Zone 2 Fitness: The Key to Cardiovascular Health

Image: Optimise

“Train slow to run fast”

As studied by Howard J Luks, MD, the key to health and longevity may just be to slow down, believe it or not. Whether that’s running, cycling, swimming or rowing, the best way to improve performance, minimise injuries and thus longevity is sticking to zone 2 fitness.

Finding your zone 2:

Zone 2 running and general fitness is, to put it simply, “taking it easy” during cardio. For example, while running in your zone 2 heart rate zone, you should be able to talk and breathe through your nose.

To find your zone 2 heart rate, you should be somewhere between 65-75% of your maximum heart rate. Estimates of your min and max HR can be found on websites such as: omnicalculator.com and myprocoach.net.  To find your accurate zone 2, you first need to find your resting and maximum heart rate using a heart rate tracker, such as a wearable like a Whoop, a smart watch, or a chest strap. However, if you’re budget restricted, you can find a crude estimate of your maximum heart rate by using the old method of subtracting your age from 220.

Heart rate zones shown in percentages.

The benefits of zone 2:

Exercising in zone 2 not only increases your fitness and injury risk, it has a huge effect on your mitochondria, according to Luks. There are three issues surrounding the mitochondria which are addressed by zone 2 fitness, these are: The number of mitochondria you have, the metabolic “flexibility” of the mitochondria and the efficiency of your mitochondria.

With the increase in mitochondrial function from zone 2 fitness, your blood pressure will decrease, insulin resistance will improve (which prevents type 2 diabetes and metabolic syndrome), utilisation of fat and glucose as energy will improve, risk of heart disease will decrease, as well as risks for stroke, kidney damage, dementia and cancer all decreasing.

The benefits of zone 2 stretch far into function and performance, these benefits are seen in the lowering of your resting heart rate, improving your ability to train for longer, general longevity, and improving zones 4 and 5 function and performance. Zone 4 function improves your anaerobic capacity at 80-90% of max HR (your ability to convert glucose into energy), while zone 5 training, from 90-100% HR increases your speed training ability.

With the increases in aerobic performance, and the benefits from increased mitochondrial function, you may now be asking how to put these methods into practice. Elite athletes use a mixed training program of 80% being in zone 2, while 20% are harder efforts in zone 4 or 5. While these efforts are incredibly beneficial to the human body, studies show that over-training may reduce those benefits.

Studies suggest that training from 2.5 to 5 hours per week of moderate to aggressive physical activity converts to maximum all-cause mortality benefits. However, older studies do suggest that over 10 hours per week may reduce such health benefits (known as the reverse J-curve).

With all this in mind, keeping to an 80/20 program with easy and regular cardiovascular training, why wouldn’t you bring zone 2 training into your life?