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Go until it feels tough. Hush harder. One more rep. If you’ve ever taken a group fitness class, worked with a trainer, or followed a workout app, you’ve heard these phrases over and over again. But here’s my question. What does tough actually mean? How hard is hard? How do you know when a set is heavy enough to give you results, but not so heavy that you’re setting yourself up for an injury or burnout? Welcome back to the 925 Wellness Podcast, the podcast where your career growth meets your health. I’m your host, Aisha Tahir, a clinical exercise physiologist and a corporate wellness consultant. Today we’re talking about how to train SMAT with your intensity level. You’re like, huh, what are intensity levels? In exercise physiology world, we talk about intensity in terms of RPE, I’m sure you have heard this term, and heart rate zones. Every effective exercise plan comes down to three dials frequency, duration, and intensity. Most of us have the first two figured out. You would agree, right? You know how many days a week you work out and how long each session lasts. So that’s duration. Now, intensity is the dial that most people guess on. And I’ve been getting so many Instagram DMs that I was like, I have to talk about this on the podcast. Why? Because it matters. Because it tells you whether you’re working too hard or not hard enough. For busy professionals, that’s a big deal. When your time is limited, you want every workout to count. And when your work stress is high, you don’t want your training to pile on more stress on your body than you can recover from, right? And that has been happening to me lately. I’ve been so busy trying to just get my work done at the practice and then record the episodes. And I’m trying to get ready for a couple of big speeches. And I’m like, oh my gosh, I don’t want to push so hard that I get injured. So I completely understand where you come from. Now there are three common ways to measure intensity. Today we’ll talk about all three of them. You’ll learn about RPE and heart rate zones and the talk test. That is the third one, which is kind of like a built-in test within our bodies. And by the end of this episode, you’ll know how to use RPE and heart rate zones together. And you’ll also know what it means to use the talk test, right? Okay, let’s get into it. RPE. RPE stands for rate or rating of perceived exertion. Simply put, it’s a way to score how hard an exercise feels to you. Perceived exertion is how hard you feel your body is working based on the physical sensations you notice during exercise. Your heart beats faster, your breathing gets faster and deeper, you start to sweat, muscles begin to fatigue. That is perceived exertion, right? RPE takes all of those signals and turns them into a number. So you can rate it. That’s why it’s called rate of perceived exertion. It’s almost like a scale. Okay, I’m gonna get into that right away. Now you might be thinking, Aisha, that sounds pretty subjective. And you’re right. That is, it’s actually this scale’s strength. Let me explain why the feel matters and the science behind it. Then we will get into the scale part. Picture two people who are equally strong. Both can deadlift 200 pounds on the barbell. Their coach tells them both to lift 70% of their max, which would be in this case, 140 pounds. On paper, that’s the same workout. But for one of them, 140 pounds might be so easy. They can probably get in 10 reps. Whereas the other person, they’re like, oh, 140 pounds today? It feels like a grind. I can probably only get two reps in. And it’s the same for a 5k race for two athletes. Why? Because your body doesn’t just respond to the weight on the bar. Your central nervous system, right here, right? And your muscles, they’re always in communication with each other. And they respond to the total stress in your life. Sleep, emotional stress, nutrition, recovery from your last workout session. Even whether your strength leans more towards endurance or power, that also comes into play. And that’s a topic for another podcast episode. And I promise I’ll get back to it and get into it in a future episode. But right now, let’s just pin it. It does come into play, though. All that changes how a weight feels on a given day or how a workout feels for you on a given day. Now, RPE gives you a real-time snapshot of all those variables. And this gets more important as the intensity goes up. The heavier you lift, the more sensitive you become to things outside the gym. So think about that big product launch you have coming for your work or the year-end crunch. You’re sleeping five hours a night, and you’re like, I need to get those sales in, I need to get those spreadsheets up for my company. That is gonna come into play in your rate of perceived exertion and how you are feeling the next day. So your programming might say that you have to work out at 80% of your max intensity, but that 80% might feel like 100% to you that next day, right? So you might have to dial it down. RPE tells you what that 80% actually costs you that day. Now let’s talk about the scale itself. The original RPE scale was created by a Swedish researcher. His name was Gunnar Borg. It runs from 6 to 20. 6 means no exertion at all, sitting or standing still, like we mostly do while we are working at our desktop, right? 20 means maximal exertion, as if you were doing a 100-meter sprint. Now, here is how it maps out. 6, no exertion. 9, very light, an easy-paced walk, I would say. 10 to 14, somewhat hard, which is what we call a moderate intensity workout, like an easy jog. 15 or above is very hard to maximal. So that’s vigorous intensity, like running for most people, or you’re doing laps in a pool. Or if you’re on your bike, you’re going uphill. Now, here’s the clever part of this scale because a lot of times I know a lot of people ask me, like, why is it starting at six? And here’s the reason why, which I found out very recently too, that Borg designed this scale to roughly track heart rate in healthy adults. Now, think about it. Multiply six by 10, what does it give you? It is 60 beats per minute. So that means if you’re at rest, mostly your heart rate is around 60 beats per minute for a healthy adult. If you are at an RPE of 12 on Borg scale, like you’re working at a moderately easy pace, that’s roughly 120 beats per minute. One caveat though, from yours truly, an exercise physiologist. This is just an estimate. And I think you can probably tell already, right? It’s not a measurement. It was built around the average healthy adult. Your age and your fitness levels change, your heart rate response as you grow older or as you get more fit. So check what your own numbers look like. They might look very different than what I’m talking about. Now you might be thinking, how will I remember all of these numbers from 6 to 20? Because while I’m working out, it’s hard enough to remember my own name. I understand. I know I’ve been there too. I have an easier version for you because I think when Borg started, you know, proposing this scale, he realized that it’s very hard for people to remember the scale from 6 to 20. And he actually revised the scale and he revised it to a modified version, which is from 0 to 10. 0 is when you’re at rest, not doing anything much, just sitting down, watching TV. And 10 is when you’re going at an all-out effort. That is the RPE scale that you can follow. Now, you’re like, okay, that’s all well and good. The scale is now simpler from zero to 10, and I know how to apply it to a cardio activity. But I don’t know how it’s applicable to weightlifting or strength training. I have a treat for you over here because I’m gonna give you a cheat sheet for understanding your rate of perceived exertion when you are lifting weights. Okay, RPE for strength training, how I like to measure it and how we physiologists measure it, is called reps in reserve. Now, if you lift weights, there is a version of RPE built just for you. And the reason we use reps in reserve instead of RPE is because it gives you a good idea of how much work is left, like how much work you could have done without getting fatigued. So instead of asking, how hard did that particular lift feel for you? Like let’s say you’re uh doing a bench press and you did three reps and now you’re like, I don’t know what my RPE is. You can ask yourself, how many more reps could I have done and gotten to that very, very fatigued level? So here’s how it goes. RPE 10 would be zero reps left in reserve. You gave everything. RPE 9, one more rep is left in your tank. RPE of eight, two more reps in the tank. RPE of seven, three more reps in the tank. I think you get the idea, right? Here’s the example. Say you are bench pressing 100 pounds for eight reps. If you finish and you feel like you could squeeze out exactly one more rep, that’s about a perceived exertion of nine. If the same weight feels like you’ve got two more left in you, that’s closer to a perceived exertion of eight. Now, my pro tip here for you is rate your last working set. If you’re doing five sets of bicep curls, give set five a number. Do that every session, and you’ll have a consistent way to track your training and you will know what that perceived exertion looks like at any given day for you for that exercise. Okay. You’re like, why do I need to bother with all of this? Here is what RPE gives you that a percentage on a spreadsheet can’t. It adjusts for daily variability, bad sleep, stressful meeting, a long travel day. RPE accounts for all of that. It encourages smart progression and you can add load when the work feels easier in your life. Okay. Third, it helps you build self-awareness. You learn to read your body’s signals. It also helps you communicate with your coach if you have a coach who’s who you’re working with. Because the coach might think, oh, I’ve seen you lift heavier or I’ve seen you run faster. This must feel like an eight for you. And you’re like, no way, coach, not today. I I couldn’t sleep last night, right? So that’s a more subjective way to uh quantify your exertion level to your coach as well. And it works when the heart rate monitor doesn’t work. So if you don’t have heart rate monitor with you, and or a lot of my patients are on medications that affect heart rate, like the beta blockers. They would lower your heart rate over time. And that means that your heart rate is not giving you the real picture of what’s happening within your body. It’s a modified heart rate now because of the medication. RPE gives you a reliable way to understand how hard you’re working in that situation. And finally, of course, this is something that you all we all know, and I guess you know it already, that you don’t need any equipment, no watch, no chest trap. It’s just you. You can tell how hard you’re working. And you know, it is a number based on your subjective perceived exertion. Now, I just talked to you about how hard the exercise feels. Now, let’s talk about how hard your heart is actually working, because it is the second side of that equation. You can tell your perceived exertion based off of the work you’re doing and what is going on in your life. You can also tell about how hard you’re working with how fast you can talk or how slow you can talk, or if you can’t talk at all, which was the talk test. And I do want to touch upon that before we go into your heart rate. Why? Because all three of these tools work together in conjunction and they give you the best result if you are using them all together. So for the talk test, if you’re at rest, like I’m sitting down right now and talking to you, you can see how I can talk very fast if you if I wanted to, or I can go at my own pace. But if I started, if I stood up and did four or five jumping jacks in front of you, I would start getting breathier, so I would have to speak slowly, right? So that would give you an idea. Okay, I can still talk in sentences, but now my speech is getting choppier. That means that you are at an aerobic pace or aerobic intensity. If I was to start jogging here and I came back after a 20-second jog, now I’ll be even breath here. And I might be able to say sentences, you might not be able to understand me at all. Guess what? Now you are at a moderately vigorous activity or intensity level. And finally, if I was to go out on a 200-meter dash and come back and sit in front of the microphone, guess what? I can’t talk. I won’t be able to talk. I’ll be huffing and puffing, and I’ll be like, I have to catch my breath before I can start recording again, right? So that is an RPE of eight or higher, or a very vigorous exertion level. So you can tell all of those exertion levels, or you can rate your perceived exertion based off of how well you can talk, or if you can speak in full sentences or not. Okay, let’s get back to those heart rate zones because I do want to explain what heart rate zones are and how heart rate zones help us understand perceived exertion levels too. Training in target heart rate zones helps keep your workouts safe and effective, just like RPE does. When you know how hard you need to work, you can reach your goals without pushing your body further than it needs to go. Step number one, you need to find your maximum heart rate if you want to know your heart rate zones. Everything starts with your maximum heart rate or MHR for short. You might have seen that all over TikTok. That’s roughly the fastest your heart can beat. It varies from person to person, but age is the usual starting point for an estimate. The classic formula is simple: 220 minus your age. If you’re 40 years old, your estimated max is 180 beats per minute. There’s also a Tanaka formula, which researchers consider it is a bit more accurate across age groups, which is multiply your age by 0.7 and then subtract it from the number 208. For a 40-year-old, that is 208 minus 28, which also leads to a maximum heart rate of 180. These formulas are estimates only, and real people can land 10 or more beats above or below their actual maximum heart rate. For knowing or understanding your individualized real maximum heart rate number, you would have to do a Bruce protocol stress test. And if you need more information on where to get one in New York City, you can reach out to me. Again, that is my wheelhouse, so I can help you with that. That being said, if you’re just using the formulas, just remember that these are estimates. Some can be higher, some can be lower, but it’s a good estimate to work off of. Once you have your maximum heart rate number, now you can calculate your five heart rate zones. We break our heart rate training zones into five zones. Each one is a percentage of your max heart rate, and each one feels different and does something different for your body. Zone one, very light, which is under 57% of your max heart rate. This is gentle activity. Talking is no problem at all. You won’t burn as many calories as you would in higher zones, but this zone is perfect for recovery. So if you take a recovery day, this is what you want to do. Think of easy cycling on flat ground. Maybe you get that city bike out and just go around on West Side Highway. Maybe it’s like pedaling under the desk. A lot of my um patients have now uh under the desk bikes. So that would be a good example of that too. Or maybe it’s just an evening stroll in Central Park. Zone two, light. It’s still light activity, 57 to 63% of your max heart rate. This is easy and comfortable. You can hold a full conversation. Um, though you might be breathing a little bit heavier. Think of it as like a power walking or a little bit like of a light jog, depending on where you are in your fitness level. Um, it won’t give you the biggest cardio gains, but studies show that training in this zone helps you lower body fat, blood pressure, and cholesterol. At this intensity, your body leans more on fat for fuel. Zone three, moderate, 64 to 76% of your max. Now you’re breathing harder. You can still speak in short sentences, you can burn more calories per minute than in the light zone because you’re working harder. A brisk walk or an easy run would be a good example. Zone 4 is vigorous, 77 to 95% of your max. Now you’re breathing hard. This is your tempo run level of activity, or you’re really pushing hard if you’re lifting weights. So this is where you would be. And your last zone is zone five. Maximal, 96 to 100% of your max heart rate. This is all out. You can’t go any higher. And most people can’t stay here for more than a few minutes. Probably one to two minutes. That’s it. You’ll only manage single words between gasps. Use this zone for short bursts and interval training. Go hard about for a minute, drop to an easier pace for a few minutes, and then repeat. Okay. This is also where your body uses most of the carbohydrate stores within the cells. So this is where carbohydrates are being used as fuel. I have a full table with all these heart rate zones and what they mean for your training linked in the show notes. So you can click on it and download that chart. A note on fat burning zones, because it is something that has been coming up in my DMs, and I want to clear up this myth before we move on. You’ll hear that lower zones are the fat-burning zone. It’s true that a bigger share of your fuel comes from fat at lower intensities, but higher intensity burns more calories per minute, which also means more fat per minute. Both have a place. The best plan for your body composition is the one you can do consistently. And quite honestly, you need a little bit of both. A little bit of low intensity training where you’re just burning fat, and a little bit of high-intensity training where you’re mostly burning your carbohydrates as fuel. So putting it all together, here it is. So which one should you use? You’re like, okay, should I use RPE? Should I use heart rate zones? My answer is both. They check each other out. Heart rate gives you an objective number. RPE tells you that number, how it feels on a given day for you. When they line up, you’re on track. And when they don’t, that’s information for you. That means that you can build up on that information. Maybe you can share that information with your physician andor your exercise physiologist. That is all for today as far as RPE and heart rate zones are concerned. Before we wrap it up, I do have a disclaimer to share. This episode is for education and it’s not a medical advice. If you have a heart condition or take medications that affect your heart, talk to your doctor before changing your training. If this episode helped you, share it with a coworker who’s always saying, push harder. Follow 9 to 5 Wellness wherever you listen to your podcast. New episodes drop every Friday and Sunday. And if your brand wants to partner with the show, visit 925Wellness.comslash brand partnerships. Until next time, train smart and I’ll see you. Bye.