I personally don't know where the popularity for "cardio exercise" has stemmed from, and neither have I come across any convincing evidence over the last ten years that this kind of activty should be our number one priority for improving long-term health.
First of all, what happens during a bout of "cardio" anyway? What actually improves in our body? And how does this relate to our definition of health?
Common things that happen during a bout of cardio:
- Our heart beats faster. So what?
- We burn calories. How many and what does this improve?
- Our lungs are filled with oxygen. How does this help us improve our health?
- We sweat. But so do we going to the sauna.
- We release endorphines. But so does eating ice cream or going for a ride on the rollercoaster.
So what does "cardio" actually improve in the body, and why do we still see a large part of the finess community dragging themselves through 50 minutes on the treadmill or a 10k run on the road?
This is what ALSO happens in the body when we do frequent bouts of "cardio" - especially when done excessively and frequently:
As Dr James O'Keefe, cardiologist and Professor of Medicine at University of Missouri points out, aerobic exercise causes "structural cardiac changes" as well as "elevations of cardiac biomarkers" which when produced in excess through frequent aerobic exercise leads to "patchy myocardial fibrosis, coronary artery calcification, diastolic dysfunction, and stiffening of arterial walls."
Dr. O'Keefe goes on further to say that "If you went for a run today and you ran hard...by 60 minutes something starts happening: the free radicals blossom, and they start burning the heart. It starts searing and inflaming the insides of your coronary arteries."
"Cardio" - when taken up on a regular basis - leads to excess free radical production and oxidative damage - which makes you age prematurely as well as increases your risk of suffering degenerative diseases. If your goal is to live longer, exposure to excess free-radical production should be avoided at all costs. The damage caused by this kind of mechanism favours the development of many chronic diseases - including cancer, heart disease, obesity, brain disorders, arthritis, and many others.
"Cardio" further comes with the cost of excess cortisol production in the body which is a major trigger of systemic inflammation, muscle loss, as well as other catabolic (i.e. tissue-degrading) processes.
In comparison, this is what STRENGTH TRAINING does to our body:
- Strength is the number one physical predictor of longevity (and not our ability to complete a 10k run)
- Muscle mass - which is a function of strength - is the second biggest predictor of longevity. Have I mentioned that cardio sacrifices muscle mass?
- Strengthening bones, joints, ligaments, and tendons - tissues which ONLY respond to progressive overload placed upon them as seen with an increase in weight on major strength lifts (squats, deadlifts, presses,...)
- Improved mental health as the increased amount of weight lifted over time develops discipline, increases motivation, as well as creates daily events of success which contributes massively to a more positive outlook on life
- Strength training has anti-inflammatory, anti-oxidative, anti-catabolic properties as it bumps up rejuvenation hormones such as testosterone, growth hormone, and IGF-1.
Cardio is the antidote to strength training: reduction in muscle mass, drop in rejuvenation hormones, and accelerated aging.
The argument "I enjoy running and that's why I do it" does not justify the selection of an exercise activity that does not serve our health in the long run. Enjoyment can be achieved in many different forms elsewhere.
If option A promotes health, and option B accelerates aging, which one would you choose?