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 63.

    35. slouching_towards_Bethlehem
    I have always assumed, based upon received wisdom, that you don't get a proper aerobic effect until you have exercised strenuously for at least 35 minutes.
    After 35 minutes strenuous exercise you'll be getting an ANAEROBIC effect (thats why you get a stitch..lactic acid build up). As soon as you double your resting pulse rate exercising you're getting a benefit.

  • rate this

    Comment number 62.

    We don't see animals in the wild worrying about getting in large amounts of exercise or warming up before they do but they seem to ne leaner and fitter than us - apart from when we give themn human eating habits. So why shouldn't this work for a number of people.

  • rate this

    Comment number 61.

    I'm not an expert, so I can't say if it will make you fit or not. If it did though, we'd see alot of unemployed people in the fitness industry!

  • rate this

    Comment number 60.

    So your saying these 100m sprinters are unfit? Do you really think these 100m sprinters run 2-3 miles for their training.. no! They do interval training. HIT can actually help burn fat without using muscle.

    This article missed out a main point here and how it effects your nervous system - read up on this.

    Trust me you'll wish you did interval training if your child ever runs towards a busy road.

  • rate this

    Comment number 59.

    I'm loving all the comments from people reading what is basically a report of scientific studies, and declaring, based it would seem on prejudice rather than evidence "Naa, that doesn't work!"
    I find the idea surprising, but interesting. As I've not conducted any such study I have no choice but to accept the findings... and if I were to disagree I would be honour bound to investigate and show why!

  • rate this

    Comment number 58.

    What a complete load of rubbish. Shame on you BBC, giving this the time of day. If you want to be fit, it takes hard work, and time. There is no "easy way", and I do not need a "study" to work that out for myself.

  • rate this

    Comment number 57.

    Is it any wonder the British are so fat when they look to do the least exercise possible? Go to Europe the first thing you notice is how much better everyone looks. Here beer guts and flab hanging out is the norm.

  • rate this

    Comment number 56.

    It's funny how so many commenters are willing to overlook this study because it doesn't mesh with their idea that being fat and/or unfit is a moral failing and not largely genetically defined. You don't see these skeptics pouring out of the woodwork on the typical "being fat is extremely deadly!" and "everybody responds exactly the same to exercise" stories. Try thinking like a scientist, please.

  • rate this

    Comment number 55.

    22. Dominic
    Sounds like exercise for the lazy. I don't believe you can get a high level of fitness this way. Try doing a marathon with 3 minutes a week exercise. You'd collapse before you'd done 5 miles.
    I swim between 1.5-2kms after work 2 or 3 nights a week.... I couldn't run 5 miles! Marathon running requires seriously above normal fitness

  • rate this

    Comment number 54.

    Interval training has been around for a long time but is normally part of a much more stringent regime. I would question the benefit of doing such a tiny amount of activity on overall fitness. Also, I can think of other reasons for the trial to be less effective on some people - eg existing fitness levels. And how exactly does cycling work the upper body? Interesting but wld like to know more.

  • rate this

    Comment number 53.

    The biggest effect this study is going to have is to simply validate for the millions of couch potatoes that they are fat due to their "genes" rather than their lifestyle, so there's not much point in trying.

  • rate this

    Comment number 52.

    It is ill advised for people who do not regularly exercise to partake in vigourous exercise, even for a few minutes. You are likely to suffer injury, or a heart attack. Dumb advice indeed. Exercise gently and regularly, stretch every day, and after exercise (not before!). There is no short cut to fitness. And do something you enjoy, or you simply wont do it!!

  • rate this

    Comment number 51.

    Can no-one read here? It was 3 minutes high intensity and 9 minutes low intensity - not just 3 minutes on it's own.

    If you intersperse maximum exertion with lower exertion (but still exertion) then this is obviously better than doing jack.

    3 minutes maximum exertion is running 12-15 100m sprints, full-out. Do that and I'm quite sure many people will get fitter.

  • rate this

    Comment number 50.

    The best way to get fit for a marathon is to run marathons.
    The best way to get fit for a football match is to play football.
    The best way to get fit to climb a mountain is to climb mountains.
    And so on.
    HIT will train the body to so such work.

  • rate this

    Comment number 49.

    Interesting, I don't own a car so I do quite a bit of 'Power Walking' when I go to the local shops. I know I don't get enough exercise overall & could stand to lose a few pounds, so not sure if I have the magic genes.

    I don't know why there are links on BMI Index though, as it's highly inaccurate & been discredited for decades. Being very tall, my target weight would make me look very ill indeed

  • rate this

    Comment number 48.

    I am 60 this year. Last night I did a session of 'Spin Cycle' at the gym. For 45 minutes we were close to the brink of exhaustion sprinting and hill climbing. Less than one minute into cool-down I felt recovered. I can run up cliff way paths, run for a bus and play football with my younger children without feeling breathless.

    I do not believe I could've achieved this fitness with 3-minute bursts.

  • rate this

    Comment number 47.

    I remember studies from some time ago that recommended whatever exercise you do, finish it off with a few minutes intensive effort, this really heightens the effect, basically the heightened state lasts for hours, increasing fitness and calorie loss. Not sure why they are saying they dont know why it works, seems pretty basic common sense to me.

  • rate this

    Comment number 46.

    Interesting study, however I feel that exercise should be a major part of lifestyle, not something crammed into 5 minutes a week. A walk allows you to enjoy your environment, a badminton game is social, an hour at the gym is 'me time' away from the office and home, a swim is a perfect time for thinking and relaxing. In any event, look after your body, you only get one.

  • rate this

    Comment number 45.

    This is just a charter for the couch potato. They must all be reading this thinking how fit they can keep by sitting, waiting for their rear ends to grow whilst vigorously waving their arms and legs about for 3 minutes once a week thinking it makes them as fit and sprite. It doesn't. I can hear the lectures from the obese masses now... "Exercise is pointless. I read a study that said..." etc etc.

  • rate this

    Comment number 44.

    I do HIT but in relation weight training: 3 all out sets once a week including the big compounds (chins, deadlifts, dips, leg press). It takes around 5 minutes and I'm in great shape.


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