If you want to become a better off-road runner, shorten your stride and strengthen your abs, says Brian Metzler, the editor of Trail Runner magazine.

A short stride is more efficient on gnarly terrain because it minimizes energy-wasting slips. As for the abs, Metzler says your body works them overtime to maintain balance and to brace against shocks on uneven trails, "so do your sit-ups, crunches, V-sits, whatever. Strengthening your stomach is the best way to make the transition from road running to trail. If you haven't been doing your ab work, you'll wind up hurting."