Having Trouble Staying in Zone 2? Here’s What Experts Say to Do

Zone 2 running is supposed to be easy. These relaxed, conversational efforts should make up the bulk of a solid training plan, building the aerobic base that supports every mile to come. So why can keeping your effort level there feel so frustratingly hard?For plenty of runners, heart rate climbs out of zone 2 even when their pace feels totally manageable.Sometimes the problem is the numbers: The formula or method you’re using to set your zones may not reflect your body. Other times, it’s less scientific—your brain, and maybe your ego, is nudging you to run just a little faster than you should.To help you troubleshoot your zone 2 runs, we spoke with a sports cardiologist and an endurance coach who uses heart rate training with his athletes. They explain what might be throwing off your effort, how to calculate your zones more accurately, and the best strategies to optimize the easy running that delivers big benefits.Measure Your Max Heart RateTo figure out your heart rate zones, you have to first know your max heart rate.The old, often-quoted formula to find it is to simply subtract your age from 220. But that equation is mostly outdated, especially for runners, says Trevor Connor, exercise physiologist, coach, and CEO of Fast Talk Labs in Boulder, Colorado. “The 220 equation every once in a while gets someone’s heart rate max right, but it’s a gross estimate,” he says. “You can take two people the same age and their heart rate max could vary by 40 beats, particularly in an athletic population.”Other formulas exist and are slightly more nuanced, such as 208 minus 0.7 multiplied by your age. This method can be more accurate, but often not very precise for runners.One reason, Connor says, is because max heart rate tends to decline less with age in longtime endurance athletes. “They can maintain their max heart rate for a long time,” he explains. Plus, formulas don’t take into account factors such as overall fitness level, genetics, and sex.CHECK OUT OUR FULL GUIDE TO FIGURING OUT MAX HEART RATEFor a much more accurate number, look at your heart rate during an especially tough workout or race. “Often when people run a 3K or 5K race, toward the end, they should be hitting their heart rate max,” says Tamanna Singh, MD, clinical cardiologist and codirector of the Sports Cardiology Center at Cleveland Clinic in Ohio. (As long as you’re going at max effort, rather than just running for fun!)The best way to measure your heart rate on your own is with a chest strap or an arm strap during a workout or race, says Singh. However, she notes that smartwatches have gotten much better at recording heart rate than they were even just a few years ago (and research backs that up).To measure heart rate during a workout, Connor suggests doing seven to eight minutes at a zone 2 or 3 effort to warm up. Then do a time trial by running one mile (or just five minutes) starting at threshold pace and increasing that effort until you reach your absolute maximum intensity, like you cannot go any longer. (He also suggests doing this with a partner so you can push each other and really hit an all-out sprint!)Consider Going to a LabIf you want to get precise, the most accurate way to gauge your max heart rate is to have it professionally measured in a lab. Testing will involve exercises with “a slow, graded increase either in pace or in incline on the treadmill,” while you wear EKG sensors on your chest, notes Singh.Along with your max heart rate, the lab should be able to give you other stats like your lactate threshold 1 (LT1, a.k.a., your aerobic threshold, when lactate begins to rise) and lactate threshold 2 (LT2, your anaerobic threshold, when you can no longer maintain a steady state), says Connor.Just make sure to look for a lab that specializes in athletes because those that primarily cater to a sedentary population won’t necessarily provide you with the information you want, Connor explains. “Their tests are often designed more to detect arrhythmia, signs of incompetence, or focus on health outcomes,” says Connor. He suggests you ask athletes and coaches in your area if they can recommend a lab that works with runners.Zero In on Your Correct ZonesWhatever way you break down your training zones, remember that zone 2 should be an easy effort—usually around 3 to 5 on a scale of 1 to 10 rate of perceived exertion (RPE), with 10 being maximum effort, says Connor.For heart rate, many people use the five-zone model that defines zone 2 as 60 to 70 percent of your max heart rate.Another way to determine zones based on heart rate, which both Connor and Singh actually prefer over the normal max heart rate calculation, is called the Karvonen method. This calculation uses your heart rate reserve, which is your max heart rate minus your resting heart rate.After determining your heart rate reserve, you multiply the number by the percentage of the zone you want to hit (60 to 70 percent for zone 2), then add your resting heart rate again. The result is your heart rate range for that zone.While formulas are certainly useful in a pinch, once again, the most reliable way to pinpoint your heart rate zones is using data from a lab test. “You can use percentages, but it’s different for everyone,” says Connor. “For example, a sedentary person, their LT1 or top end of zone 2, is going to be somewhere around 65 percent of their max. But for an elite runner, their LT1 can be upward of 80 percent of their max.”Connor prefers to determine zones based on someone’s LT numbers rather than simply max heart rate, as it’s much more accurate and based on your physiology rather than a generic formula. He then uses a three-zone model based on an athlete’s LT1 and LT2—where zone 1 is heart rates up to LT1, zone 2 is between LT1 and LT2, and zone 3 is above LT2.Take Watch Data With a Grain of SaltAlthough smartwatches or chest or arm straps tend to be pretty reliable in terms of tracking your heart rate, keep in mind that the time they say you spent in each of your zones during a workout isn’t gospel.For instance, if your watch sets your default zone 2 based on 60 to 70 percent of your max heart rate, but you’ve determined that your max heart rate or zone 2 is higher, the numbers might not reflect the effort of your run.If the numbers your watch sets for zone 2 don’t track with what you’ve found your heart rate to typically be during truly easy-effort runs, you can either ignore them or go into your device’s settings and manually enter what numbers are the high and low range for each of your zones.Look at Your Heart Rate TrendsKeep in mind that your heart rate zones fluctuate from day to day, so there’s no reason to freak out if you find you can’t stay in zone 2 for a day or two.“Heart rate trends are more important than the isolated data points from one specific run,” says Singh. “If you’re usually in the 140-to-150 range on easy runs but one week you notice you’re getting up around 160 to 170, you might think about why—whether you’re tired or getting sick, or you’ve had a couple of late nights or have been drinking alcohol more often,” she says. Those extra factors can be the tipping point that makes your heart rate tick up more than usual.Writing in a journal about how your runs go and information about things like your stress, anxiety, hydration, any allergies or illness, etc., can provide insight about what’s affecting your heart rate from run to run.Caveat: Only get this detailed if you want to and find it helpful, says Singh. “You have to ask yourself what kind of a person you are,” she says. “Are you someone who’s going to get caught up in the wheels of all that data? If that’s going to cause you more anxiety or stress or grief, then don’t do it.”Be Honest With Yourself You don’t have to blindly follow the heart rate numbers on your watch. But before you accept that your heart rate is just naturally higher than the zones dictate, make sure you’re not running harder than you think.If every easy run goes above zone 2, try going for a run with a heart rate monitor, but without checking your pace. Focus on tapping into a truly easy effort in which you can hold a full conversation. (No worrying about how slow you’re going!) Then go back and look at the data to see your pace at zone 2. You might be surprised by how much you should slow down.Then, remind yourself it’s okay if your heart rate goes above zone 2 on occasion.“There are so many things that can change your heart rate during a run—your thoughts, your excitement, sometimes even the cadence of a song you’re listening to,” says Singh.Other factors like caffeine, lack of sleep, or mental burnout can also make your heart rate higher. “If you felt a run was easy and you’re being honest with yourself, and the effort was where you want it for that day, then trust that data over the heart rate.”Connor says older or more experienced runners may find their heart rate readily creeping above zone 2 more often because they don’t want to slow down as much as they should. “Masters athletes can really struggle with finding their correct zones and accepting them,” he says. “People need to make sure they’re using realistic numbers. It’s better to err on the side of being a little too easy rather than a little too hard.”FOLLOW THESE TIPS FOR SLOWING DOWN ON EASY DAYS Stop Comparing Yourself to Others“The runner next to you is not you,” says Singh. “We get so influenced by what other people are doing, and it’s easy to think, their zone 2 is 130, so my zone 2 should be 130. But you’re your own person, you’re your own runner. Embrace that and be open to learning more about your running style, your body, how it responds to different stressors and rises up to certain challenges. Once you do that, you can start to see your potential.”At the end of the day, cut yourself some slack and try not to overthink your zone on every single run, says Singh. “If you really try to be a stickler about the percentage range of your zones, it will get frustrating and suddenly you’re just running to hit a zone rather than an effort,” she continues. “The downside to that is you might be limiting your potential or you might be working harder than you should.”Laurel Leicht is a writer and editor in Brooklyn. She's covered health, fitness, and travel for outlets including Well+Good, Glamour, and O, The Oprah Magazine.