‘High intensity intermittent exercise’ looks like a time-efficient way to improve fitness and health

‘Aerobic’ exercises such as walking, running and cycling can undoubtedly have benefits for health and wellbeing, but as I’ve written about more than once, there is scant evidence these forms of activity do much in terms of weight loss. One reason for this is the fact that these activities, unless quite-intense and extended in duration, do not burn a whole lot of calories. Exercise can make us hungrier too. And some evidence suggests that increasing formal exercise can lead to us being more sedentary in the rest of our lives.

In recent weeks I have started to become interested in a form of exercise that appears to offer more potential for fat loss – ‘high intensity intermittent exercise’ (HIIE). This entails periods of relatively brief, intense exercise, interspersed with periods of rest or relatively rest. In the days when I was an avid runner, we used to call this sort of exercise ‘interval training’ (a version of this is known as ‘fartlek’). In those days my goal was not to lose weight, it was to improve my running speed. And boy did it seem to do the trick here. I remember one summer within a few short weeks taking my 7-minute mile pace down to just over 6-minute mile pace with some interval training.

HIIE is often performed on a stationary bicycle, though it is possible to use other forms of exercise such as running or rowing. One quite-often used regime (known as Wingate test) uses 30-second ‘sprints’ interspersed with ‘rest’ periods of 3-4 minutes. Usually 4-6 of these individual cycles will be completed per session. Total session time will be about 20 minutes.

It is certainly true that 30 seconds of high intensity sprinting is hard work for even highly trained individuals. Also, such intensity of exercise is not to be recommended for individuals who are relatively unfit or who have medical concerns that preclude hard exercise. An alternative is to reduce both the sprint and recovery times. One common protocol employs 8-second sprints, interspersed with 12-second rests for a total of 20 minutes (60 cycles).

I’m planning a post about HIIE as it relates to fat loss specifically. However, a recently-published study caught my eye which I felt was worth sharing.

The study took 47 boys and girls (average age 16) and randomized them to one of three exercise groups:

1. 20 minutes of continuous running at 70 per cent maximum capacity, three times a week.

2. Sprinting for 30 seconds followed by 20-30 seconds of rest repeated 4-6 times, three times a week.

3. No exercise (control)

The whole study lasted 7 weeks.

Both exercise groups saw, compared to the control group, significant improvements in a range of areas.

For the steady-state exercisers, improvements were seen in fitness, body fat percentage, BMI, insulin levels, and markers of blood clotting.

In the HIIE group, improvements were seen in fitness, systolic blood pressure (the higher of the two blood pressure readings), and BMI.

Both forms of exercise had benefits, in other words. But now let’s compared the total amount of time spent exercising in the two exercise groups.

For the steady-state exercisers this amounted to 420 minutes (7 hours).

For the HIIE group, total exercise time was 63 minutes (3 minutes of sprinting per session).

This study showed was that actually very brief periods of strenuous activity can reap significant health dividends. In short, HIIE looks a like a potentially very time-efficient way of getting health benefits from exercise.

HIIE is not for everyone. Someone who is quite-unfit, very overweight, and has a history of heart disease is probably not a candidate for HIIE. However, it may be that someone like this might progress to HIIE after improving base levels of fitness and health. Individuals should consult with a doctor or suitable health professional before undertaking a programme that includes intensive exercise.


1. Buchan DS, et al. The effects of time and intensity of exercise on novel and established markers of CD in adolescent youth. Am J Hum Biol 4 April 2011 [epub ahead of print]

11 Responses to ‘High intensity intermittent exercise’ looks like a time-efficient way to improve fitness and health

  1. Michael 8 April 2011 at 12:39 pm #

    I completely agree with this article, and have experienced first hand the benefits of sprinting sessions (both the health benefits and the time benefits) but I do think it’s a little misleading to compare 7 hours of steady state exercise to 63 minutes of HIIE.

    Surely it would be more transparent that the HIIE group spent 1 hour 45 minutes exercising: 30 secs sprint + 30 sec rest = 1 min, repeat 5 times = 5 mins, 3 x per week = 15 mins, 7 weeks = 1 hour 45.

    Yes ok, the actual exercise portion is only 63 minutes but the elapsed time between starting exercising and finishing exercising is more than this.

    Let’s recognise the benefits without overstating them.

  2. Steven Rice Fitness 8 April 2011 at 2:01 pm #

    It still is called interval training, and the more common term is HIIT- high intensity interval training. I teach it as circuit, going through 5 or 6 exercise stations, including treadmills but also floor exercises, weights, anything to create a short, demanding metabolic load.

  3. Feona 8 April 2011 at 4:53 pm #

    Anyone who’s been a Scout or Guide will recognize this kind of interval training as Scout’s Pace.

  4. Michael 8 April 2011 at 5:35 pm #

    I’ve also tended to like HIIT, but from my interpretation of your writeup it sounds as if in this study aerobic improved body fat percentage but not BMI, and HIIT improved BMI but not body fat percentage. If that be true, then aerobic would be better for preserving/enhancing muscle mass than HIIT. Is that what the study showed?? It’s certainly not what others have said/found/claimed about HIIT versus aerobic. So I’m a bit confused.

  5. Jake 9 April 2011 at 2:08 am #

    I think the same result could have been achieved if the sprinting group had done sprints only once a week.

    I only do sprints once a week and I achieved the same result as I did when I was running long slow distance of 40 miles a week.

  6. Tim 11 April 2011 at 6:37 pm #

    You might be interested in an article by Abbie Smith (graduate student in excercise physiology at the University of Oklahamona, USA) that appeared in the June 2008 edition of “Men’s Health.”

    Her findings (from an experiement consisting of 69 college students) on interval training (6 weeks of HIIE on a stationary bike, with subjects pedaling 2 minutes at 90-100% of MHR, resting for 1 minute, repeating 4 more times).

    The results after 6 weeks appear impressive. The subjects reportedly saw 18% improvements in oxygen consumption, amongst other benefits.

    I can personally confirm the benefits of this program, having utilized it every other day since coming across the article (I was a collge hockey player, so I took to HIIE like a duck to water).

    For anyone interested, I located a link to the article: http://www.suhaibwebb.com/islam-studies/kill-those-paratas-cardiovascular-interval-training-break-your-speed-limits/



  7. Pete 16 April 2011 at 6:36 pm #

    Dear Dr,

    how would you modify the exercise instructions in Waist Disposal in light of the benefits of HIIE?

  8. John Briffa 16 April 2011 at 7:03 pm #


    If someone is wanting to accelerate their weight loss, is feeling particularly motivated, and is fit and healthy enough (having got the go-ahead from a health professional), then he or she may add HIIE on top of the other recommendations to be found in Waist Disposal.


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