British Columbia

Pollution vs. exertion: what's the best speed to walk or cycle?

A UBC researcher says the benefits of a workout from riding a bike or walking on a roadway need to be balanced with the ambient pollution. He says it all comes down to breathing and speed.

Research suggests finding a 'sweet spot' between exerting yourself, not breathing too much pollution

A UBC researcher says cyclists and those walking for exercise need to find a speed "sweet spot" to get the most benefit from their workout. (Christer Waara/CBC)

There are a lot of things to keep in mind when cycling or walking down the street: rules of the road, other users and now breathing, according to a University of British Columbia study.

Assistant professor Alex Bigazzi says cyclists and walkers who want to get the optimal benefits of their exercise also need to control their breathing in a way that minimizes pollution from motor vehicles while at the same time exerting themselves enough for the exercise to have an impact. 

"When you're cycling faster or walking faster, you're exerting more energy and of course, you're going to be breathing harder and breathing at a higher rate," he told All Points West host Robyn Burns.

"But at the same time, you get there quicker and get out of the polluted roadway environment sooner."

Bigazzi developed a model to find the "sweet spot" in terms of travel speed, and says it generally falls between 13-15 km/h for cycling, and three to five km/h for walking, which is a moderate level of exercise intensity for most.

He says a good way to judge your intensity is the "talk test": if you can hold a conversation but don't have enough breath to sing, you're probably at a moderate level of intensity.

He also says in areas of low pollution, you can increase speed without worrying about inhaling more pollution.

The optimal speed varies based on age and gender, Bigazzi says, and his research, published in the International Journal of Sustainable Transportation, found the following "sweet spot" speeds:

With files from CBC Radio One's All Points West

To hear the full story, click the audio labelled: Pollution vs. exertion: what's the best speed to walk or cycle?