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Knowing When to Slow Down: Catching Irregular Heartbeats during Exercise

We’ve all been there … the last few steps away from the finish line, the last mile on the exercise bike, the countdown to the end of a great bench press session. You can feel your blood pounding in your ears, the adrenaline rushing through your veins, your racing heartbeat… until it literally skips a beat. And not in a good way. 

Knowing When to Slow Down: Catching Irregular Heartbeats during Exercise


The first instinct is to slow down. What if we pushed ourselves too much? Better to be safe than sorry. The news of sudden cardiac deaths in seemingly healthy people, many of them young, who collapsed right in the middle of their workouts, has made everyone a little nervous. These events have us asking some tough questions - how much is too much? Can you hurt your heart by exercising too much? 

Does too much exercise cause heart problems? 

Sudden cardiac deaths account for 40–50% of all heart-related deaths and 15–20% of overall mortality. Studies show that men who are not used to intensive exercise are most at risk, while women and regular exercisers have slightly reduced risks. While it seems like the chances of a heart attack during exercise are higher if you suddenly go from couch potato to 5K, cases where high-intensity exercises lead to heart rhythm abnormalities, are the ones we should keep a lookout for. 

What happens inside our bodies as we exercise?

Just like any other muscle in your body, as you begin to exercise, your heart will quickly contract and relax and blood circulation will increase. This helps to get oxygen-rich blood to your muscles, faster. As you continue to pick up the pace, the demand for oxygen in the blood will increase. The heart will try and keep up with this demand by increasing the heart rate as well as the force with which the heart muscle contracts. This is why the heart races and body temperature rises as you move your muscles. 

That Funny Feeling: What symptoms of heart disease could you experience while exercising? 

If the exercise puts too much strain on your heart, you may experience: 

  • Dizziness or lightheadedness
  • Chest pain
  • Shortness of breath
  • Nausea
  • Irregular heartbeat or pulse

It is important that you pay attention to these warning signs, and rest. The most alarming symptom for most people is the uncomfortable sensation of irregular heartbeats or arrhythmias. 

Atrial fibrillation is a type of arrhythmia that commonly occurs in older adults with coronary artery disease, valvular disease, or other heart diseases. Studies have shown that they also occur in people who take part in regular endurance exercise. One study estimated that the risk of atrial fibrillation increased by about 16%, and the risk of atrial flutter increased by 42%,  for every 10 years of regular endurance exercise, i.e. if one exercised three or more times per week, for over 30 minutes. 

Tennis icon Billie Jean King and basketball star Larry Bird are prominent examples of star athletes who developed atrial fibrillation when they were still young and active. 

The Panic Button: Can too much exercise harm my heart? 

The most common recommendation for people who experience arrhythmias while exercising would be to scale down the duration and intensity of the exercise, but athletes in training or those who work consistently towards their fitness goals are often reluctant to give up on their hard-won stamina. 

Although a European study showed that male athletes reported fewer episodes of arrhythmia after reducing their athletic activity; the response was greater in younger athletes (30% reduction in episodes) than in older athletes (11% reduction in episodes).

The Next Step: Running for a Stress Test 

Experiencing atrial fibrillations or heart flutters can be scary, and might prompt you to reschedule your yearly health check-up. A full examination may reveal a stable resting heart rate, normal blood pressure, and no findings on an ECG. The logical next step is to find out if the arrhythmia is stress-induced. Enter the treadmill test! 

During a stress test, you walk on a treadmill so that you force your heart to work harder, while you step up your activity levels and monitor its performance using an ECG and blood pressure graphs. Doctors would look out for symptoms like shortness of breath, chest pain, excessive sweating and fatigue as well. These changes could point towards coronary artery disease (CAD)  or exercise induced arrhythmias like atrial fibrillation or tachyarrhythmias (both supraventricular and ventricular)

But there is a downside. 

A stress test may not be able to pick up a developing heart condition or an underlying arrhythmia effectively. The test lasts only 15-20 minutes, giving the doctors only a limited estimate of your heart condition. Exercising in an examination room can never replicate the environmental conditions you are otherwise exposed to when taking part in endurance exercises, in your routine life. That’s why a stress test does fall short when compared to continuous monitoring of both heart rate and heart rhythm, especially during exercise.

Active Monitoring: The Smart Approach 

Wearable heart rate monitors have become more popular lately. How can a heart rate monitor be beneficial to your workouts? It can definitely measure heart rates effectively, so you know when you’re getting the most out of your exercise regimen. You can watch out for alarming increases and slow down when you need to. But there are limitations here as well, because devices that pick up fluctuations in heart rate may not be able to pick up changes in heart rhythm. 

Just like everything in life, balance is the key. While working on your exercise routine, it does make sense to establish your baseline heart rate, endurance and stamina before rushing into an intense workout. As a seasoned athlete or as someone who loves their daily endorphin rush after a great workout,  monitoring your heart rate and ECG while exercising is a great way to detect fluctuations. 

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