The first of these was a question about how to know when a running shoe needs replaced. Here is my answer:
Question: What are the best indicators it may be time to buy new shoes? I did a 5k today and the first time I tried running my knees hurt terribly. When I was jogging last summer no knee pain. So I am wondering if it may be related to needing new shoes.
Answer: This is an excellent question. It is possible that it could be time to by new shoes. There are several indicators that your shoes could be worn, and having little aches and pains on an easy run (when there is no other apparent cause), could be one of them. For people who are in tune with their bodies, this is often the first sign.
There are some other ways that you can get a clue. One is to actually look at your shoes. This may sound funny, but most of us don’t really look at our shoes. No, it is not just because we are out for the early morning run before our eyes are all the way open. It is because putting on our shoes is so automatic that we often don’t see them.
Take a look at your shoes. Ignore for now how dirty and sweaty the upper is. Instead, turn them over and look for wear on the sole. Are the heels or midfoot worn down. For me, I strike on the outside of my foot, and if I turn a shoe over, I can often see clearly that the edge of the shoe is almost gone. Oops!!
Because of where my wear is, I often start turning my ankle because the shoe is so worn, I am falling off of the outside. On the other hand, if your shoes are worn down on the inside, you could be putting more torque on your knees and hips. Also, look at the shoe from the rear. Is it listing off to one side, like the upper is sliding off the midsole? If so, it is probably time to replace the shoe as well, for the aforementioned reason of putting strange torque on the knees and hips.
Another area of the shoe that can break down is the midsole. That is the area between the bottom of the shoe and the part where your foot sits. Over time the cushioning there can become compressed and stop giving you the cushioning you need. Midsoles generally are made from some type of foam material and can wear out from being used for miles and miles, but they can also wear from being wet (why you aren’t supposed to wash running shoes). Sun and heat can also break down the foam. If you have been drying your shoes with heat this winter, that could affect things.
The test for this type of wear is to look at the side of the shoe to see if there are lots of lines and wrinkles. If there are, that means the midsole is wearing down. A second test is to push your thumb into the midsole at the middle. Does it bounce back well, or does it stay pretty flat? If it doesn’t seem to rebound, the midsole may be worn out, even if the rest of the shoe is not showing a lot of wear.
However, the best way to know when to replace running shoes is to keep a log of the mileage you have on them. This is an absolute must!! If you only have one pair of shoes, this is fairly easy. Just write down the day you got them, and then add up your weekly mileage since then. (What???? You aren’t keeping a mileage log??!! Start right now!). The advice on when to replace shoes varies from 300-600 miles from most sources.
This is a pretty personal thing and also varies by shoes. I find that I start to notice the lack of cushioning (by feel) on my shoes at about 350. I replace on the low end, but I do have one shoe model that I can get many more miles on. I have several pairs of this one shoe, and I am over 500 on two of them and still wear them without a problem (I just don’t use them for my long runs). On the other end of things is a shoe like the Kinvara, that I dearly love but which I have to replace usually around 300 because of outsole wear (annoying!!!).
Once you start keeping a log, you will start to get a sense of how long shoes last for you. Then when you start getting that achy feeling, you can check the numbers and decide if the shoe is done or whether it is just one of those days.
A final recommendation to prolong shoe life and to avoid injury is to have more than one pair of shoes and rotate them. The foam in the midsole needs some time to refresh itself, and running in the shoes every day does not give the shoes time to refresh as well. Having two pairs helps with this process. Also, if you have two different models of shoes, you get a slightly different foot strike in each, which helps avoid repetitive motion injuries, especially for marathoners. Of course, keeping the mileage log gets a little trickier here.