pool length) at a faster pace, followed by treading in deep water for 30 seconds. Finish swimming the remaining 1/2 lap.
3. Swim 1 lap/pool length at a fast pace. Rest at the shallow end of the pool for 1 minute. Repeat the entire cycle twice.

Total time

Start with a 20-minute swim 2–3 times a week, then gradually build up to a 30-minute swim 2–3 times a week.

To use your muscles in different ways, use a mix of backstroke, breaststroke and butterfly, or use fins or a kickboard to give your lower body an extra conditioning advantage.

As your fitness improves, you can alternate your rest periods at the shallow end of the pool with jogging on the spot for 30 seconds.

How do I know what intensity is right for me?

A simple way to determine which intensity is best for your level of fitness is to conduct a ‘talk test’.

During exercise you should experience an increased breathing rate, but you shouldn’t feel exhausted. If you’re unable to speak during exercise, your level of exertion may be too high – and you may not be getting enough oxygen to your muscles.

Over time, as your fitness improves, work towards alternating bursts of speed with a moderate (instead of relaxed) pace to get the most benefits.