Sneakers on springs.

Did you ever wish you had more spring in your step so you could run faster and farther? Check out these new spring-loaded running shoes. Instead of plain rubber soles, they have springs in their heels.

The spring isn't just the latest fashion statement, says Alvaro Gallegos, president of Z-Tech, the company that designs "Recoil" running shoes. "It's a shock absorber." The spring cushions your step, reduces the impact on your legs and feet, and gives you an energy boost, he says.

When you run, your legs hit the ground with a force three to four times your body weight. The ground pushes back with an equal force. That impact can ultimately lead to leg and foot injuries, like shin splints (muscle pain in the shins) and bruised heel bones. Gallegos' own injured foot inspired him to dream up the spring shoe six years ago.

If you're wearing spring shoes, your feet compress the springs with each step. The springs -- not the ground -- absorb most of the shock, and store it as potential energy. When you push off, the stored potential energy propels you forward with extra power, Gallegos says.

Do the shoes really protect your legs and feet from injury? Jeffrey Jensen, a podiatrist (foot specialist) from Denver, Colorado, wore new spring shoes in four 42-kilometer (26-mile) marathons last fall. When you walk, he says, you feel wobbly, like walking in high heels. But when you run, "it feels like a normal running shoe," he says. And Jensen says he didn't feel as fatigued.

So the shoes may reduce shock and cut down on injuries, but they won't help you run any faster. What may run fast is the money pouring out of your wallet: The shoes cost $139 a pair.