Is walking really a workout?

Is walking really a workout?

You may be surprised to learn that brisk walking can be almost as challenging as jogging. Here's why. When you walk at speeds faster than 3.1 mph, your stride length naturally increases (you don't necessarily want it to for efficiency but inevitably it happens). Lengthening your stride is inefficient because it requires additional energy to move your legs forward, which in turn requires more arm and torso movement, which leads to increased torso and hip rotation, which amounts to higher aerobic demands and more calorie-burning. This has been confirmed in the laboratory. The research shows that at maximal levels of exertion, oxygen consumption (the bottom line to cardiorespiratory fitness) is only slightly lower for racewalkers than it is for runners, and at submaximal or moderate-intense levels of exercise, oxygen consumption levels between race walkers and runners are almost equal. Racewalkers can reach speeds as high as 9 mph!

*extracted from medicinenet.com website