Fitness: Does high blood pressure limit your exercise options?

Exercise has long been associated with heart health. Walk, run, swim, bike or lift on a regular basis and your risk of heart disease and stroke decreases dramatically. The rewards are almost instantaneous with a drop in blood pressure notable when you swap out time on the couch for time in the gym. That’s good news for anyone with high blood pressure, which increases the chances of adverse cardiac events.

The Heart and Stroke Foundation of Canada says about one in four Canadians have been diagnosed with hypertension. That number increases in an older demographic to 51 per cent in Canadians 60-79 years of age. 

In most cases, exercise is considered safe for anyone who is effectively managing their blood pressure through medication or changes to their lifestyle. But it’s common for health-care professionals, including many organizations like the European Society of Hypertension, American College of Cardiology and the International Society of Hypertension, to advise keeping intensity in the moderate range to avoid the added cardiac stress associated with high intensity aerobic exercise. But the science related to the risk of hypertension and physical activity was largely informed by self-reported data that, when it comes to exercise, is unreliable. Not only do people routinely fudge how often they exercise, when it comes to intensity of effort there is little uniformity in determining whether a workout is light, moderate or vigorous. 

With the growing number of studies using wearable devices to accurately track activity over the course of a full day, an increasing number of exercise recommendations are being scrutinized based on more reliable data. To find out more about the relationship between exercise intensity and hypertension, a team of Australian researchers analyzed a large cohort of adults with high blood pressure who wore an accelerometer to track their daily activity.

“Using wearables-based data, our study is among the first to investigate the potential role of cardiovascular stress-related physical activity properties (intensity and bout length) on major adverse cardiovascular events in adults with diagnosed hypertension,” the researchers said. 

The researchers arranged 38,960 U.K. residents with hypertension into groups based on exercise intensity and duration. Short bouts of exercise were defined as up to three minutes at a moderate intensity and no longer than one minute at high intensity. Long bouts were any workout over five minutes of moderate intensity and over two minutes of high-intensity exercise. Hospitalization records of the cohort were then cross referenced over an eight-year period highlighting any documentation of a stroke, heart attack or heart failure.

The results offer new insight into how different types of exercise affect the heart health of people with high blood pressure. 

The good news is short bouts (up to 60 seconds) of high-intensity exercise proved not only safe, but also offer a protective effect, with fewer cardiac events found in study participants who exercised using multiple short bouts of high-intensity exercise. But the same can’t be said for high-intensity exercise lasting more than 10 minutes. 

“Such prolonged bouts could induce adverse vascular stress and adrenal gland dysfunction, which subsequently contribute to dysregulated cardiovascular function and induce increased arterial pressure,” the researchers said. “This can damage arterial walls, leading to increased stroke incidence.”

That doesn’t mean everyone with hypertension needs to avoid longer workouts done at a higher intensity. But if it’s a struggle keeping your blood pressure in a safe range and you want to start training for a speedy 5K, you may want to consult with your physician and/or cardiologist. 

“The cardioprotective effects of physical activity in hypertension depend not only intensity, but also on the duration of the physical activity bouts,” the researchers said. 

On the flip side, if you love doing multiple short bouts of high-intensity intervals in the pool, gym or on your bike, your heart is not only likely up to the challenge, but will also benefit from being put through its paces. 

How do you know whether your workout is high or moderate intensity? Take the cue from the research team and start relying on wearables to track your exercise stats. Exercise intensity is based on heart rate response during exercise while factoring in your maximum heart rate, which is based on age, both of which can be tracked on most smart watches. 

And since smart watches keep all the historical data from your workouts you can share your heart rate’s response to exercise with your medical team and discuss the most prudent form of exercise. Cardiac events while exercising are rare, but the accumulation of stress on the heart can lead to complications down the road. The best option is to find an exercise format that improves heart health in the long and short term as well as meeting the rest of your health and fitness goals. 

“Our findings, alongside recent device-based studies focused on short bouts of high intensity activities, provide valuable insights for potentially re-evaluating treatment options for patients with hypertension,” the researchers said.