Athletic shoes offer more than just style
You choose your running shoes based on the design, colour and maybe the brand, but you should also take into consideration the following factors.
Modern athletic shoes are designed to improve our mobility and movement and protect our feet and legs from injury.
The toe box should allow at least half to three-quarters of an inch of space between your longest toe and the front of the shoe, and of course ample width for your feet.
The sole - the rubber lining - has three parts, outer sole, midsole and innersole, and two important functions:
1. The sole absorbs shock from the ground, primarily at the midsole, which has the thickest and most flexible lining. Running shoes have midsoles that are thicker than other shoes.
2. The sole enables better grip on the ground so you don't slip, mainly with the outer sole, which is designed to suit the running surface. It's crucial in increasing the lifespan of the shoe.
The heel wedge found in some shoes is usually wide to offer support and balance.
The heel counter curves around the back of your heel. It should be stiff and fit well enough to reduce movement of the ankle and friction in up and down movements and while twisting the foot. It prevents ankle strain and sprains.
The Shoe Upper, made of leather or nylon, should be light and have good ventilation, and dry quickly if it gets wet.
The tongue and Achilles tendon pad should have a soft cushion to reduce friction in movement.
The arch support under the insole cushions the arch of the foot. It should be smooth and fit easily into the insole.
Getting shoes that fit is essential. Getting shoes designed specifically for your intended activity is important too.
Make sure you're wearing socks when you try on shoes at the store, and put the shoes through a few paces - movements you'll make when exercising.
Buy shoes in the afternoon or evening, when your feet tend to be larger, swollen from the day's activities.
The shoes should not be too tight. Your toes need room to stretch and should never get numb.
Athletic shoes have a life span in the sense that, after 800 kilometres, they lose a third of their ability to absorb shock. After 500km the cells in the rubber that lines the midsole are damaged and wrinkled. By 750km there might be tears in the cells.
You should thus get new shoes after every 800km or so. If you run 5km a day three times a week, get new shoes every year. The same applies if you do aerobics three to five times a week.
Assistant Professor Pasakorn Watanatada specialises in sports medicine and bio-mechanics at Samitivej Sukhumvit Hospital's Sports & Orthopaedic Centre, (02) 711 8181.