You may not always be able to tell whether you need a certain kind of shoe for a certain kind of exercise, but your body might be giving you a few clues. If your feet feel fine, but you are experiencing some generalized soreness in places like your knees and lower back, a not-so-obvious reason might be your shoes. As a hiker, I have definitely discovered the importance of having a good hiking shoe, especially after trying to scramble over a trail in cross-trainers, which don't offer the necessary ankle support for a mountain or two. When I took up squash, I also learned the value of a shoe that offers good lateral movement, at the cost of a slightly wrenched knee while wearing running shoes.
I was curious about the importance of owning different shoes for things like aerobics, cross-training, and strength training, so I hit the Internet in search of an answer. Podiatrists and chiropractors can trace a lot of foot and back problems to the right kinds of shoes. If you're a serious runner, then running shoes are the way to go. Even if you are a race-walker or walk long distances, running shoes are probably a better investment than walking shoes, since they have more toe room. If you're not a serious runner, though, for most kinds of gym exercise such as aerobics, weight training, and some racquet sports, cross trainers are the most versatile option. If you are a serious basketball or tennis player, having specialized shoes will also help you avoid common injuries due to lack of traction, support, and cushioning.