Science and technology advancements mean that our knowledge of fitness is constantly evolving. What was once standard practice, such as calculating maximum heart rate, can quickly become outdated and irrelevant. In this article, I will explain how to apply some of the newer formulas for calculating heart rate and intensity, and how these new tools may make it easier to help your clients build a stronger base of fitness.

New Formulas for Calculating Heart Rate

To determine maximum heart rate, the old method was to subtract your age from 220. From there you would simply calculate the remaining number by some percentage to determine your training heart rate or training zone. The new way (which is not at simple, but is more accurate) to calculate maximum heart rate corrects for both younger (below 25 years) and older (over 55 years) people. There are many new maximum heart-rate formulas to choose from, but ACE uses 208 minus (.7 * age). Thus a 50 year old would be 208 minus (.7 *50) or 208 - 35 = 173. The old formula gives a result that is only 3 beats lower, but at 70 years of age this difference is a significant 9 beats per minute.

The other major shift is in the use of the heart-rate reserve (HRR) or Karvonen formula. Subtract your resting heart rate from the number derived from the new maximum heart-rate formula described above—this will give you your heart-rate reserve. Multiple that HRR number by some percentage, say 70%, then add back the resting heart rate to get your training rate. For example, if you are 25, and your maximum heart rate was calculated at 190, and your resting heart rate is 60, then your HRR is 190 - 60 = 130. You then multiply this by .7 to get 91, and add back the resting 91 + 60 = 151, which as a 70% HRR training level for you. If you wanted to go to 80% HRR, your calculations would look like this: 130 *.8 = 104 and 104 + 60 = 164. So, you would train between 164 and 151 to be in the high end of your aerobic zone.

A Shortcut Method: The 180 System

The “180 system” was designed by Dr. Phil Maffetone, the physician who designed an aerobic-conditioning program for Mark Allen, arguably the greatest triathlete in the history of the sport. He believed that you could take 180 minus an individual’s age to figure out his or her maximum aerobic heart rate with some correction factors. The main corrections are needed for age and conditioning effect, or both.

If you don’t work out à subtract 5 beats



If you only work out 1-2 days/week à subtract 2-3 bpm



If you work out 3-4x/week, no change



If you work out 5-6x/week, no change



If you work out 7+/week for more than 1 year à add 5



If you are over 55 or under 25 à add 5



If you are 60 years or older or under 20 à add 5 more

So, for a 40-year-old, the calculation would be 180 - 40 = 140, while for the 25-year-old described earlier, you would add 5 beats for a 145 maximum aerobic training zone. The system allows the body to adapt to this heart rate and the speed will gradually increase until a plateau. Then you switch to anaerobic interval training as the primary modality. Dr. Maffetone warns it will take several months or even up to a year to see large differences in speed. Mark Allen shifted from an 8:15 minute/mile pace to a 5:20 pace at his 180-system heart rate. To this day, Mark has the fastest marathon split in the Hawaii Ironman at 2 hours and 40 minutes for his particular course.

The system is not meant to pound you into the ground, but rather let you feel refreshed and able to train the next day. In fact, the system requires you to do a high volume of training for maximum effectiveness. You should strive for two to three hours of training at this intensity in a week.

It should be noted that this is not the same as high-intensity interval training (HIIT) and may not elicit the super-fast results people expect. However, building the aerobic base slowly and surely across time is what 90 percent of all competitive endurance athletes still do.

If your clients are interested in training for endurance events or simply want to improve their fitness, visit www.acefitness.org/running for tools and resources that will help them reach their goals.