First, find your maximum heart rate by running one mile, gradually increasing your pace until you’re at a full sprint for the last quarter-mile. Look at your monitor just before and just after you sprint the last leg—the highest number you see should give you an estimate for your max heart rate.
Once you have your max heart rate, divide your workouts into heart rate “zones.” Here’s a sample training plan designed to build endurance:
Monday: Jog an easy five miles at 65 percent zone (65 percent of max heart rate)
Tuesday: Run for one hour at 75 percent zone
Wednesday: Cross train at 65 percent zone
Thursday: Run five miles at 70 percent zone and incorporate 10 short intervals (20-30 seconds) at 95 percent of your max.
Friday: Jog easy five miles at 65 percent zone
Saturday: Run a five-mile tempo run at 85 percent zone
The underlying goal of training with a heart rate monitor is to run longer and faster, but with a lower heart rate. Test yourself by running a set course at a consistent pace. Then, four weeks after heart rate training, run the same course again, maintaining the same pace. If your heart rate is lower throughout the run, the training is working.