Cardio. A word that people either loathe or love, or love to loathe. A word that is highly advertised as a form of weight loss by gyms and trainers alike, but more often than not, it is a word that is misunderstood.
In the health and fitness world, cardio is slang for cardiovascular activity. Cardiovascular is a fancy term that combines two words into one to describe a system: “cardio” and “vascular,” which are both from the Latinized form of Greek “kardia” and “vāsculāris,” which mean “relating to the heart” and “relating to the vessels,” respectively. In a sense, this is a very broad term. However, fitness enthusiasts and scientists alike have tried to put a definition to cardio, and if you were to do a quick Google search, you’ll find definitions along the lines of, “exercise that increases heart rate.”
This definition sounds extremely simple, but at its essence, cardio is exactly that. It is any exercise that elevates the heart rate above resting level. When heart rate increases, such as from the onset of exercise, the heart is working harder to deliver oxygenated blood to the now working muscles via blood vessels. Since the activity involves a heart and some vessels, it can be deemed as a “cardiovascular” activity.
So, if the word is this simple, how is it being misunderstood? It’s because we’re almost strictly relating cardio to weight loss and calories burned, and we’re unknowingly destroying our bodies while trying to accomplish those two things. We’ve fooled ourselves into thinking that “good workouts” are the ones where we leave drenched in sweat, the ones where our FitBits give us a virtual high-five for burning so many calories.
Let’s consider a couple of the biggest trends in today’s fitness world: high-intensity interval training (HIIT) and heart rate monitors. There has been a significant rise in HIIT-focused gyms that utilize heart rate monitors to show their clients how hard they’re working, and encourage them to get their heart rates high by rewarding them with bonus points or what have you. The gyms then inform their clients that HIIT is the best way to accomplish weight loss because it leads to a high caloric burn, and includes the benefit of a huge post-training caloric burn due to excess post-exercise oxygen consumption (which research has shown to be a sensational claim that is blown way out of proportion, but that’s an argument for another time).
Am I saying that HIIT is bad? No. Am I saying that heart rate monitors are bad? No. HIIT leads to several physiological benefits outside of expending the most amount of calories in the shortest amount of time, and the utilization of heart rate monitors during training is very helpful when it comes to determining intensities and one’s ability to perform that day. What I am saying is that we’re being led to believe that cardio must always be hard, and that we must frequently aim to get our heart rates high so that we can burn as many calories as we can and lose weight quickly. In doing so, we’ve increased our risk of acquiring injuries because we’re trying to do too much when our bodies are only capable of handling certain amounts at certain times.
First, let’s look at what’s happening to the body during something as simple as walking. As your foot makes contact with the ground, ground reaction forces that are equal to the amount of force that you applied to the ground now act opposite onto the foot (Newton’s 3rd law, for you physics nerds), and are being transmitted across your joints via joint reaction forces. Without losing you to numbers and equations, we’re talking nearly THOUSANDS of Newtons (i.e., the unit for force) acting on the body by just walking. This number increases even more when more high-intensity movements are involved, such as running or jumping, and let’s not forget about the impact of gravitational forces. Sum up the number of foot ground contacts during your long bout of high-intensity exercise, multiply that by the forces acting on the body, then multiply THAT by the number of times you perform the exercise in a given week… That’s a lot of forces that you’re asking your joints to handle.
Now, let’s take a look at the statistics. According to the National Safety Council, overexertion is the second leading reason that adults between the ages of 25 and 64 years seek medical attention (1). Overexertion can be caused by performing an activity at an intensity that is well beyond one’s limits, or by excessively performing an activity at certain intensities. According to a 2014 study by the U.S. Department of Health and Human Services, an average annual estimate of 8.6 million sports- and recreational-related injuries was reported, with GENERAL EXERCISE being the most frequently mentioned activity in injury episodes (2). Furthermore, a 2015 study found that overexertion accounted for the greatest amount of injuries sustained within a fitness facility (3). With a significant increase in gym-goers worldwide (let alone a significant increase in certified fitness professionals) (4), we’re also seeing a rise in injuries, with overexertion injuries apparently leading the way.
Combine the biomechanics with what the statistics are telling us, and we can see that we have a problem. We’re simply doing too much to our bodies; we’re training intensely, but not smartly.
When we choose to implement cardio into our training, we do so under two misguiding principles: that we need to exert as much as we can within the shortest amount of time to burn the most calories, and that we need to do it as often as we can to quickly drop as much weight as we can. People, this is not the way to go about cardio. You will burn out from the accumulated fatigue. Your body won’t recover efficiently due to the amount of damage to the muscles, tendons, and ligaments exceeding the body’s rate to rebuild itself. You will injure yourself.
What we need to do is shift away from the “do more” mindset with cardio. Stop relating cardio to the number of calories burned, the amount of sweat produced, and/or the amount of weight lost. Certainly, it’s always good to get a sweat going and intentionally aim to burn calories off every now and then, but this shouldn’t be the driving factor to your training. Instead, start treating cardio as a means to “be able to do more.” The more efficient your cardiovascular system, the better you’ll be at sustaining exercise and recovering from it. You’ll feel better in the long term because your muscles and joints will be challenged in a smart, healthy manner. You’ll be able to go on long walks with your dog, survive those long yet beautiful hikes in nature, or play longer with your kids. The quality of cardio is far more significant than the quantity, and this is coming from someone who was able to train for and complete a 140.6-mile triathlon when the farthest race she had finished prior to it was a 5-mile run while wearing a Santa Claus suit (I’m in the Guinness World Record book for the Santa Claus suit, believe it or not).
My point is this: your quality of life, which implementing cardio can improve, is way more important than the calorie number that haunts your FitBit.
In the second part of this two-part series, I will share with you the physiological benefits of cardio, and how to include cardio into your training in a qualitative manner.
1 National Safety Council. Injury Facts. Itasca, IL: National Safety Council; 2016.
2 U.S. Department of Health and Human Services. National Health Statistics Reports: Sports- and Recreation-related Injury Episodes in the United States, 2011-2014. Hyattsville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention; 2016.
3 Gray SE, Finch CF. The causes of injuries sustained at fitness facilities presenting to Victorian emergency departments - identifying the main culprits. Inj Epidemiol. 2015; 2(1): 6.
4 Nielsen Global Consumer Exercise Trends Survey. Consumer Fitness Trends Statistics & Insights for Fitness Facilities. Nielsen; 2014.