Recent studies show that running backward improves fitness. It may result, though, in falling.
The biomechanics of running backward are, unsurprisingly, almost exactly the inverse of the forward version.
According to a 2011 study, when runners stride ahead, they typically strike the ground near the back of the foot and roll onto the front, coiling muscles and tendons and, in the process, creating pent-up energy in the tissues that is forcefully released as the foot pushes off.
Backward runners do not generate the same kind of pent-up energy, the study found. Instead, to complete each stride, they use more leg muscles than in forward motion and burn about 30 percent more energy to go at the same pace as when running forward.
Because it is relatively strenuous, backward running can be effective in building fitness. 2014 study found that even among walkers, going backward resulted in greater improvements in physical performance than a comparable amount of forward walking.
But there is a literal downside. People often trip, stumble or slam into objects and other people while running backward.
On balance, though, the benefits can outweigh the risks