Our choices regarding shoe wear are so important and often overlooked. Changing your shoes, whether wearing a different kind or purchasing a new pair, can often reverse pain and injuries in your back, hips, knees, or feet/ankles. Many people are simply wearing the wrong shoe, wearing shoes that should have been retired years ago, or both. For example, if you have pain with walking, consider what shoes you are walking in. Perhaps you are walking long distances with flip flops and no heel or arch support. Maybe you have been wearing the same shoes for the past few years and the soles are completely worn. Perhaps you have brand new sneakers with fancy orthotics causing too much rigidity in your shoe. In any case, a change in footwear can prevent or get rid of unnecessary discomfort.
There are so many choices and options for shoes. First we have to decide if we want sneakers, flip flops, clogs, hiking boots, winter boots, rain boots, ballet flats, high heels, etc. Then we have to decide what brand - Nike, Adidas, Asics, Saucony, New Balance, Brooks, Hoka One One, Mizuno, Sketchers, Under Armour, ... and that's just a few of the choices for running shoes. It can be overwhelming. Some of us have our go-to's, but those are regularly being updated with new additions. For example, my favorite running shoe is the Asics GT 2000. These shoes are now on their 5th edition, and I have had multiples colors in each version. Shoe companies make little tweaks with each update, so it is advised you buy as many as you can in the current edition if you find a pair you really like.
To pick a shoe, I highly recommend going to a shoe store and just trying a bunch on. Your body will tell you what feels best, and someone at the store should be able to help you out. I would go to your local running store where you can trial shoes on a treadmill or do a few laps around the parking lot to get a good feel before buying your favorite.
To determine when you need to retire your shoes, you can get an idea by looking at the wear patterns on them. The general standard is to replace your shoes every 400-500 miles if you are a runner. This is based on body size, the surface you run on, and how you run. I usually go on the lower side because my old running shoes become my "junk" shoes, so I continue to wear them around the house and in the yard for chores. You don't want to retire your running shoes after 600 miles and then continue wearing them all the time! That will set you up for aches and pains.
Pictured below are my new and old running shoes. The shoes on the right have been worn approximately 400 miles. Besides the dirt, can you pick out where the shoe is worn?
Below you can see how the middle of the forefoot and the heel is quite worn.
Here is a view from the back to show more of the heel wear. You can really see on the bottom where there is a loss of material. Without this material, the shoe is less stable and allows my foot to roll increasing my injury risk.
I am a heel striker, so the heel wears more than the forefoot. Below is a picture of a shoe from someone who runs more on the balls of their feet. You can see the increased wear in the front of the shoe where the toes strike the ground first instead of the heel.
Another area to check is the cushioning around the heel. The picture below shows how the gel under the heel has compressed and changed with more miles.
Finally, here is a pair of my rain boots that I have had for many years. You can see they are getting ready for replacement as evident by the wear in the heel. Just like a tire, you don't want to flatten the tread. I have no idea how many miles I have gone in these rain boots, but the wear pattern lets me know they're nearing the end.