First of all, one shoe is not made for every athletic activity. You must consider the type of activity in which you will be participating. Sport specific shoes help prevent injuries by giving support in the appropriate areas. A running shoe can create injuries if used for tennis or basketball. Running and walking shoes are made for straight-forward activities. Tennis and other court-shoes provide additional support for side-to-side motion. Purchasing shoes for each sport is important for preventing athletic injuries. Finding a shoe to complement your activity will help improve your performance and decrease your chance of getting injured.
What features do you need in a shoe? Three things should be checked in all shoes before they are tried on: heel counter, torsional stability, and "shoe break." The heel counter is the portion of the shoe surrounding the heel and should be firm and reinforced for extra stability. Torsional stability (the amount of twist in a shoe) is determined by grabbing the back and front of the shoe and attempting to twist as if one was wringing out a towel. Very little twisting motion should occur. The final feature to establish is where does the shoe "break" or fold. Attempts to fold the shoe in half should allow folding out near the toes at the most distant quarter of the shoe. Shoes that fold in the middle or near the heel may cause discomfort or even an injury.
The ideal walking shoe should be stable from side to side, well-cushioned and should enable you to walk smoothly. Many running shoes fit all of these criteria and for most people are acceptable for a walking program. However there are shoes specially designed for walking. These are generally lighter than running shoes.
Most important, whether you are wearing a walking or running shoe, is that it must feel stable to you. Either type of shoe is acceptable if it works well with your foot mechanics, providing cushioning and stability. Shoes should always feel comfortable and fit well in the store. Visit the shoe store late in the afternoon to allow for swelling. Wear the same socks to the store that you will wear while walking.
When the shoes are on your feet, the heel should be snug. If it slides in the store, it will slide while you are walking. You should be able to wiggle your toes in the shoe, and there should be one half to a full thumbs width between the end of the longest toe on your longer foot and the end of the shoe's toe box. Make sure your ankles don't roll in the shoes.
The shoes you try on should feel good immediately; you should never have to 'break in' a pair of athletic shoes. (For that matter, you should never have to 'break in' a pair of dress shoes either!).