It is sometimes easier to run than to walk.
That sounds like a sphinxian riddle, but it’s actually a truth of human motion. As the human body reaches a certain speed, it becomes easier to run than to keep walking.
Researchers in NC State’s Human PoWeR (Physiology of Wearable Robotics) Lab believe they’ve discovered the reason for that apparent paradox. As a walker approaches a 4.5-mile-per-hour pace, running makes better use of an important calf muscle, making a jog more energy-efficient.
“The muscle can’t catch up to the speed of the gait as you walk faster and faster,” said Dr. Gregory Sawicki, assistant professor of biomedical engineering. “But when you shift the gait and transition from a walk to a run, that same muscle becomes almost static and doesn’t seem to change its behavior very much as you run faster and faster, although we didn’t test the muscle at sprinting rates.”