I’m a fan of exercise, but the way it’s commonly prescribed for weight loss (regular, aerobic activity such as running, cycling or rowing) does not actually appear to be very effective for here. Though, of course, it might be good for other things such as protection from chronic diseases such as heart disease and type 2 diabetes, as well as perhaps being good for mood and self-esteem. Of course another thing exercise is good for is that it can help people be fitter and go faster.
In recent times I’ve become quite interested in a form of exercise that is often termed ‘high intensity intermittent exercise’ (HIIE) or ‘high intensity intermittent training’ (HIIT) (I’ll use ‘HIIE’ from her on). This form of exercise basically involved periods of intense, short-duration activity (such as sprinting), interspersed with periods of rest or low-level activity (such as slow jogging). There’s growing evidence that HIIE can, compared to ‘steady state exercise’ (such as running at a continuous pace) boost fitness and even fat loss, and do it in a time-efficient manner too.
In one study, women engaged in either HIIE or steady state cycling for 15 weeks. The steady state exercise involved 40 minutes of continuous exercise. In this study, HIIE came in the form of 8-second cycle sprints interspersed with 12-second rest periods, for a total of 20 minutes. Exercise sessions were performed 3 times a week [1].
Over the course of the study, individuals engaging in HIIE lost a total of 2.5 kg of fat. In contrast, the individuals who engaged in steady state exercise lost no weight at all.
Another interesting study included in the review compared HIIE with steady state exercise in subjects diagnosed with metabolic syndrome [2]. Half the group performed 4 minutes of exercise at 90 per cent maximum capacity followed by 3 minutes of ‘recovery’ exercise for a total of four cycles. The remaining individuals exercised continually at 70 per cent maximum capacity for a similar length of time.
Fitness increased in both groups, but rose by about twice as much in the HIIE group compared to the steady state exercisers. Also, HIIE was significantly more effective in reversing signs of metabolic syndrome.
I was interested to see a recent study regarding HIIE has been published [3]. In this study, 18 trained runner were randomized to one of two training regimes over 7 weeks.
1. regular, steady-state-based training
2. high-intensity intermittent exercise
Each session was made up of the following components:
1 km of warm-up
5 mins of ‘interval training’ where each minute is made up of running for 30 seconds at low intensity, 20 seconds at moderate intensity and 10 seconds at near maximal intensity
2 minutes of rest
This 7 minute block was repeated 3-4 times
The total exercise time for the HIIE runners was reduced by more than half compared to the steady state runners.
At the start and end of the study, all the study participants ran 1500 and 5000 metres time trials.
The steady state runners did not see an improvement in their times over 7 weeks. However, the HIIE saw reductions of 21 and 48 seconds respectively. They also enjoyed reductions in cholesterol (for what that’s worth) and blood pressure which were not seen in the other group.
This study adds to the growing body of evidence which shows that HIIE can be a relatively time-efficient way to derive health and fitness benefits from exercise. As with everything, it’s not for everyone. However, for individuals already used to exercise, employing some HIIE in their regime can often pay significant dividends in less time than traditional training.
References:
1. Trapp EG, et al. The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women. International Journal of Obesity 2008;32(4):684–691
2. Tjønna AE, et al. Aerobic interval training versus continuous moderate exercise as a treatment for the metabolic syndrome: a pilot study. Circulation 2008;118(4) 346–354
3. Petursson-Gunnarson T, et al. The 10-20-30 training concept improves performance and health profile in moderately trained runners. Journal of Applied Physiology, 3 May 2012
