Should you maintain an elevated heart rate for a long time?

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We often refer to our heart rate when evaluating our performance while working out. The common thought goes; “if, while exercising, you can maintain a high heart rate for a while, you are getting a good workout”. We’ve been conditioned to believe that the longer or harder we push ourselves, the healthier we will become.

Did you know that endurance activities like marathon running can have adverse effects on your health? Besides Yale University’s shocking study that ‘82 percent of marathoners suffer from a condition known as “stage 1 acute kidney injury” (Fetters, 2017), long duration running activities can increase oxidative stress, which then leads to a build-up of CAC plaque within the arteries. It seems that working out to a high heart rate for a long time isn’t necessarily something you want. 

Typically, with traditional exercise methods, we must work out for a long period of time to see results. But studies show that, if done correctly, one can achieve the same results often associated with long form exercise in just a few minutes intense sprint interval training. In fact, research shows that interval training can prevent heart-related issues (Suryanegara, 2019).

There are five heart rate zones to measure cardiovascular intensity during physical activity. Zone 1 measures the max heart rate intensity during very light physical activity while Zone 5 measures the highest max heart rate percentage you can possibly reach safely: maximum intensity.

When you exercise at intensities greater than 70 percent of your max heart rate, your body uses carbohydrates as the primary source of fuel (Lewis, 2019). In CAR.O.L’s case, that fuel is glycogen. Reaching between 80 to 90 percent of your max heart rate during interval exercise is an ideal range for depleting glycogen (sugar stores), but steadily holding or even surpassing your max heart rate for a longer period of time than recommended can go from dangerous to detrimental. This can happen during long duration cardio such as intense cycling classes.

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For the average person performing interval exercise, you hold your max heart rate for only a few seconds (Lapidos, 2019) followed by a recovery period after each interval. Holding an accelerated heart rate for minutes at a time without recovery periods in between is way too long. High intensity exercise continued over hours and repeated regularly over years and decades “stretches” the heart, disrupting muscle fibres and causing micro-tears that do permanent damage (Laurance, 2012).

In rare cases, raising your heart rate above your max heart rate level can result in heart palpitations due to overtraining of your heart. A build-up of plaque called ‘coronary artery calcium’ (CAC) can eventually lead to long-term-damage including heart disease, stroke and heart attack. "High levels of exercise over time may cause stress on the arteries leading to higher CAC," said Dr Jamal Rana of the American College of Cardiology in a press release.

Because you hit your peak heart rate for only a few seconds followed by a recovery period during your ride, CAR.O.L eliminates the need for holding your maximum heart rate for an extended period of time. CAR.O.L’s interval training method can prevent micro-tears, while preventing cardiovascular blood vessel inflammation caused be plaque and calcium build-up.

Performing two 20-second sprints on CAR.O.L up to 4 times a week is not only one of the safest way to practice interval exercise, but it has proven that doing more cardio than needed is not equivalent to better fitness or health results.




Referenced Sources in this Post:

Suryanegara J. (2019) ‘High intensity interval training protects the heart during increased metabolic demand in patients with type 2 diabetes: a randomised controlled trial’. Acta Diabetol. Assessed: 06 March 2019.

Chertoff J. and Bell A. (2020) ‘Why Do Athletes Have a Lower Resting Heart Rate?’ Healthline Magazine. 21 April 2020.

Rana, J. (2017) ‘Physically active white men at high risk for plaque buildup in arteries’. American College of Cardiology.Assessed: 16 October.

Laurance, J. (2012) Marathon Running Is Bad For You, and it's Best to Keep Exercise to a Maximum of 50 Minutes a Day Say Doctors’. The Independent UK. Available at: (Assessed: 29 November 20121).

Lapidos, R. (2019) ‘Exactly How Many Seconds to Maintain Your Max Heart Rate for in a HIIT Workout, According to Trainers’. Well + Good. Available at: (Assessed: 16 November 2019).