Cardio. For some, it’s a dirty word; for others, it’s life. Many people flat out avoid doing cardio, some people relish in it, and many spend their obligatory hour on the treadmill each week so they can “check the cardio box.”
We all know that cardio training is necessary for health and longevity, but what is the right amount? If you’re not doing any cardio whatsoever your risk of all cause mortality is likely higher than it should be. On the flip side, if you’re doing too much cardio, say 8-12 hours a week at higher intensities (on top of a regular work and family life), there is a possibility that you are also increasing your risk of all cause mortality by doing too much.
How can we make sense of all this conflicting information regarding cardio? How can we know what is the right amount and what intensity we should be performing cardio at? In order to begin to answer these questions, let’s first look at what the cardio “zones” are.
Note: there are two models of cardio zones. A 5 zone model, and a 3 zone model. Both are relevant, but in this article (and the zoom class we will do next month) we will be talking about the 5 zone model.
What is the 5 Zone model?
The 5 Zone model is a means of classifying the intensity at which you are working out based on how your physiology is responding to that exercise, and what type of energy system you are utilizing at that intensity.
Zone 1 is considered to be an active recovery pace. Typically, zone 1 is considered to be at an energy output of around 50-60% of your max heart rate, and is easy enough that you could carry on at that pace without much discomfort for a very long period of time. Zone 1 is a great place to start for many people looking to get into exercise for the purpose of being healthier, and is also a great way for more seasoned athletes to recover from a difficult workout or race in the days prior.
Zone 2 begins to pick the intensity up a little bit, but is still a relatively light effort. Zone 2 is generally considered to be at about 60-70% of your heart rate max. In this zone you should be able to carry on a conversation with the person you are working out with relatively comfortably, while maybe pausing to take a slightly deeper breath occasionally. The purpose of this intensity zone is to bring you closer to your aerobic threshold, which is the point where your body can still primarily rely on oxidation of fat for energy, and not rely too heavily on glucose (blood sugar).
In zone 3 you have crossed through that aerobic threshold, and have gone slightly more anaerobic (anaerobic means without oxygen). Your breathing is becoming more labored and inside your body, your muscles are utilizing glucose for energy and giving off the byproduct of lactate. Side note: lactate is not bad. Your body is able to convert lactate into an energy source with the proper amount of training at zone 3 and zone 4, you become very efficient at utilizing lactate as an energy source as it continues to build in your blood stream.
Now you’re really working. Breathing is very labored, muscles are likely burning, and your heart rate is likely upwards of 80-90% of your max heart rate. This zone is very important for building speed endurance for endurance athletes as you are spending long periods of time burning blood sugar and lactate to maintain your high rate of speed.
Zone 5 is an all out effort. Think of 10 seconds sprinting all out as hard as you possibly can! Chances are you wouldn’t be able to maintain that super high level of intensity for very long. This zone is best for developing neuromuscular strength and power. It is an important zone, but not one you necessarily want to jump to right away.
With all these different zones, how do we know which one is right? How much training should we do in each zone?
First, zone 1 is a good starting point for many people. If you have not exercised much in recent years, zone 1 training could be as simple as taking a walk. Bodybuilders are famous for taking fasted walks first thing in the morning on an empty stomach to increase calorie burn. The ideology behind this is often referred to as “bro science,” but in my opinion, if it works for them, why not give it a try? Before you go any deeper on the other zones as you begin to exercise, start to go for long walks in the morning.
Zone 3 and Zone 4 is where most people end up by default. In fact, I would argue that many people spend way too much time in these zones (myself included in the past). Popular contemporary workout programs teach us that we should be spending more time at higher intensities for a variety of reasons (which I won’t get into in this article). Understand, that there are benefits to these higher intensity zones but people spend far too much time at these higher intensities and it may have deleterious effects both for health and performance.
If you’ve been to my exercise workshop, you’ve likely heard me talk about the difference between Honda building a car meant to last 300,000 miles vs Honda developing a car designed to win the Indy 500. When it comes to health and exercise, I want you to focus on building your Honda Accord to last you 300,000 miles with minimal maintenance costs. If you are training for a marathon, CrossFit competition, triathlon, or something similar, you will need to spend time in zones 3, 4, and maybe even 5 depending on the nature of your event; but you must understand that even the most seasoned athletes in endurance sports are spending 80% of their time at or near zone 2, and about 20% of their time in higher zones. This is referred to as polarized training (We will cover that more in depth in the zoom link I send out the BWCLP members in August).
This brings us to the intensity we should be spending most of our time at. Zone 2. Before we get too deep into Zone 2 basics, let’s take a trip back to high school Biology class and talk about the mitochondria, or as you likely remember referring to it as, “the powerhouse of the cell.”
Mitochondria in every cell are what converts fat and other substrates into energy for your body to utilize to perform work. Keep in mind that this will not be a scientific dissertation on mitochondrial function, but rather just the basics.
Everything we teach in the Be Well Chiropractic Lifestyle Program is designed to improve your metabolic health. The mitochondria is pivotal to developing a healthy overall metabolism. The more mitochondria you have, the more flexible they are (being able to utilize and convert both FAT and SUGAR to energy as opposed to just sugar), and their efficiency of function are all vital to your overall health. In fact, mitochondrial dysfunction is currently being linked to lifestyle related diseases such as type 2 diabetes, metabolic syndrome, heart disease, and even neurological disorders such as dementia.
This is where Zone 2 cardio comes into play. Zone 2 is right at the tipping point of your aerobic threshold, meaning that your mitochondria are utilizing oxygen (easy breathing, able to carry on a conversation) and fat for energy. This process is referred to as oxidative phosphorylation. Any more intense than your aerobic threshold and you are in anaerobic territory (less oxygen available and burning sugar for energy). In zone two we are deliberately trying to stay in that easier aerobic threshold to “teach” your mitochondria to utilize fat as energy resulting in increasing the number of mitochondria you have, improving their function, and improving their “flexibility.”
So, how do we know we’re in Zone 2 and how much time should we spend there?
First, understand again, that if you’re brand new to exercise, Zone 1 is where you begin. After accumulating improved work capacity at Zone 1, begin to elevate your intensity into Zone 2. There are 2 basic ways to tell if you’re in Zone 2. Neither are perfect but they are decent relative measures. The first one is the talk test. Before working out, read a short paragraph. I like the Pledge of Allegiance, not only because of my other job in the Air Force, but also because it is the perfect length for this test. Note how many times you take a quick breath while reciting the pledge. Then when you are running, periodically recite the pledge out loud and note how many times you take a breath. You should take approximately the same number of breaths during the workout pledge as you did at rest, HOWEVER, your breaths will be markedly deeper during the work out.
The next method is heart rate. The most accurate way to do this is to get your max heart rate tested and perform at approximately 70% of that heart rate, however that is expensive and time consuming and frankly unnecessary for the average person to do (unless you are an elite athlete). What I recommend doing is referred to as the MAF method, made famous by Dr. Phil Maffetone (who also used this method as a primary training technique for world class triathletes). The MAF method is simple, take the number 180 and subtract your age (180-age). That number is your maximum heart rate while training. So let’s say your out running and using a heart rate monitor, and your heart rate drifts over your max. Time to slow your pace or stop and walk until that number comes back down (this method can be followed on a bike, elliptical, pool, or whatever else you want, I just use running as an example because it’s easiest to talk about). Try to spend 30-45 minutes at this heart rate 2-4 times per week and build your way up to 45-60 minutes 2-4 times per week.
What’s the best amount of time to spend at this intensity each week? Well, that depends on the person. A safe bet is 10-15 running miles per week (or approximately 150 minutes a week on other exercise implements). While this may seem “slow” to you at first (surely, I can’t get a good workout training at this low of an intensity right?) over time you will reap the benefits that come along with consistency and it WILL improve your performance at higher intensities.
For our BWCLP members, keep your eyes peeled for the upcoming zoom link in your email, where we will go into much greater depth on this topic. Expect to see it in August.