By Tom Ward

Copyright gq

Whoever we are, whatever we’re doing, we have a measurable heart rate. It’s a pretty clear sign of being alive. But what should your heart rate be when exercising?
When we exercise, our heart rate speeds up as it pumps blood around the body. This process moves oxygen and other such useful substances to our muscles. That oxygen is used to power us working out. If we’re ‘fit,’ our hearts can do this efficiently, and need to beat less times per minute. If we’re unfit, our hearts will need to beat harder. This is a sliding scale: a seasoned marathon runner is used to moving at a relatively steady, fairly slow pace, so even though they’re fit, their heart rate may still skyrocket if they jump on the battle ropes.
Understanding your heart rate (HR) and what it should be at certain points is key for keeping you on track, and out of the danger zone. Here’s what you need to know.
What’s the basic concept?
Measuring your HR helps ensure you’re training at the right intensity for your goals. It can also prevent overtraining, fatigue, or unnecessary stress on the heart. “While your heart rate should be relatively low during sleep or relaxation, it is completely normal for it to rise—sometimes even significantly—during exercise or stressful periods,” explains Alina Cox, expert trainer at ClubQ Health.
“A healthy resting heart rate (RHR) varies, but the general ranges are between 60-100 [beats per minute] for the average person, and 40-50 bpm for well-trained individuals,” adds personal trainer Adam Enaz. Typically when we talk about heart rate, as well as RHR we talk about max heart rate, MHR.
Often, you’ll have a pretty good idea of how your heart is coping because you’ll be able to feel it hammering in your chest. For an accurate reading, you might invest in a wearable heart rate monitor. Smart watches have all the techno wizardry required, as do those chest straps that bare-chested male runners seem to love. We’d advise the former.
Why is knowing your HR important?
Your heart rate can teach you important information about your general health status. According to research, a consistently elevated resting heart rate is a sign of poor physical fitness, and heightened blood pressure. And, as per Harvard Health: “a resting heart rate near the top of the 60 to 100 range can increase your risk for cardiovascular disease and even early death.”
“Besides tracking my heart rate for fitness purposes, I have found it incredibly useful for monitoring things like stress levels or even early signs of illness,” adds Cox. “For example, last week I noticed that my heart rate was consistently higher than usual at rest, and I knew my body was likely fighting something. Not even 12 hours later, I was in bed with a cold.”
With smartwatches making it easier than ever to track, it is a quick and simple way to really tune into how your body is feeling.
What if you’re outside of these thresholds?
First of all, panicking about anything is only going to raise your HR, so don’t do that. But, it is worth noting what your RHR and MHR are as a heart rate that is too high or too low can indicate inefficiency in cardiovascular function, or poor recovery.
According to Cox, the risks of too high a heart rate are overtraining, injury, fatigue and high levels of stress hormones. “Consistently training at 90%+ MHR can lead to problems, and if your HR stays elevated for a long time after exercise, it could indicate poor recovery or dehydration,” she says.
On the flip side, a very low resting HR (<40 bpm in non-athletes) could signal bradycardia—a medical condition in which the heart cannot pump enough blood, and which may cause dizziness or fatigue. “If your HR doesn’t increase properly during exercise, it might indicate a low fitness level, or a need for more aerobic conditioning,” says Cox. If you’re still having issues with low RHR, consult a GP, as bradycardia can be serious. Optimal HR for general fitness Cox and Enaz agree that it’s best to train within 50-85% of your max heart rate, depending on your goal. That said, there are certain athletes who excel even with abnormal heart rates. Some elite endurance athletes like Tour de France cyclists have resting HRs as low as 30-40 bpm due to extreme cardiovascular efficiency. Meanwhile, athletes often train with high-intensity heart rate fluctuations, but despite this, many of them have learned to stay calm in the ring, keeping their HR lower than expected. Freediver Stig Pryds, for example, experiences a drop to 37 BPM while diving. All of the above depends on training adaptation, genetics, and sport-specific demands, though, so don’t feel bad about yourself if you’re not quite hitting these numbers on your cycles, sparring sessions, or free diving attempts. What should your heart rate be when exercising harder? Given that we’re all different, there will always be outliers and exceptions to the rule, but generally your heart rate stays in the fat-burning zone during weight training and steady-state cardio, falling between 50 and 70 percent of your maximal heart rate. This happens because fat is a more efficient fuel source at lower intensities, enabling you to sustain those activities for longer. As the intensity increases and your heart rate rises, your body switches to using alternative fuel sources. Because they supply the fastest energy, your body mostly burns carbs during vigorous HIIT workouts or sprints. During moderate or high-rep exercise, when your heart rate is between 70 and 80% of its maximum, your body uses a combination of fat and carbs for fuel. As for optimal HR zones per exercise, Enaz breaks it down like this: Walking/Light Cycling – 50-60% MHR Steady-State Running – 60-75% MHR Weightlifting – 60-80% MHR HIIT/Sprints – 80-95% If your numbers are tracking higher or lower than above, note that. If it stays consistent for a few sessions, it may be worth speaking to a PT about mixing up your approach. How to work on your heart rate Several studies have proven that regular exercise is an effective way to lower our resting heart rates over time. Researchers found that regular exercise strengthens the heart, helping it pump more blood with each beat, thereby requiring fewer beats per minute to maintain a solid blood flow. Another study found that Exercise can help the parasympathetic nervous system, reducing stress to slow our RHR. Endurance exercise, like swimming, running, cycling and rowing are thought to be particularly adept at lowering RHR, while even brief blasts of intense workouts like HIIT can have a significant impact. “To track your progress, check your current average resting heart rate, then revisit it a few weeks or months later,” Cox says. “If you have kept up your fitness routine, you should notice a decrease in your heart rate as your fitness improves.” If you want to actively lower your heart rate while exercising, leading to more efficient performance, Cox recommends deep, diaphragmatic breathing to help calm the body. The key is to inhale through your nose and exhale through your mouth. “A good warm-up is also essential,” she says. “Before starting a more intense activity, a warm-up allows your cardiovascular system to acclimatize by gradually increasing your heart rate and blood flow.” Your nutrition can also affect your heart rate during exercise. Eating glucose-rich foods like whole grains or fruits about three hours before working out can help keep your heart rate lower, as your body can use the energy more efficiently. Enaz also recommends: Nasal Breathing “Breathing through your nose instead of your mouth improves oxygen efficiency and keeps HR lower.” Hydration & Electrolytes “Dehydration makes HR higher at any given intensity. Drinking enough water and replenishing electrolytes helps control it.” Getting Enough Sleep “Poor sleep raises resting heart rate and makes workouts feel harder. Prioritizing 7-9 hours improves HR recovery.”Getting Enough Sleep