What really matters when choosing an athletic shoe, according to experts

A good-quality running shoe is essential, according to Dr. Damian Roussel, podiatrist and foot and ankle surgeon. Look for a light, flexible style that will absorb the repetitive impact of the foot hitting the ground.

Before beginning any new exercise program, consult your doctor. Stop immediately if you experience pain.

(CNN)Not all that long ago, people owned one generic pair of gym shoes, which they used for all sports and activities. Those days are long gone. Athletic footwear is a $16 billion business in the United States today. That figure is expected to grow rapidly over the next few years, as Americans buy multiple pairs of athletic shoes designed for different activities. But is it really necessary to have a closetful of sneakers, or is this all just marketing hype?

"All activities and sports require care in choosing specific shoes," said Dr. Bradley Schaeffer, a podiatrist and foot and ankle surgeon at New York City's Sole Podiatry. "You have to provide proper support to avoid creating or exacerbating conditions such as bunions, hammertoes, plantar fasciitis and ingrown toenails."
Working out in appropriate footwear also helps avoid overuse injuries, said Dr. Nelya Lobkova, a surgical podiatrist with Step Up Footcare in New York City. "It's especially important for the beginner or average participant, who is more prone to improper form."
    Athletic shoes may enhance your athletic performance, too, as they are designed to provide the appropriate support and stability for a particular activity — like running. Since running involves a repetitive forward motion, a good running shoe will be light with a flexible outsole, which helps keep the foot moving while absorbing the impact of the foot striking the ground.
      Hiking shoes, in contrast, have deeper tread patterns than running shoes to increase traction on uneven and natural surfaces, and they often come with higher uppers to provide ankle stability. Volleyball shoes, like many court shoes, provide support for movement in all directions, plus cushioning for the jumping that often occurs.
      But don't toss out your gym shoes just yet. You only need to purchase sport-specific shoes if you're participating in a given activity more than twice per week, according to the American Podiatric Medical Association. And lacing up a pair of cross-trainers may work just fine if your weekly workout regimen involves several different activities, says the American Academy of Orthopaedic Surgeons.

      Finding the right shoe

        Running, basketball, volleyball, hiking and tennis are some of the activities for which it's essential to have a sport-specific shoe, especially if you're a more serious athlete who wants to maximize your performance, said Dr. Damian Roussel, a podiatrist and foot and ankle surgeon with The Centers for Advanced Orthopaedics in Frederick, Maryland.
        But with so many brands on the market, how do you know which is the best shoe for you? Generally, it's the one that fits your uniquely shaped foot the best. Unfortunately, most of us aren't so great at determining proper fit.