We are making our way through Week 2 of The New Year’s Phase 1 Challenge as we build regular movement into our lives.
Today, we continue building up our practices as we turn our attention to wisely practicing cardio exercises.
Now, before getting into today’s main content, we need to have a little talk. The thing is, cardio has this strange reputation in today’s society, and if we all are going to be successful here, we need to clarify a few things.
The problem is that “cardio” has been flagged as a set period of time in which we push our bodies hard (running, biking, swimming, dancing, etc.) as we torch some calories.
Now, I’m not here to say that this mentality is all bad, but…
Wait, no. I am here to say just that – to say that there is a serious problem with the mentality that our cardio should be a set period of time a few days a week during which we push ourselves, work up a sweat, and torch a bunch of calories. Even more important, I am here to move us away from the perspective of aerobic activity as a grueling, often painful experience that exists because we eat too much and need to burn off the excess energy.
This mentality is not going to get us to our goal, and it’s time we fix that.
Cardio provides incredible benefit to the body for many reasons. One of these reasons may be because it helps us burn off some extra calories. But the benefits go much further, and if we can understand these then we can strategize how we work out so that we can optimize for our healthiest bodies.
Burning off excess energy when we work out is great. But, what we really want is to be able to utilize more energy more effectively all day long and not just when we are working out. More specifically, we want our bodies to:
- oxidize fats as fuel source so that they are not being stored in the body and instead are being used to fuel our bodies.
- efficiently utilize sugars as a fuel source when needed.
Most importantly, we want to do so in a balanced manner. We want our cells (and the mitochondria within our cells) to be able to use energy when it is abundant and to understand when they need to use sugars and when they should use fats.
That is, we want our cells to be insulin sensitive.
Let me explain this point, because this insulin sensitivity concept is key to a healthy body (which is why its opposite, insulin resistance, is the core driver of poor health and modern disease in The Reprogrammed Systems Model).
Your body uses two primary sources of energy-containing molecules (macronutrients) to produce ATP, the body’s useable form of energy. These two macronutrients are none other than fats and sugars. Most cells are capable of using either source, although there are important differences between the two:
- sugars are quicker to break down, thus providing a faster source of energy; however, they produce less energy per gram and produce more by-products, making them a little less efficient
- fats take longer to break down but provide more energy per gram
- sugars are burned first, followed by fats
All three points are important concepts to understand, and yet, this last point is what I wish to focus on as this balance of sugar/fat burning is essential for a healthy body.
When both sugars and fats are elevated in the bloodstream, the body is designed to preferentially use sugars before they do anything with fat. Once blood sugar concentration has decreased back to baseline, then fats are oxidized to produce ATP. This is a wise decision by the body because elevated blood sugar is acutely toxic. If the body were to ignore rising blood sugar levels and instead burn fats first, then that elevated blood sugar would be acutely toxic to cells throughout the body.
But the body is intelligent. It knows that it must first burn sugars and then turn the attention to fats. How does it do this?
Via insulin, a signaling molecule released by the pancreas that lets the body know that blood sugar is elevated. When insulin elevates, it serves as a sort of key that lets sugar into the cell (and then into the mitochondria) to be used to produce ATP.
So what’s the problem?
The problem is that an estimated 50% of the modern population is insulin resistant – that is, the cells that make up their bodies have lost the ability to effectively listen to the insulin signal in about half of the population!
To make matters worse, there’s a second problem.
In order to utilize fats and sugars (but, mostly fats) as a fuel source, each cell needs to have an ample amount of well-functioning mitochondria. This concept isn’t rocket science. If you want to use a fuel source to produce energy, you have to have enough factories and those factories have to be in good shape.
Unfortunately, the modern lifestyle does not support healthy mitochondria. Rather, the over-abundance of highly refined foods combined with the high prevalence of toxins leads to unhealthy mitochondria. Add to this the sedentary lifestyles that have become the norm, and we have a recipe for a field of dead or depleted mitochondria incapable of effectively recognizing the signals that they need to perform their job.
Now, the million-dollar question: how do we fix this with exercise?
My answer – by understanding the benefits of each type of exercise while also understanding some potential consequences. Then, we get to work establishing exercises that we think are best suited for our own bodies, lifestyles, and personal preferences.
To keep things simple, let’s focus on three types of cardio-based exercise.
- Low-intensity aerobic exercise (zone 2)
- Higher intensity aerobic exercise (zone 3-4)
- High-intensity interval (short bursts at max, zone 5)
Low-Intensity aerobic exercise
You can think of this zone as that area where you are moving your body but not quite really working up a sweat. You can still breathe normally and carry on a conversation, and yet you know you are working. For most people, this will be reached by walking or by a slow jog.
This zone is beneficial because it uses energy at a slow enough rate such that fats are being used preferentially while minimal glucose is used. While that may sound good for some obvious reasons (most of us love the idea of burning fat), let me turn your attention to some other specific benefits:
- since you are burning mostly fat, you are not burning much carbohydrate. Because of this, blood sugar does not drop and hunger hormones are less likely to elevate. This means that this lower intensity exercise is not likely to increase your appetite like other types of cardio tend to do.
- when done consistently, this type of exercise will signal to your body to build up your oxidative capacity – that is, to build the infrastructure (blood vessels, mitochondria, etc.) that are necessary to effectively oxidize energy, especially fats.
- when done consistently, this type of exercise will improve insulin sensitivity, allowing your cells to better understand when they need to utilize sugars as a fuel source and when they can use fats.
The trade-off: working purely in this zone does not give your body the acute stress that it needs to really improve quickly. If you can afford to spend hours in this zone each week, then you can build up healthier mitochondria and blood flow over time. However, as many of us don’t have the time to put in hours and hours each week to devote to this type of training, I suggest considering adding in some other types of activity.
High-Intensity Interval Training
This type of exercise is done in short (10-30 second) bursts of all-out effort, followed by a full recovery (2-3 minutes). This exercise works by giving the body a strong signal to improve, without actually leading to significant breakdown of tissue and need for long periods of recovery.
The easiest way to do this it to put on your running shoes or get on a stationary bike, and go sprint. Warm up for 10-15 minutes, and then go through 3-5 sets of all-out effort for 10-30 seconds, followed by a full period of recovery (1-3 minutes).
When you exercise in this manner, you put your body under a high load for just long enough that it hears the message, but you don’t go long enough to cause any breakdown of tissue or use up much carbohydrate. This means that you shouldn’t be too sore to exercise for the few days and that you shouldn’t feel the need to over-eat afterward.
The trade-off: this high-intensity should only be used if your body is ready for it. Pushing yourself into a sprint when your body is not ready is an easy way to cause injury. Also, if done correctly, you should not have too much soreness afterward, which may lead you to conduct this type of exercise too often. Therefore, I recommend that you only do this once a week and that you ensure your body is fully prepared before attempting.
The Middle Ground: Higher intensity aerobic exercise (zone 3-4)
This is the category that most people think of when we talk about cardio – the type of exercise where you put in a fair amount of time (30 minutes to an hour or so) and push yourself, working up a sweat for most of the time.
The benefits to this type of exercise include:
- elevated BDNF (brain0derived neurotrophic factor), causing great cognitive benefit including ability to learn
- endorphins – this type of exercise can make you feel really good, lifting you up and motivating you
- improved oxidative capacity – as discussed above with slower aerobic activity, this type of exercise can send a stronger signal to your cells to improve the ability to oxidize energy
- improved insulin sensitivity
The trade-off: this type of exercise burns lots of sugar and elevates stress hormones. This means it can lead to over-eating as well as cause an extra burden of stress on the body.
One final note here – a benefit of this type of exercise is improved oxidative capacity and insulin resistance; however, if the bad happens to outweigh the good, you could find yourself in a situation with elevated stress and hunger hormones driving you to produce behavior that leads to unhealthy outcomes like the excessive or irregular build-up of fat and insulin resistance.
As this is exactly what we wish to move away from here, I suggest being mindful of engaging in this type of exercise.
My Recommendation:
My central focus when it comes to cardio is to spend as much time as possible in zone 2. I make the effort to spend as much time as possible conducting this type of exercise:
- Because I greatly enjoy working out at a comfortable pace
- Because it gives me the excuse to be outside enjoying nature
- Because I understand the benefit is well worth the time
On top of this, I make sure to throw in the occasional high-intensity interval training. I’ll be honest here – I don’t do this nearly as often as I should. But, I understand that the benefit
I only use zones 3-4 for pure enjoyment or specific athletic goals. For example, if I find myself in a pick-up game of soccer or basketball, or feel the desire to go for a hard run, then I’ll end up putting in a strong cardiovascular effort for an extended period of time. Moreover, I purposefully spend time in this zone to build up the ability for my body to burn higher rates of energy because I have specific performance goals with racing and climbing.
Overall, following this sort of plan, the practice unfolds as such:
- spend as much time as possible in zone 2. For you, this probably means walking or a slow jog. Think about how you can get in more steps each day and how you can devote specific periods of time to fun outdoor activities.
- throw in a high-intensity workout each week, being extremely mindful of how your body responds.
- throw in the occasional middle-ground exercise, being extremely mindful of how you feel afterward. Are you feeling positive (motivated, uplifted, high-energy) afterward, or are you tired, hungry, and sore?
As you experiment with different types of exercise, ask yourself the following:
- Does this exercise make me feel good? Do I have more energy and motivation?
- Does this exercise make me feel poorly? Am I tired and sore? Am I hungry and leading myself to consume too much or to consume any industrial not-so-foods.
Of course, aim for the good, steer away from the bad, and change course accordingly. Remember, this is all about what works for you as you build your own healthy body.