Rethinking Cardio

While I’m not typically big on consistency, I do make exceptions when it comes to a few things, mainly my Morning Flexibility/Mobility Routine and my commitment to continuing to raise the bar in every area of life. Reflecting on how much my perspective on exercise was forever altered by a single Mark’s Daily Apple post called A Case Against Cardio, it’s clear that ever since reading this piece years ago, what was once a major aspect of my life has morphed, transformed, and now been completely upgraded (for the better!).

It is also interesting to witness how the validity (and popularity) of some health trends can get completely obliterated by the discovery of new research, while certain practices have fallen under the umbrella of “conventional wisdom” for so long that it seems unlikely that some people will ever fully retire them. One of the most widespread and long-lasting examples of this? Chronic cardio.

Just think about it for a second. How many people do you still see running (not sprinting) when you head outside? There seems to always be at least half a dozen people hitting the pavement hard, looking more exhausted with each passing second that they continue to push their body past the limits of what it seems to be comfortably capable of. I myself have noticed there are still so many people out there (sharing progress on social media or just in the world) who continue to put in countless hours for cardio, and I believe it is important to examine exactly why this poses such a serious problem. 

The unfortunate truth about cardio is that this activity we all once thought of as a healthy habit has actually turned out to be anything but that. And most importantly, new research suggests that all kinds of exercise will deliver a cardiovascular training effect (this includes walking and even intense workouts like strength training and sprinting), which makes you wonder: why even bother with cardio? Especially when you consider how Dr. Peter Attia describes the effect it can actually have on your cardiovascular function: “Challenging endurance workouts cause an increase in both heart rate and stroke volume [amount of blood pumped out per beat of the heart], by stretching the heart larger to pump more blood per beat. This amazing organ can quickly go from pumping three to five liters of blood around our body per minute at rest to 30 liters per minute during very intense exercise. Unfortunately, the right side of the heart, which pumps only against the low-resistance lungs, and is far less muscular than the left ventricle, is more vulnerable to damage from chronic amounts of high cardiac output training. So while short bouts of this intensity don’t appear to cause lasting damage on the heart, prolonged activity does — at least in susceptible individuals. The so-called chronic cardio patterns can cause the right ventricle to become scarred from excessive use and insufficient recovery. This scarring can lead to cardiac arrhythmias, especially atrial fibrillation, and even sudden death in athletes who have no evidence of atherosclerosis.”

Another big issue lies in the way chronic cardio’s effects cause damage to mitochondria. Mitochondrial DNA actually leaks out of your cells when proteins become denatured, and this happens when mitochondria are heated up too frequently, for too long. This is dangerous because our body actually perceives mitochondrial DNA as a foreign agent, but one that is also unfortunately super similar to bacteria cells. So when mitochondrial DNA starts leaking into your bloodstream, it sets off the alarm in your body to trigger an inflammatory autoimmune response. And while your body is confused, it will still be on the attack for what it believes is a foreign invader to its system, resulting in your body essentially attacking itself. So, not only is chronic cardio horrible for your heart, but it’s also terrible for your gut health!

Need more convincing? Just check out what Dr. Doug McGuff (author of Body By Science) and Dr. John Jacquish (Weight Training Is A Waste Of Time) have both written about the way a rigorous cardio schedule will alter your body: it can actually tank male hormones, prompt muscle catabolism, promote fat storage, and suppress immune function! 

Thankfully, research has shown us that there is another way to receive cardiovascular benefits without totally completely trashing your health, and this is by engaging in brief, high intensity workouts. This kind of workout offers far superior benefits compared to what happens after you do steady state cardio (not to mention, in a fraction of the time too!). Challenging your muscles to deliver explosive, near-maximum efforts prompts a burst of adaptive hormones into your bloodstream, which is an optimal activation of the fight or flight response. If performed correctly, these explosive workouts (think sprints, jumps, kettlebell swings, or using an X3 bar or hex bar to deadlift) will not leave you exhausted and sore. Instead, you will find that you feel energized and alert. And as your body recalibrates back to homeostasis, testosterone and human growth hormone work their wonders to make you stronger, leaner, and more energetic.

So what do you do when you know it’s time to move past steady state cardio, but you don’t know where to start? One easy way to jumpstart this shift can be found via my YouTube channel, in my video Jogging 2.0, where I showcase a few alternate options to cardio. These exercises are challenging but creative, and surprisingly fun to perform. You can also always do sprints (be sure to check out my Running Drills video first, as well as How To Do A Spring The Right Way) and simply just take walks and power walks!

While taking a walk may seem like the basic or boring option, it’s actually extremely effective (not to mention easy to do!). Simply just walking can be a highly therapeutic and calming experience, but you can also make it more fun by listening to podcasts, an audio book, or music. And, like I mentioned, it’s also just really good for you — listen to my show with Katy Bowman if you want to learn more about how deeply effective this seemingly simple practice is. Katy says: “I do long distance walking. I really need to walk — there are body parts I can’t even get to without walking 20 miles.” Interestingly, a UCLA study focused on the elderly found that walking more than 4,000 steps per day resulted in a thicker hippocampus, faster information processing, and improved executive function. 

Whether you’re walking or sprinting, the most important thing is to stay mindful and informed so you can avoid afflicting any long-term damage to your body. I share a lot of clips from my workouts on Instagram, so click here to follow me if you want to see the different kinds of movements and exercises I enjoy doing now. And if you’d like to read even more about this subject, I have also written a two-part piece about the risks of running for Mark’s Daily Apple, which you can read here (part 1) and here (part 2).


Brad Kearns
Brad Kearns
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