Interval running: gain the benefits in less time

Running delivers a wide range of benefits. This popular form of exercise can help prevent disease, support mental health and may even slow biological ageing.

Yet roughly 31% of people do not take part in enough regular physical activity, including running. A shortage of time is the obstacle to exercise mentioned most often.

But what if it were possible to gain running’s benefits in far less time? That is the purpose of interval running.

Interval running and HIIT

Interval running is a type of high-intensity interval training (HIIT). Although HIIT has existed for nearly 100 years, it became widely popular during the 1990s and 2000s through sessions such as Tabata – 20 seconds of intense activity followed by ten seconds’ rest – and CrossFit, a demanding workout combining weightlifting, gymnastics and cardio.

The central principle of HIIT is to alternate short spells of very hard exercise with recovery periods or lower-intensity activity. In a typical HIIT session, for example, you might do burpees at maximum effort for 30 seconds, rest for 30 seconds, then repeat the exercise several times.

These HIIT principles can be incorporated into ordinary runs for people who want the workout’s rewards in a shorter period.

With the "10-20-30 method", for example, runners begin with 30 seconds of jogging or walking, continue with 20 seconds of moderate-paced running, and finish with a ten-second sprint.

Another straightforward introduction to interval running is the "fartlek" approach – Swedish for "speed play". Rather than jogging continuously at one pace, this method involves adding several sprints to the run.

The benefits of intervals

HIIT-based interval running can offer many advantages for the cardiovascular system, metabolism and body composition – the amount of body fat you carry and where it is stored.

Research involving people who were overweight or obese, for instance, found that sprinting produced larger improvements in one particular measure of cardiovascular fitness than running continuously at a steady pace. Participants completing sprints improved their V̇O₂ max more – the amount of oxygen the body can use to power intense activity.

Among people who already ran regularly, a 12-week trial showed that combining HIIT sessions with a weekly endurance run over 12 weeks improved V̇O₂ peak more than longer continuous runs did.

V̇O₂ peak is an indicator of cardiovascular fitness and cardiovascular capacity. Higher V̇O₂ peak supports performance and is also associated with a lower risk of death from any cause.

Studies also indicate that interval walking and running affect metabolic health more strongly than continuous walking, particularly by helping regulate blood glucose levels. This may reduce the risk of type 2 diabetes.

Compared with continuous exercise, HIIT workouts such as the 10-20-30 method have a greater impact on mitochondria, the energy-producing components of cells. The result is greater endurance and a lower risk of diabetes and cardiovascular disease.

The 10-20-30 method can also lower "bad cholesterol" and blood pressure more than continuous running. This in turn reduces cardiovascular disease risk.

Finally, while continuous running and HIIT can both lower visceral fat – the harmful fat surrounding the organs – HIIT achieves this more efficiently in terms of time.

In all these cases, the benefits can be achieved in a fraction of the time required by a conventional run. Sprint interval sessions lasting as little as 18 minutes, performed three times weekly, can produce health benefits.

How to get started

There are several ways to begin if you would like to try interval running.

When running outdoors, try sprinting between one lamp post and the next. Then walk or jog to the following lamp post to recover before sprinting again. This is one form of fartlek training.

At the gym, intervals can be performed on either a non-motorised treadmill or a standard motorised treadmill. The latter often includes selectable interval-training programmes, allowing you to alternate sprints and recovery periods. Walking intervals are possible too.

Sprints may last from only a few seconds to a couple of minutes. For the greatest benefit from interval running, aim to bring your heart rate towards 90% of its maximum during the "intense" phase. Make sure you recover adequately between sprints.

Building interval running safely

As with every exercise plan, activity levels should be increased gradually.

If you have been inactive for several years, going straight into interval running is unlikely to be advisable.

It is also wise to speak with your GP before beginning a new exercise regime, especially if you have a medical condition. HIIT may raise blood sugar levels, for example, causing hyperglycaemia in people with diabetes, so they should certainly consult their doctor before trying it.

A useful starting point is to include several sprints in your next run, each lasting from a few seconds up to a minute. You will probably begin to notice benefits within two to three months.

Alternatively, if sprints do not appeal, use the "10-20-30" method while running or try "Jeffing" – the run a bit, walk a bit method.

Even occasionally raising the intensity of your runs by a small amount can bring numerous health and fitness benefits.

Christopher Gaffney, Senior Lecturer in Integrative Physiology, Lancaster University

This article is republished from The Conversation under a Creative Commons license. Read the original article.