We all know “that guy” or “that girl” at the gym — the one you see running as fast as he can on the treadmill, gripping the machine for dear life, probably thinking, “The faster I run, the more calories I will burn, the more weight I will lose! Yes, we’ve all seen that guy. Perhaps we’ve passed him by, thinking that he’s crazy. Perhaps we’ve been on the treadmill next to him secretly trying keep up, or perhaps we have even been that guy.
Then there are the things “they” say. Well, you know, they say it’s all about “calories in, calories out.” They say the harder you work, the more calories you burn. They say you should slow down to hit your target heart rate for best results. Who are “they” anyway?
Let’s clear up some confusion about where your heart rate should be while exercising. The term target heart rate (THR) refers to the ideal intensity level at which your heart is being exercised, but not overworked. The American College of Sports Medicine recommends performing physical activity at a range between 65-85 percent of maximum heart rate (MHR) three to five times per week for 20 to 60 minutes at a time. Your MHR is the fastest rate at which your heart is able to beat in one minute. The simplest formula for estimating your MHR is to subtract your age from 220 (e.g., 220-40 years = 180 beats per minute). You should not go over this number for more than one minute, and theoretically, you should not be able to sustain this without passing out even if you tried (I do not recommend trying). Individuals who engage in intensive endurance training or high-performance athletes may benefit from working above the THR range. These individuals should consult an exercise specialist for guidance.
Your anaerobic threshold (AT) is the point at which you stop burning fat while exercising. Physiologically, the muscles start using more oxygen than the body can transport, and as a result, lactic acid builds up. Exercising below your AT develops your aerobic capacity, helps burn unwanted fat, and improves health parameters such as blood pressure, cholesterol and blood sugar. Some people call this the “fat burning zone,” which can be estimated by taking 65 percent of your MHR (180 x .65 = 117 bpm). Although you are not burning as many overall calories, and some would say they feel like they are barely working out, you are burning a higher percentage of calories from fat.
So why would anyone want to stop burning fat and work above this number? Working at a higher intensity such as 85 percent of MHR (180 x .85 = 153 bpm) will allow you to burn more calories and create a larger caloric deficit needed for weight loss. And the best of both worlds? Work at 65 percent so that you are “fat burning,” but do so for a longer period of time so that you burn more fat and calories. Work in this zone one to two days per week for 45 minutes to an hour.
But that won’t be enough if you expect to improve your physical fitness and sustain weight loss. To do this, you will need to spend some time working at 80 to 85 percent of your MHR. Work in this zone two to three days per week for at least 30 minutes or you can work in intervals by bringing your heart rate up to 85 percent for one minute and back down again to 65 percent for two minutes. Repeat this for at least 30 minutes.
Remember that these numbers are merely estimates, and everyone’s body works differently. This is especially important for people with known heart disease or who take medications for blood pressure or heart arrhythmias. These individuals may have a lower THR range and would want to get clearance from their physician before they begin any exercise routine. On the opposite spectrum are people who are regular exercisers who may have a more conditioned body, and may have a higher THR range than the calculation predicts. The heart, like other muscles, becomes stronger and more efficient with work, creating the need to go beyond this number to achieve the same results.
If you are unsure about where your THR zone lies, visit us at the Prevention Center to check if you are on medication that can affect your heart rate and get an individualized exercise prescription in our multifunctional fitness facility. We work in a comprehensive team that specializes in the prevention of cardiometabolic disorders, diabetes and obesity. We can have our physician do a thorough workup and evaluation to clear you for exercise if needed. If you are trying to lose weight, you can work with our dietitian/personal trainer for nutrition and exercise coaching, in addition to our behavioral specialist to help you stick to your health lifestyle changes for good! Call us at (312) 942-3133 to make an appointment.