Interval training

Essentially, interval training is a workout where you exercise at different levels of intensity for different intervals of time or distance. It can be any type of exercise but we’ll be talking about running here. Interval running can be done at any pace depending on your fitness level and goals, but it’s usually associated with speedwork and is also known as high-intensity interval training (HIIT) or speed interval training.

Typically, a workout will comprise of a warm up, then repeated sets of running at a fast pace for an interval followed by an interval of running at a slower pace to recover. Once you’ve completed a certain number of sets, you do a cool down. If you started your running career with the Couch to 5K or a similar programme, you’ll be familiar with the principle - though you would have been doing sets of walking and running.

When you exercise regularly, your body responds by adapting to become more efficient at performing the exercise. Once your body has adapted to your level of training, you’ll start to see your performance plateau. By adding interval training to your schedule, your body will begin to adapt to the higher intensity of the hard intervals, bringing new benefits, including:

Building fitness

Interval training is one of the best ways to boost your fitness as it gets your body used to training at higher intensities. The irregular nature of intervals keeps your body guessing, so it doesn’t get accustomed to a routine and plateau.

So how does interval training improve cardiovascular endurance? The recovery interval is the key. Stroke volume - the amount of blood pumped by the left ventricle of the heart in one contraction - peaks during the recovery interval, so more intervals in your training means more stroke volume peaks. And the higher the stroke volume, the more your heart goes into overload, and the stronger it gets.

Expanding anaerobic capacity

Anaerobic capacity is the point at which your aerobic system can’t keep up with demand and your body turns to anaerobic metabolism to generate energy. This causes lactic acid build up in the bloodstream. Interval running forces your body to become more efficient at removing lactic acid, thus expanding your anaerobic threshold.

Improving running pace

If you’ve ever tried to improve your speed over distance, you’ll know it’s not as simple as just trying to run faster. Running a full 5K at a faster pace for example, is going to be tough. So how does interval training improve speed? It allows your body to adapt to the faster running pace of your high intensity intervals. By improving your anaerobic capacity, you’ll be able to run faster for longer.

Burning more calories

Interval training burns more calories than running at a steady pace due to the increased intensity of the exercise. But it’s not just during the workout that you burn more calories. Because of an effect known as excess post-exercise oxygen consumption (EPOC) or ‘after-burn’, you can also burn more for 16-24 hours post workout. This is because your body has to work hard to recover from the demands of intervals.

Mixing things up

Running the same training runs over and over can, dare we say it, get a little boring sometimes. Breaking up your routine with different types of interval runs can add interest and keep you engaged. Plus, pushing yourself in short bursts is a lot of fun and can give you an endorphin high.

Being more time efficient

Interval running packs a quality session into a short amount of time. So if you’re struggling to fit long runs into your busy schedule, try swapping one or two with interval sessions, and free up some time.

While interval training is a safe and effective way for most people to improve their running performance, as with all forms of exercise, it doesn’t come completely risk-free.

There’s no two ways about it, interval runs are tough. With increased intensity comes an increased amount of stress on the body and a greater chance of injury. There’s more impact on your ankles, knees, and hips during faster running, which can potentially lead to muscle pulls, strains, or tears.

There are a few things you can do to reduce the risk of injury:

• Don’t do too much too soon - your body will adapt better if you don’t overload it too quickly, and give it plenty of time to rest and recover. Start with one interval session a week and gradually build up to a maximum of three.

• Make sure you warm up and cool down properly - this is even more important than it is with a normal run.

• Listen to your body - if something hurts, stop. You shouldn’t be feeling any sharp pains or niggles during your runs, but do expect a bit of post-workout soreness.

• Wear the right running shoes - with more impact on your joints, it’s even more important that your running shoes are giving you the support and cushioning that you need. Our range of women's training shoes and men's training shoes has something for every type of foot.

With a whole world of interval training out there, finding where to start can be a bit overwhelming. There’s fartlek training, pyramid intervals, and tempo runs, along with specific interval training for marathons, 5Ks, and more. There are an infinite number of combinations of workout types, interval lengths, and numbers of sets. So, to make it easy for you, we’ve put together a few interval workouts for beginners. Once you’ve mastered them, the interval-training world is your oyster.

Simple session for your first few attempts:

• 5-min gentle warm-up jog

• 1-min fast interval (at 80-90% effort)

• 2-min recovery interval (jogging or brisk walking at 30-40% effort)

• Repeat 4-6 times

• 5-min gentle cool-down jog

A basic pyramid workout for when you’re ready for something a little more intense:

• 5-min gentle warm-up jog

• 1-min fast interval (at 80-90% effort)

• 2-min recovery interval (jogging at 30-40% effort)

• 2-min fast interval (at 80-90% effort)

• 2-min recovery interval (jogging at 30-40% effort)

• 3-min fast interval (at 80-90% effort)

• 2-min recovery interval (jogging at 30-40% effort)

• 2-min fast interval (at 80-90% effort)

• 2-min recovery interval (jogging at 30-40% effort)

• 1-min fast interval (at 80-90% effort)

• 2-min recovery interval (jogging at 30-40% effort)

• 5-min gentle cool-down jog

Training for a 5K? Here’s a session to help get you to your goal pace:

• 800m gentle warm-up jog

• 400m run at your goal 5K pace

• 400m recovery run

• Repeat run-recovery cycle 4 times

• 800m gentle cool-down jog

Not only is interval training a fantastic way to boost your fitness and speed, it’s an exciting way to shake up your training schedule. If you’re stuck in a running rut, it could be just what you need to get your mojo back. Our beginners’ guide has laid out all the information you need to take your first interval-training steps, all that’s left to do is for you to lace up your running shoes and get going.