Over-striding can be a problem for runners since it can increase strain on the legs, throw off pacing, and increase risk of injury. Although over-striding mainly deals with the distance between your striking leg and your center of gravity, striking with too straight of a leg can signal an overs-stride. These leggings monitor how straight your leg is via a flex sensor. When the leg is too straight, the LEDs light up. When the leg bends, the lights turn off. Ideally, when running the lights will stay off if you have correct form and light up if you straighten your leg too much