Spice up your treadmill workouts--go backward. (The Crosstraining Report).

Whether you are a treadmill devotee or you find treadmill workouts a bit boring but necessary try mixing it up when you run the ramp. Studies have shown that the energy costs of running backward are greater than running forward, and now a new study from Harvard University explains why your body must work harder to run in reverse.

Four well-trained male runners ran backward and forward at eight different treadmill speeds while researchers measured VO2, as an indicator of metabolic rates and foot-ground contact. At all speeds, both metabolic rates and ground force application rates were greater for backward than for forward running. At a higher speed, the volume of muscle used per unit of force was greater for backward running. In order to run backward, you spend more time in the air, your feet hit the ground faster and you have to use more muscle power to make it happen. Therefore, the energy cost (the amount of oxygen you process and calories you burn) is up to 32% higher to run in reverse than to run forward.

Adding backward intervals can increase the intensity of your workout significantly and challenge the systems that contribute to balance for a double benefit. While backward running may not significantly improve your forward running performance, it can help improve overall fitness by training different muscle groups as in any crosstraining effort. But stick to the track or the treadmill for backward workouts--seeing where you're going is more than 32% more difficult compared to running forward. Always start your backward runs at slower speeds and use caution as it can be awkward and difficult.

(Journal of Experimental Biology, 2001, Vol. 204, No. 10, pp. 1805-1815; Journal of Applied Physiology, 1999, Vol. 86, No. 5, pp. 1657-1662; Medicine and Science in Sports and Exercise, 1998, Vol. 30, No. 9, pp. 1419-1423; Pfiugers Archives, 2001, Vol. 442, No. 4, pp. 542-546)