Lab Rat

Adding to the Rotation

We’ve all heard it. You need to change your shoes after about 500k. But do you? What about simply rotating your shoes or varying the surface you run on? Is this something runners should consider?

“People give these numbers for when you should replace your shoes, but there’s generally no consideration of the runner’s body mass and shoe wear, so the number is often arbitrary,” says biomechanist Dr. Max Paquette, from the University of Memphis.

A former collegiate athlete in cross-country and track at the University of Guelph, Paquette is a strong believer in shoe rotation to prevent injury. “Running injuries a re related to the amount of muscle and skeletal tissue loading. These tissues get overloaded in some way, they are not given enough recovery time and get damaged.”

Although the science behind shoe rotation is lacking, Paquette points to one study that was done by a group of scientists in Luxembourg and published in t he Scandinavian Journal of Medicine& Science in Sports. It s aim was to determine if runners who used different pairs of running shoes are at a different risk of running-related injuries. It turns out runners who got injured more often used one pair of shoes during training while those who used at least two pairs tended to get hurt less.

The study goes on to say, “the concomitant use of different pairs of running shoes will provide alternation in the running pattern and vary external and active forces on the lower legs during running activity. Whether the reduced injury risk can be ascribed to alternation of different shoe characteristics, such as midsole densities, structures or geometries cannot be determined from these results and warrants future research.”

Although some of us may think buying more shoes is a ploy from running shoe manufacturers and specialty running shoe stores, this is not so, says David Korell, footwear merchandiser for New Balance Canada.

“We typically say that rotating two pairs of shoes every other day with different offsets within the same genre can help strengthen and adapt lower limbs in different ways,” says Korell. “A person may wear one shoe with a thicker stack height and a certain drop and a second shoe with less stack height and a different drop, both from within the same category. That would be the healthy approach and may just help contribute to runners staying injury-free.”

Paquette agrees that the more variable the movement, the more you’re able to change where the forces are acting on the tissues of the body. If you run in a high heel drop shoe versus a low heel drop shoe, every time the foot strikes the ground, the foot is going to be in a slightly different position. By changing the position of the body, you’re effectively changing how forces are being applied. Just making small changes may be enough to allow certain tissues to recover by running in a different shoe.

“I do believe changing things up, whether it’s footwear or something else like the terrain you’re running on, is important. When I ran at Guelph, I often rotated up to five different shoes: stability, a few pairs of neutrals and a few racing shoes that I would only run in occasionally.”

The only equipment a runner has is his or her running shoes. “Runners need to mix it up and not just their shoes,” says Janette Yee, athletic therapist at the Toronto Athletic Club. Although rotating your shoes is a good idea, it’s not the only option. “Runners should also try running on different terrain and surfaces. This way your body doesn’t get used to the exact same demand.” Biomechanist Dr. Geoff rey Gray, founder and president of Heeluxe in California, agrees. “It requires your body to explore movement patterns and use them a little bit differently; I also feel it’s good to run at different speeds. Changing your shoes does create different sensory-stimulus, which helps our body to tune itself to be a better runner.” As far as Paquette is concerned, the idea that runners need to change after X amount of kilometres because your shoe is getting tired and old tells us the whole shoe industry has made us weak. Perhaps the shoe isn’t the whole problem. “Perhaps our feet are weak and lazy and they’re unable to move in their naturally protective way and now we are more susceptible to injury. In my shoe rotation I’ve included a low heel drop shoe to provide my feet with a type of ‘workout’ if you will. I only complete short runs in those, but I do try to include a less supportive shoe in my rotation for that reason.”

Perhaps changing the stresses on your body – whether it’s rotating your shoes, running on different surfaces or even taking some time off – is worth exploring. As for changing your shoes after a certain number of kilometres? Dr. Benno M. Nigg, professor emeritus of biomechanics at the University of Calgary, says only you and your body can really tell if you need to switch out your shoes. “Change them when they’re not comfortable,” says Nigg. “That’s my recommendation.”