Login or Register

The TMAX for a Heart Rate

Jun 14, 2011 | By Linda Tarr Kent
The TMAX for a Heart Rate
Photo Credit Jupiterimages/Brand X Pictures/Getty Images

Calculating your target maximum heart rate, or TMAX, for a workout will help you work at a level that optimizes fat and calorie burn as well as athletic performance. There are many factors that go into calculating your TMAX heart rate. Unfortunately, while there used to be a standard and fairly simple formula for finding your TMAX, new scientific evidence reveals potential inaccuracies in this formula. These days, many formulas are proposed for finding your TMAX.

Standard Formula

The standard formula is based on two equations. You take 220 and subtract your age to get your maximum heart rate. Your target heart rate zone is 50 to 85 percent of this number. If you want to work at the top end of your target zone, you work at the 85 percent level. That means a TMAX is 170 beats per minute if you are 20, 153 if you are 40 and 136 if you are 60, notes the American Heart Association. This formula is widely used to test athletic fitness and is taught in physical education classes.

Women's Formula

The standard formula appears inaccurate for women, according to M. Gulati, lead author for a study published in the journal American Heart Association journal "Circulation." If you are female, you should actually use 206 minus 88 percent of your age to calculate your maximum heart rate, the first step in achieving your TMAX. You still use the 85 percent level for TMAX. That puts you at 160 beats per minute if you are 20, 145 if you are 40 and 130 if you are 60.

Athlete's Formula

If you are a trained athlete, such as a runner or weight lifter, your heart can pump more blood than a sedentary person's can so it does not need to beat as often. A better formula for you to find your maximum heart rate is 202 minus 55 percent of your age if you are male and 216 minus 109 percent of your age if you are female. You then take 85 percent of this number to get your TMAX. If you are male that makes your TMAX 162 if you are 20, 153 if you are 40 and 144 if you are 60. If you are female that makes your TMAX 165 at age 20, 146 at age 40 and 128 at age 60.

Another Standard Formula Proposal

Yet another theory found in the "Journal of Exercise Physiology" suggests using this formula to find your TMAX: Take 85 percent of 205.8 minus 68.5 percent of your age. That puts you at 163 beats per minute if you are 20, 152 if you are 40 and 140 if you are 60. However, this formula has a margin of error of 6.4 beats per minute, which is extremely large, says sports medicine doctor Gabe Mirkin, author of "The Healthy Heart Miracle."

Leg Strength Factor

All of these formulas may be too simplistic because they don't take your leg strength into account, Mirkin says. Calculations for TMAX really need to factor in the Bainbridge reflex to get an accurate number. According to this theory, your leg muscles squeeze against the blood vessels near them to pump your blood from the veins in your legs to your heart when you contract them. That means your leg muscles cause your heart to beat more forcefully as they pump increased amounts of blood toward your heart. When your legs become stronger, they can pump more blood. This factor makes it extremely hard to create a maximum heart rate formula that truly works across the board, Mirkin says.

VO2 Max

You may find your maximum heart rate by measuring factors like your ventilator threshold, or VO2 maximum. However, even this can be problematic. If you perform the measurement in a laboratory setting, it is likely to come out differently than if you perform it in a real exercise or competition setting, says Katherine Semin, lead author for a study published in the "Journal of Sports Science and Medicine."

Considerations

Even organizations that advocate the old formula for maximum heart rate caution that there are factors that will alter your TMAX heart rate. For example, some high blood pressure medications will do so. That means you'll need to consult a health care provider to gain help finding your target heart rate. Also, the American Heart Association cautions that you should not work at your TMAX right away when you start a new exercise program. It's best to aim for the lowest part of your target heart rate zone for the first couple of weeks and gradually build up to working at your TMAX over a six month time frame. Always consult a doctor before starting or ramping up an exercise program, however.

References

Article reviewed by Adela McKay Last updated on: Jun 14, 2011

Must see: Photo Galleries

Member Comments