Might active travel decrease obesity?

For reasons explained previously, I’m not really that keen on the whole blogging thing. Apart from anything else, almost everything one wants to say will eventually be said by someone else, so what’s the point?

Here is today’s example, it’s from Joe Dunckley, and concerns the connection between lack of physical actrivity and the “obesity crisis”. It’s from what, he warns us, is a rather sciencey and not terribly finished piece – and yes, it is slightly confusing to read unless you’ve already read a bit about the debate he references. Nonetheless it contains a point with which I am in total agreement. Joe’s post is aligned with a central thrust of psychobikeology: stop thinking about individuals (oh it’s so terrible the way people behave! Let’s talk to them about it!), start thinking about systems (people behave the way they do for complicated reasons, most of which are related to external circumstances. How might we change those circumstances?).

(The full post is here)

“[Garry Taubes commenting on the obesity crisis, in the journal Nature] is right to treat those who “blame individuals for not following [healthy eating] advice properly” with contempt. But not because the advice is wrong. Because any “advice” — right or wrong — is going to be useless. This is not a problem that individuals have created for themselves, and it’s not a problem that individuals can be “advised” to solve for themselves. This is a problem of the environment that we live in: the types of food that are available to us, and the opportunities for an active healthy lifestyle that have been taken away from us. […]

“[…] obesity, is a process of physiology. But it’s a problem of environment. […] you can’t solve a problem environment with advice alone. Bad lifestyle choices are not an individual failing. Good lifestyle choices need an infrastructure to support them.”

Just to expand a little here, strategically, I think it’s best to avoid claiming “answer to the obesity crisis” as one of the benefits of a public policy which takes walking and cycling seriously enough to do what is necessary (just as I think it’s strategically best to avoid banging on about carbon emissions too much). This is because it is a huge oversimplification – and therefore becomes a source of yet more contrarian ‘debate’ and dithering. I think it’s better to point out how great physical activity is in health terms (and how effortless it feels when that activity just happens as part of everyday getting around) and skirt around the whole psychological rabbit-hole of dieting-and-weight-loss.

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.


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.

Epidemic of sloth

I have mentioned previously that I reckon one of the most serious of the negative effects of motorized traffic is car-induced sloth.

There is a ton of evidence that physical activity is almost incredibly beneficial to health – if it were a drug you could swallow they would have put it in the water supply by now. “A ton of evidence”. Hmmm yes, that is a bit handwavy, I know. So, for my imaginary reader who is a naïf in the shouty world of transport policy:

* A bibliography of some actual proper journal papers

*A more lengthy (and chatty) compendium of evidence from Cycling England (and the very fact that the government created a quango to promote cycling tells you something about the amount of evidence)

If you care to google some suitable terms, you will find that there is more.


So yes, ok fine. Personally I’m prepared to take as given that moving about under my own muscle-power is good for me. I don’t have to chase up every single journal article – I’ll trust the published work of epidemiologists and medical statisticians and physiologists and whoever because I have no reason whatever to doubt that their knowledge is much more deeply grounded than mine in their areas of expertise. So physical activity is good for you, and it is very “dose responsive” – even a small amount is beneficial and you have to do a huge amount for it to be damaging.

I was thinking about this yesterday, while walking back home from Bristol City Museum, where I’d gone to buy a nice card for my mum in the museum shop (about half an hour each way). I wondered about the other side of the problem – how much physical activity are “we” actually doing?

I knew the recommended minimum levels – a total of two and a half hours a week of brisk walking or normal cycling plus a bit of muscle-type exercise. Two and a half hours walking? That’s really not a lot. A fifteen-minute-each-way commute to work would cover it – then dig the garden at the weekend and you could be smug. And anyway, the world seems to be chock-full of amateur athletes these days. Whole magazines devoted to triathlon and running and cycling and climbing and anything you can think of. Whole shops full of (frankly, rather sexy, cough) sports gear. Endless, endless, internet chat about the arcana of sports footwear. Everyone’s at it! I was suddenly overcome with doubt – surely there just couldn’t be a problem with levels of physical activity? Find some research.

First stop for this kind of question has to be the Office of National Statistics. From there I found the publication statistics on obesity, physical activity and diet 2013. The physical activity section relied heavily on some research from 2008, the health survey for England – 2008: physical activity and fitness.

Part of the survey involved a people wearing accelerometers while going about their daily lives so we have some objective measure of activity levels. The standout sentence in the summary report was:

Based on accelerometry, only 6%of men and 4%of women met the government’s current recommendations for physical activity, by achieving at least 30 minutes of moderate or vigorous activity on at least five days in the week of accelerometer wear, accumulated in bouts of at least 10 minutes

5% of the population manage to do what is, or should be, for an average person (and I’m sorry to have to put it this way, but really) the equivalent of a piddly bit of walking. It even counted if you did it in 10 minute bursts – the time it took me to walk to the bus or tube when I lived in London, the time it takes me to walk to the coach station in Bristol.

But wait, you think, maybe the survey included a disproportionate number of “old folk”. Well it was a proper large random sample, so the proportions would have matched those in the wider population, but just before I disappear in puff of flabbergastedness, let me add that, of course, as you would expect, the youngest age group did take a lot more exercise:

Men and women aged 16-34 were most likely to have met the recommendations (11% and 8%respectively),

I hardly know what to say. Yes, I knew that levels of activity were not as good as they should be, but it really hadn’t connected for me quite how bad things are … and yet there’s all that hoo-har about sport and fitness and going to the gym and doing marathons for charity … oh, we are such symbolic creatures aren’t we?

The problem

Previously on Psychobikeology: As a child I resented being carted around in a car all the time, as an adult I loved to get about by walking and cycling and now I’m miffed that cycling is unpleasant because of all the cars.

Whatever. Wouldn’t the easiest solution be to adjust my attitude a bit?

No. The problem is not personal. The transport situation in the UK today – the amount of motor traffic which is tolerated – even thought of as ‘good’ – is damaging. The problem is too much motor traffic and the problem affects everyone, including the folks who love their dear little cars.

Why is there “too much traffic” rather than “not enough roads”? Why are there “too many private cars” rather than “too many petrol engines – we’ll be ok when we’ve finessed electric vehicles and algal biodiesel”? Why is it ‘damaging’?

Here’s the list (linked to the corresponding entries in the dictionary. internal links don’t work in some versions of IE):

Land take
Resource depletion
Social atomisation

Oh and carbon dioxide emissions of course – but I’ve left that off the list (even though it is important) because it is something of a diversion at this point. You will notice that even a non-polluting engine would only take out a few items from the above list.

The other big item is the opportunity cost – too much driving crowds out cycling and walking, preventing a public good.

I’d say that the biggest immediate good of cycling and walking is the health benefit. Just look up ‘health benefits of exercise’. Walking and cycling knock ‘going to the gym’ into a cocked hat because they require less willpower. and they make you feel good.

Bristol (introduction #5)

At the end of 2006 I moved from London to Bristol. Bristol is a very walkable city, but that didn’t do me any good, because in 2007 my legs started to seize up.

That’s sounds overdramatic, though it is actually what happened: I couldn’t stand on tiptoe, I couldn’t kneel down, I had to think very carefully before crouching. Attempts to jog resulted in something sharp and stabbing happening in my ankle, my knees were starting to grumble alarmingly, a sort of ‘clunk’ had appeared in one of my hips and for the first time in my life I experienced an ache in my lower back. Most of all, my feet hurt all the time. They ached from heel to ball and I couldn’t flex my arches. I’d go to bed with my feet hurting and I’d wake up with them hurting. I had experienced this latter symptom before and I’d solved it by walking barefoot as much as possible, but this no longer worked. Not only did my feet hurt in an achy, draining sort of way there was actual pain-type pain. Genuine fiery pain in my big toe joints. At its worst it was never quite bad enough to keep me awake at night, but it was bad enough that I thought that it might do so.

Without walking I felt bereft. It hadn’t occurred to me that exercise mattered to me – to say so seemed unbelievably pretentious, I mean, it’s not as if I went in for serious sport, that it was any part of my identity or anything. I’ve never done a long-distance footpath (there’s still time). I’m not one of those people who says “oh I just hate to be in an office all day”. I mean, here I am right now, voluntarily sitting at a computer. Yet it turns out that physical activity does matter to me – and it has to be outdoors. Gyms (and I have used them in the past) are good for specific purposes but a treadmill does not give me joy. What I left out of my earlier account of cycling in the London in the early eighties was that it coincided with coming out of a period of depression. Exercise has many physical benefits, but I need it for mental health. I curdle if I don’t keep moving and I need to feel the rain and the wind.

So I saw an excellent physio at the University of Bristol sports centre, who told me that my muscles were incredibly stiff, ‘sports-massage’d’ my legs (you really know when you’ve had this done) and gave me a load of stretching and balance exercises, which I still do because they help. I am now returned to my former bendiness – more or less – with no disturbing clunks or muttering knees. The pain in my toes has calmed down to a perfectly bearable stiffness. The physio also referred me to a podiatrist on the suspicion that I had something called “wear and tear damage” in my feet. The pod grinned enormously while bending my toes and said “Oooh yes, definite arthritic changes there”, but the verdict is actually not that bad. Things will only get worse slowly, and my woes are quite mild, really. Yes, they are, and I’m very grateful.

Yawn. Nothing more boring than someone else talking about their health.

But this is relevant because the bottom line remains that yomping aorund nice muddy hills is one thing but I just can’t pound the urban pavement in the manner or to the extent that I used to. Really, I have to exchange some of my walking for cycling.

Why is that hard? I used to love cycling around London. What exactly is the problem and what can be done about it?