Shoes changed my life (and saved my knees).
When I was preparing for my first marathon years ago, I had invested so much time in training, coaching, supplements, strength-training, cross-training, etc. I felt prepared, but my legs were becoming so achy—especially my knees. The one thing I had not invested in was shoes. I always bought the mid-level price shoes, which seemingly felt good.
When I finally got to the point where I couldn’t surpass 6 miles without extremely achy knees, I had a video test of my running done. I found I had significant pronation, and the shoes I had been purchasing did not have ample support for my gait. I purchased shoes that were double the price of what I’d been purchasing, and within one week the pain subsided.
I still wear the same shoes today, and I am injury free with hundreds of miles logged.
If you cannot afford to go in on the most perfect shoe for you, I recommend finding the imbalances that a shoe can fix and speaking to a trainer who can give you strength training exercises to help balance out any imbalances you might have. This will not only help with running, but with everyday functionality.