Missing Your Max

Knowing your maximum heart rate is essential for effective aerobic workouts. But if you’re using 220 minus your age, you may be missing the mark entirely.

Is your cardio exercise program designed around heart-rate training? If so, great! Heart-rate training helps you make faster progress more comfortably and with less risk of injury and burnout. But how did you come up with your target heart-rate numbers? Did you just follow a simple formula like “220 minus your age”? If so, you may be undercutting your fitness efforts, because the truth is, most formulas can’t give you an accurate measure of your maximum heart rate (Max HR). In fact, simple age-based formulas may lead you entirely astray.

Method or Madness?

There are several methods for determining how hard you should be working during any given workout. Many of them are based on achieving targeted exertion levels (zones) defined by percentages of your Max HR.

Max HR is the highest heart-rate value you can achieve in an all-out effort to the point of exhaustion. Obviously, it’s rarely the goal of any workout to take you to a point of all-out exhaustion, but using percentages of your individual Max HR to determine the appropriate intensity for a given workout (or series of workouts) can help create more efficient and effective fitness routines. For example, working out at half your Max HR is great for improving your health and increasing your base level of fitness, while working out at 75 percent of your Max HR is a great way to improve your cardiovascular capacity and endurance.

So knowing your Max HR has its merits. But the best method for determining Max HR remains a hotly debated topic. For quite some time now, the best known Max-HR-estimating formula has been “220 minus your age.” While this formula does happen to prove accurate (or close to accurate) for some people, for others it turns out to be woefully off base.

Exercise physiologists have long questioned and researched this method’s reliability, and today there is a general consensus among informed fitness experts that Max HR cannot reliably be deduced using such a simple formula. The main problem is that Max HR is not influenced so much by age as by genetics. In fact, most people of similar age do not have the exact same Max HR.

For instance, exercise physiologists Jack H. Wilmore, PhD, and David L. Costill, PhD, authors of Physiology of Sport and Exercise (Human Kinetics, 2004) have reported that the Max HR of 95 percent of all 40-year-old men and women falls somewhere between 156 and 204 beats per minute. But that’s a big margin, particularly when you consider that most heart-rate zones (determined by Max HR) are carved out in ranges of 20 beats a minute or less. The lesson here: Estimate your Max HR wrong, and you can easily get your zones all wrong, too.

Testing for Accuracy

So if the standard formula can’t be trusted, then how do you determine your Max HR? There are basically three methods: good, better and best.

The “good” method is to use a slightly more complex formula that takes into consideration more personal variables than just your age. One formula (which can provide a more highly dependable, but still not perfect, estimate) is: 210 minus one-half your age; minus 5 percent of your body weight (in pounds); plus four (for men) or zero (for women). This formula has been tested on thousands of people and the results typically fall within five heartbeats of a person’s true Max HR. Of course, even this formula leaves something to be desired, but it beats the simple “220 minus age” hands down.

The “better” and more accurate method of estimating Max HR involves employing maximal and submaximal tests to evaluate your body’s reactions to real aerobic loads. The very “best” of these options employs sophisticated VO2-max equipment to pinpoint your body’s biochemical reactions at various stages of exertion. A maximal test (with or without specialized equipment) can give you a very good idea of your real Max HR, but because, by definition, it requires an all-out effort, it is very physically demanding, requires supervision, and it is not advised for people who are not already in relatively good to excellent shape. (If you are a candidate for a max test, see sidebar on how to conduct one.)

Submax tests are less taxing and can still offer a precise assessment of your Max HR – better than any formula. There are many submax tests to choose from (see our Nov. 2004 issue for examples). The Easy-Moderate-Hard Test, below, is ideal for people who already work out regularly. It’s easy to perform and doesn’t require any special equipment or supervision.

Making the Most of Your Max

Now that you have a more accurate Max HR, what do you do with it? Begin by working within the following five training zones: Zone 1: Healthy Heart; Zone 2: Temperate; Zone 3: Aerobic; Zone 4: Threshold; Zone 5: Redline. These zones (described below and in “The Zones Chart” at www.heartzones.com/images/maxhrchart3_04.pdf) cover a complete continuum of exertion. (Life Time Fitness members, note: A comparable zone chart will be available in clubs starting in January, and can also be found at lifetimefitness.com/heart_rate.)

You reap different benefits in each zone, so you want to choose your zones (and the amount of time you spend in each one) depending on your current fitness level and your goal for a given workout. The following are a few suggestions to help guide you toward choosing the appropriate intensity zone.

  • If you are just beginning a fitness program, spend the first two weeks in Zones 1 and 2 (50 to 70 percent of Max HR). After a couple of weeks add some time in Zone 3 (70 to 80 percent of Max HR). To reduce potential injury, it is important to progress gradually.
  • If you are already active, then use Zones 1 and 2 primarily for warm-up and cool-down and spend approximately 50 percent of your total cardio training time in Zone 3 (70 to 80 percent of Max HR), which can help improve aerobic capacity.
  • Once you have established a strong cardio base, devote approximately 15 percent of your total cardio training time to Zone 4 (80 to 90 percent of Max HR). This will help to raise your threshold. This is also where you burn the greatest total amount of fat calories in the shortest duration of time.
  • If you require speed to reach your performance goals, then devote about 10 percent of your weekly time in Zone 5 (90 to 100 percent of Max HR). Time spent in Zone 5 can improve your lactate tolerance and clearance. Too much time in Zone 5 can result in injury and burnout.

Keep in mind that your level of fitness is reflected not in having a high or low Max HR, but rather in the percentage of your own Max HR that you can sustain during a training session. The longer you can sustain a heart rate in the upper percentage of your Max HR, and the more comfortable you are while there, the fitter you are becoming.

Sally Edwards, MA, MBA, is the author of 20 books on fitness and sports, a professional triathlete and founder of Heart Zones (www.heartzones.com). Bev Robinson, BPE, BEd, MA, is a professional educator with the Calgary Board of Education with more than 15 years of teaching experience.

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