Opt for trail-running shoes over road runners. They provide better traction and rock protection and have less cushioning, which suits soft dirt surfaces and keeps your feet lower to the ground for greater stability.
Dress right. Wear synthetic running shorts or pants, a wicking top, and, if needed, an ultralight shell, a hat, and light gloves. Pack essentials. On runs longer than 45 minutes, carry fluid in a bottle belt or hydration pack. Also take energy bars or gels—you want about 100 calories an hour—a phone (if there’s service), and a map.
Seek out dry, packed-dirt trails. Avoid rocky, rooted, overly steep, or muddy paths, which invite injury. Typically, sun-baked paths over hills or up valleys offer better conditions than, say, cliffy trails to high points.
Set realistic goals. You’ll move slower and cover less distance than you would on asphalt. On many hill trails, 6 mph is an aggressive pace.
Consider getting a heart-rate monitor. Most new trail runners go out too hard, ratcheting their heart rate beyond an effective training zone. To best build long-haul endurance, maintain a conversational pace—one at which you can talk comfortably. It’ll be slower than your pavement pace, and roughly 60 to 70 percent of your max HR.
Perfect your posture
Don’t “trunkle”—or hunch over. Limit fatigue in your core by keeping your chest out and your torso straight, relaxed, and in line with your hips and feet. Bend your elbows at 90 degrees, and swing your arms in a straight line parallel to your torso.
Vary your foot plant. On steep uphill sections, run on your toes and the balls of your feet. For moderate angles, choose between toe, midsole, or heel-to-toe strikes, whichever feels better (or alternate among them). For downhill, toe and midsole plants usually work best.
Don't bounce. Your legs and arms should mostly move forward, not up and down. If that tree ahead is bobbing, you’re wasting energy.
Plant your feet quietly. This way, muscles control speed, not joints.
Shorten your stride on steep or insecure descents. Land with your weight over your feet to reduce the risk of a fall.
Look three steps ahead to anticipate the terrain.
Beware of slick surfaces. In wet conditions, step over rocks and roots.
Walk for short stretches or wherever the trail gets too steep or slick.
Build your miles gradually. To avoid overuse injuries, start with once or twice a week and progress to no more than four or five times a week. Increase distances by only about 20 percent a week. If your run leaves you with pain worse than a little stiffness and that lasts more than a day or two, take a few days off and dial back your distance.