Wednesday, May 19, 2010

How many minutes a day should you exercise?

I don't think there's a one size fits all answer.

Last week the Canadian Society for Exercise Physiology (CSEP) and ParticipACTION released their new recommendations that saw their minimum recommended amounts of exercise drop to 60 minutes a day for children and 90-150 minutes a week for adults.

I was critical of their press release. I felt that by providing specific numbers and omitting calls to action to change the environment it perpetuated the notion that sloth is a disease of the individual, and by extension for many, that so too is weight and that the solution is increased personal responsibility. To me it seemed akin to the NRDC and Greenpeace putting out a press release about cleaning up the oil in the gulf of Mexico without a call to action for oil rig regulation reform and a call to actually plug the leak.

A friend and colleague emailed me to tell me that they felt I had been too harsh and that my post misconstrued the press release because I focused on the fact that the minimums had dropped while ultimately the report strongly encourages people to do more than the minimums. They also felt that having evidence-based guidelines for exercise was a good thing and mentioned that they felt evidence-based guidelines were something I ought to support given my call for evidence to be applied to Canada's dietary guidelines.

That led to an interesting email exchange (we're still friends) and given they read into my post intentions that weren't there, I figure it's best to flesh them out here.

So let me start by saying that I do not believe that society has recently been afflicted with an epidemic of laziness. People haven't changed, the world has, and to steal a line from Dr. David Katz, it used to be that calories were scarce and physical activity was unavoidable while today physical activity is scarce and calories are unavoidable.

Consequently I feel that press releases that simply focus on how many minutes a day everyone supposedly ought to be exercising fail to address the root cause of exercise deficiencies - the world we live in.

Cheap cars, suburbia, non-walkable neighbourhoods, irrational fears of child abductions, always on electronic tethers to work, constant chauffeuring of kids to activities, the Internet, video game consoles, hundreds of television channels, big box malls, etc. If we want people to take responsibility for exercising, I think we need to ensure we do our very best to empower them to do so and that means changing the world.

Elementary school children aren't lazy, they're just faced with a different environment than we were when we were kids and consequently their weights have risen. While my take on the literature is that the rise is more due to intake increases rather than output decreases, when it comes to exercise people always tend to focus on the "when we were kids we used to play outside" argument. Yes we used to play outside, but the alternative then was staying home with our parents and playing with them, talking to them, or doing chores, whereas now more attractive alternatives abound. Kids, like adults, are consumers of both time and pleasure. If there's a behaviour that's more fun, they're likely to choose it and many find playing video games, surfing the net, instant messaging, and iPhones, to be more entertaining than a ride around the block, a game of cops and robbers or hopscotch in the driveway.

I also disagreed that a fair comparison can be drawn between the utility of evidence-based exercise recommendations and evidence-based dietary recommendations. I disagreed there because the simple fact of the matter is that more exercise is good, any exercise is good and all exercise is good. Whether it's formal gym based exercise, playing with your kids, gardening in your yard or shoveling snow in the winter, simply put, it all counts, it's all good for you and doing more is better. The same certainly can't be said for food and consequently having more specific guidelines with food is much more of a necessity.

My friend felt that my assertion that the personal responsibility focus should simply be on getting people to exercise more rather than providing them with a specific number to shoot for was flawed and perhaps overly simplistic.

My thinking's pretty straightforward. It stems from SMART goal setting, which suggests that while goals should certainly be specific, goals should also be both realistic and attainable. What's realistic and attainable for one person may not be for another and frankly telling sedentary children or adults that they need to at a minimum exercise for 60 minutes a day isn't likely either.

More importantly though, I wonder if we'd be better off simply encouraging people to exercise more because that's more likely to have an actual impact than specific minute based minimum targets.

People should be encouraged to find small bouts of lifestyle based or more formalized exercises, with the recommendation being that every 5-10 minutes count.

Certainly the literature would suggest that multiple short bouts of exercise have many of the same health benefits as you'd get from more discrete large bouts of exercise, but perhaps more importantly research might suggest that people encouraged to find short bouts of exercise in fact do more exercise overall than folks trying to find those big blocks of time.

One such study, conducted in 1995 by John Jakicic and colleagues found that women encouraged to find multiple 10 minute bouts of exercise, exercised more frequently and with greater total duration than women who were trying to carve out 40 minute blocks of time for exercise.

Undeniably more is better, but why paralyze people with huge chunks of minimum more?

One argument my friend made, and it's a theoretical one, does fairly refute my post from a few days ago. They wondered whether or not CSEP and ParticipACTION would have been permitted to make specific governmental calls to action in their press release. They wondered whether or not the involvement of the Public Health Agency of Canada would have precluded any criticism of governmental inaction. I don't know the answer to those questions and indeed it's possible that they were muzzled and while if true it might help to explain the omission, it doesn't help change my most basic concern.

Press releases are by their nature picked up by the press. The press by its nature is busy and with rare exceptions doesn’t spend tremendous amounts of time researching back stories to succinctly worded press releases. While ParticipACTION may be involved with the Active Health Kids Report Card that does indeed include governmental calls to action as part of its 80 pages of commentary, the average reporter isn't going to dig that up to include it in their coverage of this story.

Consequently absent the call to action to government in the press release on exercise, what the CSEP/ParticipACTION press release does, along with provide recommendations as to how many minimum minutes of exercise are necessary, is continue to perpetuate the myth, a dangerous one at that, that individuals themselves are the problem, and not their environment. And while I don't for a moment believe that CSEP or ParticipACTION set out purposely to do so, press releases and calls to action which embolden the flawed notions that inactivity and weight are diseases of the individual have the unintended consequence of hamstringing efforts for the dramatic environmental reforms we so desperately need by taking attention off of the cause and focusing it only on the consequences.

So my answer to the question of how many minutes a day should you exercise? As many minutes as you can enjoy, and every single one of them count.

Murphy, M., Blair, S., & Murtagh, E. (2009). Accumulated versus Continuous Exercise for Health Benefit Sports Medicine, 39 (1), 29-43 DOI: 10.2165/00007256-200939010-00003

Jakicic JM, Wing RR, Butler BA, & Robertson RJ (1995). Prescribing exercise in multiple short bouts versus one continuous bout: effects on adherence, cardiorespiratory fitness, and weight loss in overweight women. International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity, 19 (12), 893-901 PMID: 8963358