Cross-country running is a fall varsity sport at most high schools and colleges in the United States. Typically, high school boys and girls compete over 5-km, or 3.1-mile, courses while college men and women race 6-km and 10-km distances, respectively. A grueling endeavor thanks to hills, rough footing and frequent nasty weather, cross-country is an aerobic activity, and participants may therefore benefit from using heart rate monitors or HRMs. Available online and at specialty running stores, HRMs help ensure you're training at the proper intensity level.
Heart Rate Basics
Data from a heart rate monitor are not useful unless you know your maximum heart rate, or MHR. You can estimate this by warming up and doing three two- to three-minute high-intensity runs up a moderate incline, jogging back down to the start immediately after each. If you run the first repeat nearly all-out and run the last two as hard as you can, you should reach your MHR during the second or third repeat. According to exercise physiologist Pete Pfitzinger, your MHR may decline by as much as 7 percent as you become fitter thanks to your heart's improved efficiency. MHR also declines with age.
Heart Rate Reserve
To determine effective training zones based on your "max," use the heart rate reserve method. Your heart rate reserve, or HRR, is the amount by which your heart rate can increase from total rest to peak effort, which is simply your MHR minus your resting heart rate, or RHR. To determine the heart rate corresponding to a given percentage of maximum effort, multiply this percentage, expressed as a decimal, by your HRR and then add your RHR to the result. For example, if your MHR is 200 and your RHR is 60, running at 80 percent using the HRR method means running at (0.8)(200 - 60) + 60 or 172 beats per minute.
Training Zones
In training for cross-country, you do mostly easy to moderate aerobic running, a good amount of hill running, and lactate threshold training, which teaches your body to tolerate the buildup of lactic acid that occurs in races and also helps you deal with pace fluctuations. Pfitzinger suggests cross-country runners do lactate threshold running at 76 to 88 percent of HRR, long aerobic runs between 70 and 76 percent, and recovery runs between more specific harder efforts at under 70 percent. The utility of a HRM lies not only in keeping you working hard enough on hard-workout days, but also in ensuring you run easy enough on recovery days.
The VO2 Max and HRM Limitations
Brian MacKenzie, a longtime coach with U.K. Athletics, notes that above a certain intensity level, focusing on pace becomes more important than focusing on heart rate, since in a race you will not be running to achieve a target heart rate but instead to compete. He suggests that at efforts above 90 percent of VO2 Max heart rate, which is the heart rate achieved during an all-out run lasting approximately 10 minutes, you try to hit certain times in repetition training -- for example, 3 x one mile in 7:00 with jogs in between for a high school runner hoping to run 5 km in about 22 minutes.
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