When historians look back at the last fifteen years of the 19th century, they’ll say, "The heart rate monitor was far and away the greatest invention of its time." Well, perhaps I’m exaggerating the importance of HRMs just a little... OK a lot!

But for the endurance athlete, the HRM is certainly a revolutionary tool. It’s responsible for a new accuracy and specificity in coach/ athlete communications that’s not possible by simply describing workouts in terms of "feel." But you might say, "I’ve always trained by feel and it’s worked well for me all these years." I did quite well without a HRM for the first 15 years of my athletic career as well. But now that I use one for almost every training outing, and occasionally in races, I have much more control over the result of my training and racing. By keeping track of the heart rates I’ve seen during specific workouts, I have reference points for overtraining, undertraining, and the quality of my hard efforts. I’d like to think that my ability to sense I’m doing just the right thing in training is infallible. In reality, it’s not. Sometimes when I have that euphoric feeling after a great race, I feel indestructable. I know I’m supposed to do some easy recovery workouts, but what I really want to do is hammer! Not smart. Fortunately, I’m wearing my pulse monitor and I know I’m not supposed to go above a heart rate of XXX on recovery days. I back off so I don’t leave my next fantastic race in training. At other times, I may be doing a hard time-trial effort, but I just can’t get going. I look down at my pulse monitor and it’s 10 beats too low for my perceived effort level. In this case I know it means I’m overtrained and need a break.

Determine Your Maximum Heart Rate

This is the critical first step so that you can use percentages of your maximum heart rate as a guide. Few athletes actually see their true maximum heart rate, so initially there may some guesswork involved in your calculations. Here’s the rule for determining your maximum heart rate if you fit the average profile: For men subtract your age from 220 beats per minute, for women subtract your age from 227 beats per minute. This works well for about 50% of the athletic population, but the values for the other 50% can vary by as much as 10 beats on the low side or 24 beats on the high side. Most athletes only get within 3 to 5 beats of their maximum while sprinting at the end of a short race. Some may get even closer to max when doing longish interval repeats on the track. The highest heart rate I’ve ever seen for myself occurred while doing half-mile repeats in 107 degree heat at a New Mexico training camp. Yes, that was nuts. Anyway, it may take a few weeks, or even months, to venture an educated guess for your maxHR. If the typical profiles clearly don’t work for you, I recommend adding 2 to 5 beats to the highest heart rate you’ve ever seen, for an estimated maximum. Judging by the traditional rule, your maxHR should drop by 1 beat every year. I doubt this is true for endurance athletes over thirty who have been in continuous training. I’d guess the drop is only one-half of a beat per year, or less.

Determining Percentages of MaxHR

This is fairly easy once you have figured out your maxHR. There are two methods: 1) A percentage based on a pulse range from zero to maxHR. 2) A percentage based on your pulse range from restingHR to maxHR.The latter method was named the Karvonen method after its Scandinavian physiologist inventor, and this is the preferred method for athletes. Subtracting my resting heart rate from max makes sense, since I hope my heart rate never drops to zero (at least not for the next 35 years or so). Method ≠ gives a narrower range, and it’s the only one I use when I communicate with athletes about heart rate percentages. Here’s how to calculate your percentage of maximum heart rate following the Karvonen method: We’ve already found what we believe to be our absolute maxHR, now we need to find our resting heart rate. The number I like to use is the lowest pulse I’ve ever counted during the day; sitting very quietly and totally relaxed. This "daytime" pulse may be a few beats higher than you may have counted lying still in bed upon awakening. Once you have arrived at this number simply subtract it from the maxHR number. Now to find the range in 10% increments, divide this maxHR - restingHR number by 10. If you need 5% increments divide the same number by 20. Here’s an example: 190 beats per minute max HR minus 50 beats per minute restingHR = 140 beats per minute. Divide 140 by 10 = 14 beats for each 10%. So if I want to figure 70% of my maximum heart rate, I multiply 14 x 3 (100% - 70% = 30%) and I get 42 beats per minute. I subtract 42 from 190 and get 148 beats per minute for 70% of maxHR. This may seem like a pain, but all you really need is to do the calculations once and memorize the numbers at 60%, 70%, 80%, 90%, and perhaps 75%, 85%, and 95% as well. And make sure you know which HR percentage method a coach is referring to when you discuss training plans. Now that you have a formula to find these percentages, how do they fit into a training plan?

Heart Rate Percentages and Training Effect

Each heart rate range has a distinct effect for your training. I’ll describe what pulse range is appropriate for each type of workout:

n 55% to 65%. This is an effort level considered appropriate for very easy training and recovery days after tough training or race efforts.

n 65% to 75%. This is the range for maximum aerobic training benefit, and moderate "base" training that is not especially stressful to the body. This range is also allegedly the best to develop your metabolism’s fat burning capability. The majority of your training should be done in this range.

n 75% to 85%. This is mild tempo training that helps to build your muscular/skeletal foundation for the rigors of racing. This range is especially valuable during the early pre-season phase when you need to "toughen-up" in preparation for higher intensity training and racing.

n 85%. This is considered fast tempo training. It’s not quite race pace (except for very long races) but it simulates race efforts without the need for as much recovery afterwards. This intensity should be performed as late pre-season training, and as a substitute for races when there are none available.

n 85% to 95%. This is the race effort range. During a PR 5k race effort, you may find yourself holding 95% for the second half of the race. For a fast 10k you’ll probably be in the 90% to 95% range for your best effort. Also, when you do speedwork on the track you should expect to see a heart rate at or above 90% of max for much of the workout.

Some Finer Points of Training with a HRM

Your heart’s response to exercise is directly proportional to the amount of muscle mass being used for the activity. In other words, a sport that involves more muscle to propel your body, will demand higher heart rates. This is why observed maximum heart rates while running are typically 8 to 10 beats higher than cycling. While running or cycling at identical perceived effort levels which are below maximum, the same 8 to 10 beat difference will apply.

Most pulse monitors have a lag time of 4 seconds between receiving the signal, and the number you see, which is averaged over 4 seconds within the unit. There’s also a lag time for your heart’s reponse to stress during warm-up and race starts. If you sprint-out in a race hoping to see your target HR during the first quarter mile, you could be in serious trouble later. This applies to any training or racing outing, since your pulse will gradually creep up as you warm-up, and also as fatigue sets in. When describing a certain effort level by percentage of maxHR, the number is meant to be for a flat stretch of road as an average over the duration of the workout. A pulse 5 to 8 beats higher is acceptable on tough hills as long as it drops back down afterwards. Also, when attempting an even or negative split for a training outing or race, expect to see higher numbers for the second half of the workout. If I want to maintain an average of 150 bpm over my entire workout -- with even pacing, I’ll stay in the high 140s for the first half and low 150s for the second half.

Interference from other HRM units is a possibility when other HRMs are nearby. When you’re training or racing with others and you see a heart rate value that just can’t be right, consider the interference possibility. It can only happen in situations where you are literally inches away from another athlete, or when the battery in their transmitter is stronger (perhaps fresher) than yours.

I recommend using your heart rate monitor along with your own finely tuned sense of perceived effort to assess your workouts and races. When you learn to combine the information from both sources effectively, the knowledge gained will allow you to maximize your athletic time and energy.