Commuter cycling: does it help your health?

In an earlier post I explained that recently I have been making more individual cycling trips than at any point in the last thirty-odd years. I also commented, when comparing the subjective experiences of cycling and walking, that cycling offers a wider range of physical intensity.

Even though most of my recent cycle trips have been short distances ( < 5 miles) it has been very striking that even a short, slow, flat, offroad journey will involve bursts of energy that you simply do not get in a walking trip. This is partly because nowhere, nowhere is completely flat. But you don’t really remember it. Thirty yards up a bit of slope, enough to make you pant for a few seconds? Forgotten as soon as its over. Accelerating to get past a bus? You do it without thinking or bothering. And these events occur even in the trips of the gentlest, the slowest, the most pootlesome of bike riders.

This struck me as something where – viewed purely as everyday transport – cycling really does win over walking. Raising physical intensity in a walking trip is difficult. With effort, you can just about make walking as hard as a rather gentle bike ride. I had lately taken to breaking into a minimalist jog for parts of walking journeys and of course Bristol is famously hilly – but I’m both temperamentally impatient and interested in experimenting with this kind of thing and I have to admit that truly vigorous utility walking is never going to be that popular.

So I was very pleased to see my speculation confirmed at Commuter cycling: does it help your health? a talk by Professor Ashley Cooper [note, I’ll change the link to the actual powerpoints, once they’re up on the Bristol Uni website]. The talk was one of the events of the Bristol Cycle Festival

There is now a ton of evidence about the benefits of what has been given the jargon term “moderate to vigorous physical activity” and Prof Cooper sketched out some of the seminal studies (the London bus crews for instance – conductors and drivers provided a really neat pair of otherwise similar groups which differ consistently in their workplace levels of physical activity). However he went on to say that there is “little hard evidence” of the specific benefits of cycling – but there is some. (By “hard” he meant well-designed academic studies – there is of course masses of personal experience – anecdotal evidence is not necessarily trivial in the sense that it can point at a real phenomenon, but the proper studies do have to be done to test our intuitions).

Sorry, I’m digressing – I made fairly extensive notes and I don’t wish to just transcribe them. To get back to the point I started with, Professor Cooper said plainly that the available evidence shows that:

“cycling gives you a bigger bang for your buck in terms of health benefits [than walking]”

And that benefit is thought to be because of the higher overall intensity of cycling:

“it is intensity which gives you the health benefits”

The research into physical activity has always shown that intensity is important. “Intensity” (how much it raises your heart rate) is to be counterpoised to “duration” and the current thinking is moving towards saying that “high intensity + short duration” is better than “low intensity + long duration”. I see that my notes contain the line “for increases in life expectancy – duration does not matter”.

Not sure how accurate that note is – it does sound pretty radical. It’s interesting to me how knowledge about exercise and health has changed over the years. At one point it seemed to be thought that beneficial exercise had to be both quite intense and of fairly lengthy duration. Decades ago I recall being told that going for a five- or ten-minute run couldn’t possibly do me any good at all – and as for walking hah! Well I’ve gradually watched the advice change and now it seems that almost any exercise at all will do you some good. This is great news. (And, incidentally, a nice example of the way the way that science changes its picture of the world as more evidence comes in). Any exercise will do you some good, but (in a broad way) greater intensity gives better results.

A complication

My earlier post on the epidemic of sloth was just a little disingenuous because I omitted an important caveat. The report I referred to was clear that physical activity wasn’t quite the whole story. The other half of the picture is the amount of sedentary time – if moving is a plus then sitting is a minus. You could take a good dose of exercise and then wipe out the benefit by sitting at a desk for the rest of the day. This was completely new to me; Prof Cooper said that it is new to everyone because the conclusions are recent.

The importance of decreasing the amount of time you spend sitting inertly on your bum is yet another plus for cycling – a “double hit” in Prof Cooper’s words – because the time on the bike is time spent not lazing about. You might be sitting on a saddle but you are active. It’s an even bigger plus for walking because walking journeys take so long (I’m currently at the stage where I arrive half an hour early for everything because I’m still applying walking calculations and can’t quite believe how much faster the bike is).

This caveat about taking care not to sit around for most of the day is important. The finding that, on the whole, intensity is more important than duration can be easily misrepresented. The BBC Horizon documentary the truth about exercise (the full versions on youtube have unfortunately been taken down) did not exactly misrepresent things and it did spend plenty of time discussing the importance of non-sedentariness but the documentary gave a misleading overall impression. Nevertheless it was good enough to be worth looking out for repeats, if you haven’t already seen it.

The structure of the documentary resulted in a foregrounding of some research findings about capsule exercise. The findings are that it is possible to get the full benefits of exercise from a very small amount of maximum intensity exercise. In the documentary we see the presenter (the very affable, and medically trained, Michael Mosley) following a programme where he does three twenty-second intervals on an exercise bike. The idea is that you really have to go absolutely flat out – you need to be gasping and groaning at the end – but you only need do this minute’s-worth three times a week. This is quite staggering I’d agree. Unfortunately the documentary did not make it clear enough that this needs to be done in conjunction with reducing the amount of the sitting down. The programme was not structured in such a way that the central argument about exercise came through. Although all the pieces were in place it succumbed to the gosh-wow factor (perhaps from a sad lack of confidence in the mental acuity of its audience?) and this resulted in a degree of confusion. (Horizon seems to do this rather a lot).

Incidentally Prof Cooper remarked that when he presents to audiences of fellow academics and practitioners in the area of physical activity, there are always a bunch of people at the back who have deliberately chosen to stand rather than sit. That seems perhaps a little ostentatious to me, but in case you’re wondering, I’m writing this post standing at my desk, with the laptop perched on a bunch of boxfiles and I’ve been doing part of my desk work this way for a few months now.

Finally

This all seems plain enough to me. If you get to work on a bike you get some reasonably intense exercise every week day. Furthermore, the time it takes to get to work is not time spent immobile in a chair. Double hit.

This knowledge is not a big secret. “The government has been told about this. It does know … it’s up to them to do something about it” said Prof Cooper. We’ve been so battered by half-baked US rhetoric about “big government” that perhaps it needs spelling out: the government spends my taxes to do things that I cannot do on my own by means of my own individual choices. I damn well want my taxes to purchase public health by means of doing what is necessary to foster walking and cycling. Increased public health means an increase in the amount of choice you have in your individual pursuit of satisfaction. It leads to more freedom.

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