From the None issue of Runner's World
The Long and Short of It
Trail races are equal parts strength and speed. So as you build up to the big race, incorporate longer, slower runs as well as shorter, faster runs into your program.
Long run: Develop endurance and leg strength by shifting your weekly long run from roads to trails. To prepare for any race shorter than a 10-K, plan a long run that lasts around 60 minutes. For a 10-K or longer, work up to 90 minutes or more. Don't feel discouraged if you're running slower than you do on the roads; that's just the nature of trails.
Speedwork: A good trail racer possesses two forms of speed: leg speed and trail speed. Alternate the following two types of speed-training sessions every week as you prepare for your trail race:
1. "Leg speed" is that flat-out turnover of your legs, and it's best developed on the track, not the trail. You'll increase stride efficiency, sense of pace and anaerobic threshold by doing a weekly set of 6 to 8 x 400 meters or 3 to 4 x 800 meters at slightly faster than race pace. If the track just isn't your bag, try doing some hill work. Start with 4 to 6 repeats of a 200- to 400-meter hill, eventually working up to 8 or 10.
2. "Trail speed" is the ability to run at race pace over varying terrain. This is best accomplished with a 30- to 45-minute fartlek run on a trail that's not too rugged. (The term fartlek, or "speed play," was coined by the Swedes to describe speedwork on trails.)
Make it fun. Sprint from tree to tree. Run fast up a hill and jog the backside, or vice versa. There are no rules to fartlek workouts, only that one must push hard playfully. You'll work hard, but it won't feel like it. And you'll learn a lot about trail running in the process.
