HIIT (high intensity interval training) is a type of exercise that involves several short bursts of high intensity (effort) activity. You alternate these with short bouts of light exercise. You can carry out a HIIT workout when cycling, swimming, walking, rowing or using a cross trainer, for example.
You can tell if you’re doing high intensity exercise if your breathing is much deeper and more rapid and your heart rate increases very quickly. You’ll find it difficult to hold a conversation while exercising at this level.
HIIT can help to improve your overall fitness. But one of its greatest benefits is that it doesn’t take very long to complete. So if you have a busy routine, it may be a good option for you.
HIIT may also be beneficial for your:
- heart and blood vessels (cardiovascular health)
- body weight
- insulin sensitivity – this is your body’s ability to control your blood sugar level
Exercise, such as HIIT, burns up calories. Even when you stop exercising, your body carries on burning calories to restore itself. HIIT is thought to enhance the way your body breaks down fat, both during and after exercise. Some research studies have shown that HIIT may also help to regulate your appetite.
HIIT may be beneficial for your cardiovascular health. It can improve your VO2 max score, which measures how well your heart, lungs and muscles use oxygen. Some research studies have shown that HIIT may improve how well your body controls its blood sugar levels. This is thought to be because your muscle cells adapt so they take up sugar for energy more easily.
It’s recommended that you do at least two sessions of HIIT per week.
In total, these exercises will take you 12.5 minutes to complete. It’s a good idea to start with a two- minute warm-up and end with a two-minute cool down at a ‘very light’ intensity. Use the exertion (effort) chart below to help you gauge what level this needs to be.
High intensity should be ‘very hard’ on the exertion (effort) scale. Low intensity should be ‘very light’ on the exertion scale.
Weeks Activity 1 to 3 15 seconds high intensity;
60 seconds low intensity
REPEAT X 10
4 to 6 20 seconds high intensity;
55 seconds low intensity
REPEAT X 10
7 to 9 25 seconds high intensity;
50 seconds low intensity
REPEAT X 10
10 to 12 30 seconds high intensity;
45 seconds low intensity
REPEAT X 10
In addition to the exercises above, aim to include a longer session of exercise in your routine. Ideally this will be a moderate intensity activity, such as brisk walking.
If you start to feel unwell, lightheaded or have severe shortness of breath, stop and sit down immediately. If you don’t feel better, get medical advice straight away.
If you have any questions or would like more information, speak to your GP.
While you’re exercising, pay close attention to how much effort you’re putting in. And as well as the exertion, think about the tiredness and physical stress you feel. Try not to focus too much on any one factor but instead, aim to concentrate on your total, inner feeling of exertion. Don’t under- or overestimate, just be as accurate as you can.
Exertion level Example of activity 6 7 Extremely light Tying your shoelaces 8 9 Very light Gentle walking 10 11 Light Faster walking, but there’s no change in your breathing 12 13 Slightly hard Brisk walking – your heart rate increases but you don’t feel out of breath 14 15 Hard Activity that gets your heart thumping and makes you breathe very fast 16 17 Very hard Activity that means you’re really tired and have to push yourself to continue 18 19 Extremely hard The most strenuous activity you’ve ever done – you can’t keep it up for long 20
- Start active, stay active: a report on physical activity from the four home countries’ Chief Medical Officers. Department of Health, 2011. www.gov.uk
- High-intensity interval training. American College of Sports Medicine. www.acsm.org, accessed 1 June 2015
- Weston M, Taylor KL, Batterham AM, et al. Effects of low-volume high-intensity interval training (HIT) on fitness in adults: a meta-analysis of controlled and non-controlled trials. Sports Med 2014; 44(7):1005–17. doi:10.1007/s40279-014-0180-z
- Ramos JS, Dalleck LC, Tjonna AE, et al. The impact of high-intensity interval training versus moderate-intensity continuous training on vascular function: a systematic review and meta-analysis. Sports Med. 2015 May; 45(5):679–92. doi:10.1007/s40279-015-0321-z
- Weston KS, Wisløff U, Coombes JS. High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: a systematic review and meta-analysis. Br J Sports Med 2013; 48(16):1227–34
- Boutcher, SH. High-intensity intermittent exercise and fat loss. J Obes 2011; 2011:868305. doi:10.1155/2011/868305
- Alahmadi MA. High-intensity interval training and obesity. J Nov Physiother 2014; 4(3): 211. doi:10.4172/2165-7025.1000211
- Sherwood, l. Human physiology: from cells to systems. 9th ed. Boston: Cengage Learning; 2015
- Bacon AP, Carter RE, Ogle EA, et al. VO2 max trainability and high intensity interval training in humans: a meta-analysis. PLoS One. 2013; 8(9):e73182. doi:10.1371/journal.pone.0073182
- Evans CH, White RD. Exercise testing for primary care and sports medicine physicians. New York: Springer; 2009
- The Borg Scale of Perceived Exertion. Harvard TH Chan. www.hsph.harvard.edu, accessed 17 September 2015
- Measuring physical activity intensity. Centers for Disease Control and Prevention. www.cdc.gov, published 11 August 2014
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