Running ability builds when you are always workout-ready—that is, able to fully meet the challenges on the day's schedule. This obviously means from day-to-day your intensity will change, as a recovery day follows an intense day of speedwork, for example. As we've discussed in the past, if you are not running within a specific day's goal intensity-wise, your gains will be compromised, or worse, you will become injured.
One of the most effective ways to stay within your desired running intensity is to monitor your heart rate. By knowing at what percentage of maximal heart rate you are running, you are empowering yourself to adjust exertion in more subtle ways throughout the run. Common exertion goals correspond to specific heart rates.
For example, since the purpose of interval training is to increase VO2max, there are no gains to be made running intervals at a pace above your anaerobic threshold; the following table illustrates that your target heart rate for this type of workout, then, would be 80 to 89 percent MHR (max heart rate). (In the case of interval workouts, rather than running faster, optimize the time spent at this heart rate by adjusting the distances or the recovery times between intervals.)
Use the table to help place your effort and energy in the optimal zone for each workout:
Heart Rate | Breathing | Power | Tempo | Intensity | Exertion |
95-100 percent | Hyper | Strained | Very Fast | Very Uncomfortable | Maximum |
90-94 percent | Labored | Forced | Fast | Uncomfortable | Ragged Edge |
80-89 percent | Heavy | Pressed | Rapid | Tolerable | Threshold |
70-79 percent | Huffing | Relaxed | Quick | Comfortable | Steady State |
60-69 percent | Conversational | Held back | Slow | Very Comfortable | Light |
50-59 percent | Normal | Gentle | Very Slow | Soothing | Very Light |
For these heart rate percentages to have meaning, you must gain an accurate sense of what your MHR in fact is. To do this, you will need either to accurately take your own pulse, or wear a heart rate monitor. The usual formulas (for men, 220 - age = MHR bpm; for women, 226 - age = MHR bpm) are not acceptable estimates for MHR in trained runners. And studies of very fit athletes reveal an even wider gap between the general public's typical decreases in MHR with age and these elite runners, some of whom show no decrease at all in MHR for up to two decades. As Earl Fee writes in The Complete Guide to Running, "My own experience with a heart rate monitor indicates my MHR is of the order of 195 bpm but the formula above would predict only 150 bpm at age 70."
Fee offers several methods for determining MHR. Here is one:
When in good shape, do fast intervals after a thorough warm-up. Run 4 x 200 m or 3 x 300 m at 95 percent effort with 5 or 6 minutes of rest in between. Immediately after the last interval, measure the heart rate.
Without a monitor, you can check your pulse to determine heart rate. Place the fingers of your left hand on the artery at the top inside of your right wrist. When a pulse coincides with one of the seconds on your running watch, call this zero. Count all beats for 15 seconds, and multiply by 4 for bpm.