Can three minutes of exercise a week help make you fit?

Michael Mosley on exercise bike

A few relatively short bursts of intense exercise, amounting to only a few minutes a week, can deliver many of the health and fitness benefits of hours of conventional exercise, according to new research, says Dr Michael Mosley. But how much benefit you get from either may well depend on your genes.

When I first read studies which suggested that I could make significant and measurable changes to my fitness by doing just three minutes of exercise a week, I was incredulous.

But this apparently outrageous claim is supported by many years of research done in a number of different countries including the UK, so I decided to give it a go.

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Aerobic fitness is a measure of how good your heart and lungs are at getting oxygen into your body and is an excellent predictor of future health”

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My guide into the world of High Intensity Training (HIT), was Jamie Timmons, professor of ageing biology at Birmingham University.

Jamie assured me that by doing just three minutes of HIT a week for four weeks, I could expect to see significant changes in a number of important health indices.

The first, and the one I was most interested in, is insulin sensitivity. Insulin removes sugar from the blood, it controls fat and when it becomes ineffective you become diabetic.

My father was a diabetic and died from complications of that disease. Jamie assured me that research from a number of centres has shown that three minutes of HIT a week improves insulin sensitivity by an average of 24%.

The second improvement I was likely to see would be in my aerobic fitness. Aerobic fitness is a measure of how good your heart and lungs are at getting oxygen into your body and is an excellent predictor of future health. I asked Jamie why.

"The simple answer is we don't know," he replied. "What we do know is that it is a very, very powerful predictor of future health."

Genetic test

So if I could improve my insulin sensitivity and my aerobic fitness then that should improve my general health. But Jamie said there was a potential sting in the tail. There was a possibility that I wouldn't improve. Not because HIT doesn't work but because I've inherited the wrong genes.


Michael Mosley
  • Michael Mosley presents Horizon: The Truth About Exercise on BBC Two at 21:00 GMT on Tuesday 28 February 2012 or watch online via iplayer (UK only) afterwards at the above link

The fact is that people respond to exercise in very different ways. In one international study 1,000 people were asked to exercise four hours a week for 20 weeks. Their aerobic fitness was measured before and after starting this regime and the results were striking.

Although 15% of people made huge strides (so-called "super-responders"), 20% showed no real improvement at all ("non-responders").

There is no suggestion that the non-responders weren't exercising properly, it was simply that the exercise they were doing was not making them any aerobically fitter.

Jamie and his collaborators investigated the reasons for these variations and discovered that much of the difference could be traced to a small number of genes.

On the basis of this finding they have developed a genetic test to predict who is likely to be a responder, and who is not. Jamie offered me that test. But I would not be told the results until I had completed my HIT regime.

I agreed, had blood taken and went through some baseline tests to assess my starting point, fitness-wise. Then I began to do HIT.

Full throttle

It's actually very simple. You get on an exercise bike, warm up by doing gentle cycling for a couple of minutes, then go flat out for 20 seconds.

A couple of minutes to catch your breath, then another 20 seconds at full throttle. Another couple of minutes gentle cycling, then a final 20 seconds going hell for leather. And that's it.

Michael Mosley tries high intensity training

So how does it work? According to Jamie, and other researchers I spoke to, part of the explanation is (probably) that HIT uses far more of our muscle tissue than classic aerobic exercise.

When you do HIT, you are using not just the leg muscles, but also the upper body including arms and shoulders, so that 80% of the body's muscle cells are activated, compared to 20-40% for walking or moderate intensity jogging or cycling.

Active exercise also seems to be needed to break down the body's stores of glucose, deposited in your muscles as a substance called glycogen. Smash up these glycogen stores and you create room for more glucose to be sucked out of the blood and stored.

Somewhat sceptical I went off and dutifully did my four weeks of HIT, making a grand total of 12 minutes of intense exercise and 36 minutes of gentle pedalling. I then went back to the lab to be retested.


The results were mixed. My insulin sensitivity had improved by a remarkable 24%, which was extremely satisfying, but my aerobic fitness had not improved at all.

I was crestfallen, but Jamie was not surprised. It turns out that the genetic test they had done on me had suggested I was a non-responder and however much exercise I had done, and of whatever form, my aerobic fitness would not have improved. My dreams of winning Olympic gold ended there and then.

I will continue doing HIT because I can see the benefits. It won't suit everyone, because although it is short, it is extremely intense. Like any new exercise regime if you have a pre-existing medical condition you should consult your doctor before trying it.

Michael Mosley presents Horizon: The Truth About Exercise is on BBC Two at 21:00 GMT on Tuesday 28 February 2012 or watch online afterwards at the above link.


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  • rate this

    Comment number 323.

    Mrs Odicean and I used to exercise vigorously for 3 minutes about once a fortnight but gave it up many years ago when I got knee trouble.

  • rate this

    Comment number 322.

    I guess people do what works, what they enjoy and what fits into their schedule. I like to cycle, and am fortunate enough to be able to take off for hours at a time to just chew up the miles. I'm still carrying 30-odd pounds that I'd like to see disappear but my fitness levels are better than they have been in my life.

  • rate this

    Comment number 321.

    Exercise? I wish it were that easy to get motivated; it must be for some, I guess, but not for me sad to say!

  • rate this

    Comment number 320.

    This study shows that there may be an improvement compared to a sedentary individual and is concerned primarily with metabolism. However we shouldnt forget that this cannot possibly improve aerobic fitness as there is no aerobic activity, and as a result this type of exercise is unlikely to improve issues of body fat or cardiovascular fitness. Obviously depends on how you define 'Fit'!

  • rate this

    Comment number 319.

    I've been doing HIT for a couple of months now, in addition to exercise at least 3 times a week with a careful tracked diet. However I'm not losing any weight so after watching the program tonight I have come to the conclusion I am in the non responder group of people. So the BIG question is this, How does a non-responder lose weight?

  • rate this

    Comment number 318.

    Fascinating programme ended by the comment "The seat is the killer". I wonder how we have arrived at this convention of sitting all day long rather than standing for periods. After 20 years in IT I think I'm the only person I know who types standing up. I use a mini-stepper with a laptop stand and despite initial raised eyebrows people are now fine with it. 200 cals per hour against 60 sitting

  • rate this

    Comment number 317.

    Any exercise is better than none, but what people really need is sufficient recreational time to do proper exercise and proper sports.

  • rate this

    Comment number 316.

    That explains it! Thirty years ago training as a cox with OUBC I tried to do interval training scientifically measuring heart rate and recovery times etc. After four weeks there was no identifiable improvement in my stamina as every book then available predicted! Now I can say that I am a non-responder.

  • rate this

    Comment number 315.


    I was trully amezed by the outcome of search what best way of exercise. Mainly the last 2 way of exercise is great. I think I'm going start one of them. Maybe I'll ask my physiotherapist for this type training. However I'm glad that I saw this program in lazy chear somewhere in the Netherlands.

    With kind regards,


  • rate this

    Comment number 314.

    As an instructor of the 'Spinning' indoor cycling programme for the past two years and having a student rider for the past 15 years, I am personal proof this method of training is effective. In a group class envirionment we perform seated hill sprints to this 'specification' as part as interval training to simulate hairpin bends on hills as part of a 45 minute ride. Get 'on yer bike'!

  • rate this

    Comment number 313.

    I bought a wind-up watch.

  • rate this

    Comment number 312.

    I exercise for 1 second 3 times a week. I lost 15 stone. Blah blah blah.

    If you really want to feel fitter and increase your well being you must exercise for longer. About 30-40 mins 3 times per week. On the same page you can see that the so-called experts have been wrong about hip implants.

  • rate this

    Comment number 311.

    *Almost* any exercise is better than none, but high intensity exercise has significant injury risks if taken by itself. Always warm up first, and don't apply high intensity to weight training unless you exercise regularly to work up to it. If you want to loose weight cut out processed foods or simply tell your family you don't care about how you look and how soon it will kill you.

  • rate this

    Comment number 310.

    Well, some were poo poohing this, but after watching the programme - there may be something in it. I understand that to build muscle you need to life some very heavy weights for few repetitions until failure. The damage that you cause then persuades the body to repair the tissue and to increase the size of the muscle - so it is the intensity of the exercise that is the key - not the duration.

  • rate this

    Comment number 309.

    The government, medical & teaching professions really must improve their general messages on exercise. People who cant improve their aerobic capacity no matter what yet who try really hard, are exercising anaerobically. This means struggling to exercise at heart rates so far beyond safe limits that long term harm arises. No one warned me of the risks I faced yet all knew how hard I worked.

  • Comment number 308.

    This comment was removed because the moderators found it broke the house rules. Explain.

  • rate this

    Comment number 307.

    Every morning I do ten push ups, stop and then do the same with the right eyelid. Smashing!

  • rate this

    Comment number 306.

    Just watching this on TV now.

    Don't believe for one second that exercise without warm up could be more beneficial than with . . or simply incorporating it into your daily lifestyle.

    Or that genes can determine that some people do not benefit from exercise at all . . nonsense.

    It's physics not biology ! Exercise requires energy expenditure.

    Expend energy and eat less and you will benefit.

  • rate this

    Comment number 305.

    When Michael Mosley failed to get the results claimed he was told this was because he was a “non-responder”. Sorry, but if experiments were carried out testing telepathy & whenever a subject failed to achieve the results claimed they were simply told this was because they were a “non-responder” or “inherited the wrong genes” the experiment would be ridiculed & dismissed out of hand.

  • rate this

    Comment number 304.

    The writer has little understanding of all types of diabetes. The statement "when it becomes ineffective you become diabetic," does not relate at all to type 1, which is an autoimmune disease. The article further implies that this will somehow magically improve or prevent you getting diabetes, which is often genetic for type 2 and totally inaccurate for type 1. Further education is needed here!


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