In biking your hip flexors can get really tight because there's that forward motion just repeated," says Stephanie Duryea, C.P.T. “Working on hip flexor mobility and your hip mobility in general is really important.” Multidirectional leg swings are an effective dynamic stretch for warming up the hip joints and muscles in all planes of motion. Stand with your bike to one side, holding the seat for stability. Begin to swing your outside leg forward and backward, keeping it straight and extending the length of the swing each repetition. Repeat 10 times. Next, turn to face your bike and swing your leg side to side, stretching the outer hip and thigh muscles and the groin muscles. Repeat 10 times and then change positions to work the other leg.