{"id":217947,"date":"2025-12-30T10:57:17","date_gmt":"2025-12-30T10:57:17","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/217947\/"},"modified":"2025-12-30T10:57:17","modified_gmt":"2025-12-30T10:57:17","slug":"heart-rate-zone-training-math-is-flawed-for-women","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/217947\/","title":{"rendered":"Heart Rate Zone Training Math Is Flawed For Women"},"content":{"rendered":"

These days, everyone from the average Susan to the hardcore data-loving wellness enthusiast has the technology to track just about anything in the name of self-optimization. <\/p>\n

A ring wearable<\/a> tells you how many minutes of deep sleep you got last night. An app determines from an uploaded photo how many grams of protein were in your pancakes. Your watch can program your workout based on how much stress it detects in your body. These devices generally use algorithms and equations that help us live and train better, smarter, faster, and stronger, right? <\/p>\n

Well, not always. While these tools offer helpful insights, their data isn\u2019t infallible. And, sometimes, it can lead users to overlook what their own bodies are trying to tell them. That tension becomes especially clear with heart rate zone training, a popular five-tier system that endurance athletes use to measure effort and fine-tune performance.<\/p>\n

The well-known formula is simple enough: Subtract your age from 220 to find your maximum heart rate. From there, each \u201czone\u201d represents a percentage of that HR max number, from zone 1 (easy effort) to zone 5 (max effort). Zone 1 is when you train at 50 to 60 percent of your heart rate max number, a level that should feel casual and easy, like you could sustain it forever. Zone 2 is generally 60 to 70 percent of your HR max, zone 3 is 70 to 80, and zone 4 is 80 to 90 percent. Lastly, zone 5 is 90 to 100 percent of your heart rate max, so you\u2019ll feel winded, like you\u2019re at your most intense effort.<\/p>\n

The issue: Many runners (particularly women) report that their fitness trackers tell them they\u2019re exercising in a higher zone, even though their breathing is steady, their legs feel strong, and they can hold a conversation. If their body says they\u2019re fine, why do their watches insist otherwise? <\/p>\n

Turns out, the heart rate zone training system, as it\u2019s been sold for decades, is built on flawed math, according to research and top cardiologists. And those flaws hit women the hardest.<\/p>\n

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JEAN-YVES LEMOIGNE<\/p>\n

\"soundHow Women Got Subtracted From The Math <\/p>\n

Most fitness trackers and gym equipment still rely on that simple formula of 220 minus age to determine HR zones. The equation is often traced back to research published in 1958 in The British Medical Journal that looked at the correlation between occupation and coronary heart disease, as well as research from 1968 in the Bulletin of the New York Academy of Medicine on physical activity and heart disease prevention. <\/p>\n

Back in the \u02bc50s and \u02bc60s, many studies on exercise were done on young men who were getting physiological stress tests before serving in the military, says cardiologist Martha Gulati, MD<\/a>, who specializes in women\u2019s hearts and is the immediate past president of the American Society for Preventive Cardiology. Based on that fact alone, they\u2019re likely not super accurate for people of all ages and sexes. <\/p>\n

Subsequent studies on heart rate during exercise expanded to include broader populations of healthy people as well as people in the hospital undergoing clinical testing. In the hospital-based studies, researchers observed that \u201cheart rate variability could be used to predict who did well versus who didn\u2019t do well after a heart attack,\u201d says Aaron L. Baggish, MD<\/a>, a professor of sports cardiology at the University of Lausanne in Switzerland and the founder of the Cardiovascular Performance Program at Massachusetts General Hospital.<\/p>\n

Over time, scientists compiled data from this array of studies to estimate \u201cmaximum heart rate,\u201d scaling it into the now-popular equation of 220 minus age\u2014which many experts in the field believe to be an oversimplification that ignores biological differences. <\/p>\n

That one-size-fits-all approach assumes that everybody\u2019s heart responds to exercise the same way, which is not true: Your HR max \u201cis not a trainable number and is sort of genetically predetermined, and so it\u2019s really different for everybody,\u201d says sports cardiologist Ankit Shah, MD<\/a>, the founder and president of Sports & Performance Cardiology, an associate professor of medicine at the Georgetown University School of Medicine, and the team cardiologist for USA Swimming. For instance, two runners of the same age might experience dramatically different heart rate fluctuations during a run. So, \u201cif you\u2019re using it for individualized personal assessment to create training guidance, it\u2019s not going to be helpful,\u201d he says.<\/p>\n

\"graphicUpgrading The Equation<\/p>\n

Still, this dated equation became gospel despite having limited basis in individual biology. Over the years, researchers tried coming up with better equations and refining the way we calculate HR max. But it wasn\u2019t until 2010 that a formula for heart rate max was finally developed specifically for women, created by Dr. Gulati and published as a study in Circulation. <\/p>\n

She questioned whether the prior data from male subjects could be applied to women and set out to determine how women\u2019s hearts respond to cardio exercise. \u201cI just wondered how could a woman be exactly the same as [a man], which is really why I actually even did the study,\u201d she says.<\/p>\n

Dr. Gulati and her colleagues studied nearly 6,000 healthy women from the Chicago area between the ages of 35 and 93. Each participant did a treadmill test using the Bruce protocol, the most common clinical stress test, in which speed and incline increase every three minutes to gradually raise heart rate. <\/p>\n

Using the data collected, the team looked at the relationship between age and peak heart rate, which is an inverse linear relationship (as you get older, your max heart rate will decrease). They created a regression equation (a method that identifies relationships between variables) and developed a new equation \u201cbased on age for what their peak heart rate was,\u201d Dr. Gulati says. The result? A more accurate formula for women\u2019s max HR: Multiply your age by 0.88, then subtract that from 206. <\/p>\n

Dr. Gulati\u2019s equation fixed one problem, yes, but it also revealed another issue: that a single number could define how hard a person should train was problematic to begin with. <\/p>\n

The new approach was a step in the right direction. Still, \u201cusing population-based estimations to come up with your true maximal heart rate is fraught with error, especially in women, because it\u2019s such an individualized measure,\u201d says Dr. Baggish. Dr. Gulati, too, acknowledges that even with her equation, there were participants in her study who had heart rates well above and below the average, which is entirely normal.<\/p>\n

\u201cIn general, women tend to have a slightly higher true peak heart rate at any given age than men, but they also tend to have more variability,\u201d Dr. Baggish says. The reason for that variability isn\u2019t fully understood, but women\u2019s higher peak heart rates are thought to stem from the fact that they have smaller hearts compared to men. Heart rate reflects the speed at which blood moves throughout the body over the course of a minute. So, \u201cthe smaller your heart, the more times your heart has to pump to deliver that desired blood flow,\u201d he explains.<\/p>\n

That a single number could define how hard a person should train was problematic to begin with. \u2014Dr. Gulati<\/p>\n

And that variability means that every max heart rate number comes with a margin of error. When you calculate your HR max with any of these equations, you\u2019ll also get a confidence interval\u2014a range that represents how much individual variation exists within the population the formula was based on, Dr. Baggish says. Different studies show a standard deviation (or variation in the population\u2019s heart rates) of 20 to 26 beats per minute. (Dr. Gulati\u2019s research found there were multiple women in the same age group who had maximum heart rates that were 25 beats above or below the average.) <\/p>\n

So, technically, a 40-year-old woman\u2019s max heart rate could fall anywhere between 146 and 196. What her smartwatch reads as zone 3 might actually be more like zone 2 for her\u2014or vice versa. \u201cThat\u2019s normal,\u201d Dr. Gulati says. \u201cWe are not identical human beings.\u201d <\/p>\n

Because of this wide range, \u201ctrying to dial [your HR max] to a precise number that you can use is very, very difficult,\u201d Dr. Baggish says. A heart rate maximum is \u201cjust simply not something we can actually accurately capture in a single equation.\u201d <\/p>\n

Still, using an equation like Dr. Gulati\u2019s provides a helpful starting point, a ballpark estimate of where your HR max might be for your age. But from a training or performance perspective, \u201cthere\u2019s no benefit to using an equation,\u201d Dr. Shah says. The numbers you calculate are only estimates, not prescriptions. <\/p>\n

So why is that original equation still the widely accepted standard? For one thing, 220 minus your age is just plain easy to remember. Plus, heart rate zones as a whole have become commercialized\u2014a marketing tool to encourage people to purchase wearables to track and optimize their fitness. Technically, no one needs to use a device if they don\u2019t want to, says Dr. Baggish. Trackers supposedly make it possible to find out, with the click of a button, your peak heart rate, how much you slept last night, and how stressed you are. That is a great marketing spiel, but it isn\u2019t based on accurate science. <\/p>\n

Finally, there\u2019s a lack of education on the differences between the sexes when it comes to heart rate, Dr. Gulati says. Even the American Heart Association still gives blanket recommendations for heart rate zones using 220 minus age, without taking sex or individual differences into account. Dr. Gulati isn\u2019t entirely sure why the organization doesn\u2019t use her equation for women instead. \u201cThey published our work, but I guess the math is easier using an inaccurate formula,\u201d she says. <\/p>\n

Related Stories\"a<\/p>\n

JEAN-YVES LEMOIGNE<\/p>\n

\"audioThe Zones Are Up For Debate Too<\/p>\n

There\u2019s also controversy among researchers and experts in the health and fitness space about how many exercise intensity zones really exist. Open up your fitness tracker\u2019s heart rate training mode and you\u2019ll probably see five neatly color-coded zones. But depending on who you ask, there can be more\u2014or fewer\u2014and it might not even depend on your heart rate. <\/p>\n

For Dr. Baggish, the conversation around the zones has gotten overly complicated, even misleading. He doesn\u2019t buy into the five-zone system, arguing that it\u2019s based on arbitrary percentages rather than actual human physiology. He supports a model with three exercise intensity zones, which was established in research decades ago and is derived from how the body produces and processes lactate\u2014a fuel created during exercise\u2014in the blood. <\/p>\n

Essentially, the harder you exercise, the more lactate your body produces. How efficiently you\u2019re using that lactate determines which of the three physiological intensity zones you fall into. These zones are rooted in measurable biological markers, not just math, Dr. Baggish says.<\/p>\n

At a relatively easy or moderate intensity, your blood lactate level doesn\u2019t change and your body is using every bit of lactate it produces. In this zone, you can speak 8- to 10-word sentences at a time and you\u2019re comfortably breathing while talking; it\u2019s a conversational pace. As effort increases, you enter the heavy zone. Your blood lactate starts to increase, but \u201cthe body can still continue to use it and maintain it at a steady state,\u201d Dr. Baggish says. In this zone, you can still talk, but it\u2019s difficult to speak and carry on a conversation. You might say three to five words at a time before having to take a breath. Push even harder and you enter the strenuous zone, where \u201cvigorous exercise increases your lactate levels at a point where the body can\u2019t use it all,\u201d he says. In this zone, conversation is pretty much impossible and you\u2019re exerting your full effort. <\/p>\n

So, zones exist, but they\u2019re determined by your blood lactate level rather than your heart rate alone. Your heart rate will correspond to each exercise intensity zone\u2014but you shouldn\u2019t use heart rate to prescribe zones, Dr. Baggish says. <\/p>\n

When it comes to defining heart rate zones, Dr. Gulati is also aligned with the thinking that simpler can be better. Placing your HR in one of only three zones is reasonable because \u201cI don\u2019t think we have as much evidence as people think we do for the other zones,\u201d she notes. \u201cI don\u2019t know where the data has come for us to describe five zones.\u201d <\/p>\n

Still, others argue that using five zones is helpful because they provide even more context when thinking about your range of abilities, Dr. Shah points out. While you can cut out some of the zones to make your training more streamlined, as Dr. Baggish would, a five-zone approach could give an athlete more specific guidance on how to categorize workouts. For example, zone 1 could be a recovery workout, zone 2 could be your base training for longer endurance sessions, zone 3 might be your marathon pace, zone 4 would be a 10K pace, and zone five is like a 5K pace.<\/p>\n

\"soundGet In The (Right) Zone <\/p>\n

How useful all of this is for you ultimately depends on your goals. Heart rate zone training isn\u2019t just for elite athletes or professional runners. \u201cAnyone that has purposeful intensity goals for a workout can benefit from heart rate training,\u201d says Dr. Baggish. \u201cIf you\u2019re someone that exercises and prioritizes having hard days versus easy days, then heart rate can be a good tool to allow you to make sure that you\u2019re accomplishing that.\u201d <\/p>\n

This includes runners and triathletes, as well as those who enjoy structured high-intensity interval training (HIIT)<\/a> workouts. Monitoring your HR and\/or effort can help you gauge when you\u2019re in a high- or low-intensity portion of your session, ensuring you\u2019re properly resting during rest periods. HR zone training is also helpful \u201cif you\u2019re trying to measure performance and fitness and see improvements and then also adjust your training based on how your fitness improves,\u201d Dr. Shah adds. (Your heart rate might decrease as you train, for instance.)<\/p>\n

There\u2019s no need to overanalyze your heart rate data. \u2014Dr. Shah<\/p>\n

However, if you\u2019re a regular gymgoer focused on strength training, or a group fitness class fanatic who\u2019s just there for a good sweat and vibe, you might not need to follow heart rate zone training unless there\u2019s a strong cardio component to your workouts, Dr. Baggish says. The same goes for casual runners and walkers, Dr. Shah says: There\u2019s no need to overanalyze your heart rate data. <\/p>\n

Dr. Gulati emphasizes that HR zones can be valuable when you\u2019re examining them in relation to a clear goal, such as building endurance or doing a high-intensity event (think: an endurance competition like Hyrox<\/a>). She uses them every day with clients during cardiac rehab to determine how much someone with heart disease can exert safely during exercise.<\/p>\n

Using heart rate zone training doesn\u2019t guarantee a better, stronger, or faster performance. But it\u2019s become a nearly universally used training tool for elite athletes, and a helpful one for recreational athletes too. \u201cIf you want to control intensity, you will ultimately have a better shot at getting fitter and probably performing best\u201d by using it, Dr. Baggish says. That said, it\u2019s not the only path to performance success, and there are plenty of elite pro athletes who don\u2019t train with heart rate zones. <\/p>\n

While the math behind HR zones may be flawed\u2014and the breakdown of said zones simpler than many people think\u2014the principles of heart rate zone training and effort-based training are still legit. The key, experts agree, is to use personalized zones that represent your own physiology and abilities, as opposed to zones derived from a generic equation.<\/p>\n

\"heart<\/p>\n

JEAN-YVES LEMOIGNE<\/p>\n

\"audioTracking And Training Takeaways<\/p>\n

Let it be said that you also don\u2019t have to ditch your wearable entirely\u2014but you should reconsider how you use it. That means no more relying on preset zones or calculations if they\u2019re causing confusion for you. <\/p>\n

Dr. Shah recommends using your wearable mainly to track trends (such as whether your heart rate goes down as you continue training). \u201cI wouldn\u2019t obsess over absolute numbers, because they\u2019re not necessarily accurate,\u201d he says. \u201cUse a bit of common sense, and if your body\u2019s feeling good, everything\u2019s getting better, don\u2019t obsess if something on the watch or wearable tells you one thing.\u201d Another note: Chest-strap trackers are typically more accurate than the ones you wear on your wrist.<\/p>\n

Despite current limitations, the future of wearables still looks promising. Eventually, \u201cdevices will become better at learning the individual athlete,\u201d Dr. Baggish predicts. \u201cThey\u2019re starting to integrate your information over time and give you feedback about how you\u2019re progressing.\u201d The algorithms may not be perfect right now, but he hopes they\u2019ll get better. \u201cOnce that happens,\u201d he says, \u201cthere may come a time where the watches can actually determine your thresholds simply by knowing you over the course of two or three months.\u201d <\/p>\n

Dr. Shah also pictures a similar evolution. Imagine you could log a few maximum-effort sprint workouts and your device would automatically calculate personalized zones based on your data. He also hopes these devices will become better able to predict VO2 max<\/a>, using factors like age, sex, heart rate, and speed. <\/p>\n

Maybe one day a watch will know a human body as well as its owner does. But until then, the best gauge of effort may still be the simplest: the rhythm of your breath and the feel of each stride\u2014training cues that no equation, questionable or not, can fully capture. <\/p>\n

\"color Figure Out Your Numbers <\/p>\n

To truly understand your own training zones, you have to measure them yourself rather than rely on a formula, says Dr. Baggish. While heart rate zone training relies on specific numbers tied solely to heart rate, effort-based training more broadly centers on how your body feels, also using cues like breathing, pace, and perceived exertion to guide intensity. Ultimately, whichever style you prefer is up to you. Here\u2019s how to tap into your body\u2019s clues.<\/p>\n

1. Try a field test. <\/p>\n

The Cooper test has you run as far as you possibly can in 12 minutes as an estimate of your VO2 max. Dr. Baggish recommends performing the test once to get your body acquainted with it, then giving yourself a week to recover and trying it again for a more accurate speed assessment. Similarly, if you\u2019ve done plenty of running or cycling workouts at an all-out effort, you can take note of your heart rate during that effort and calculate your heart rate zones accordingly, Dr. Shah adds. (Both of these strategies are much more accurate than the equation, experts agree.)<\/p>\n

2. Do a VO2 max test. <\/p>\n

Typically involving a mask and a bout on the treadmill, this test measures your body\u2019s maximum oxygen use during intense exercise. It\u2019s the gold standard for assessing aerobic fitness and can precisely ID your true heart rate zones. These tests are typically done in sports performance labs, universities, or specialized clinics.<\/p>\n

3. Go by feel. <\/p>\n

Multiple experts reiterate that your body is still your best guide. The \u201ctalk test\u201d\u2014based on the three intensity zones that Dr. Baggish outlined\u2014is an easy way to monitor effort. For instance, if you\u2019re doing an endurance session (like a long run during marathon training), you should be able to talk the whole time. But if you\u2019re doing interval training where you\u2019re running faster, for shorter periods, you shouldn\u2019t be able to talk because you\u2019re pushing yourself, Dr. Gulati says. And if your watch says you\u2019re in zone 4 or 5 but you feel strong and could keep running, you\u2019re probably not actually in your true zone 5.<\/p>\n

\"Headshot<\/p>\n

\u00a0Addison Aloian is the associate health & fitness editor at Women\u2019s Health, where she writes and edits across the health, weight loss, and fitness verticals. She\u2019s also a certified personal trainer through the National Academy of Sports Medicine (NASM). In her free time, you can find her lifting weights at the gym, running on the West Side Highway in New York City\u2014she recently completed her first marathon, the 2025 New York City Marathon\u2014and watching (and critiquing!) the latest movies that have garnered Oscars buzz. In addition to Women’s Health, she\u2019s made an appearance on the Oprah Podcast and her work has also appeared in Allure, StyleCaster, L’Officiel USA, V Magazine, VMAN, and more.\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"These days, everyone from the average Susan to the hardcore data-loving wellness enthusiast has the technology to track…\n","protected":false},"author":2,"featured_media":217948,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[37],"tags":[4959,113189,4830,499,103,61,60,1106,113188],"class_list":{"0":"post-217947","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-fitness","8":"tag-content-type-feature","9":"tag-contentid-f480e3c5-5cd9-4be3-a58e-a391964eec07","10":"tag-displaytype-long-form-article","11":"tag-fitness","12":"tag-health","13":"tag-ie","14":"tag-ireland","15":"tag-locale-us","16":"tag-shorttitle-the-heart-rate-zone-formula-is-flawed-for-women"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/217947","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=217947"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/217947\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/217948"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=217947"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=217947"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=217947"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}