Hi!
Simply Eat Less.
In my experience in the Health & Fitness Industries over the last 3 decades, I have found that the decision to include mega-loads of cardio or hardly any at all swings through the bodybuilding culture like the pendulum of a clock.
There’s a new fad with a new name every few years or so, backed up by some new (limited) study and an awareness marketing campaign led by some famous ‘celebrity’.
Many who favour cardio claim that it allows them to eat more. That is good, right? Eating more is anabolic, isn’t it?
On the other end of the cardio spectrum, supporters of LESS CARDIO insist cardio is the most catabolic thing that can be done. They claim that it has to be avoided.
Solution they come up with: simply eat less.
So, should you do more or less cardio?
I won’t pretend to try to solve this dilemma but I will give you some facts, as I see it and have experienced it. Hopefully, it takes you closer to the doorstep of your ultimate condition.
The 80:20 Principle.
First, let’s clarify what is the actual goal in terms of physiology?
Based on one of Nature’s Principle (the 80:20 principle), the vast majority of “fat” in our body (over 80%) is collected in one form and stored in body fat cells.
The process that the body uses to consume this energy and effectively get rid of it – is called lipolysis.
I’m going to try to detail the mechanism of this process with exercise (avoiding diet for now).
In my experience of helping hundreds of individuals over the years is that I find that The difficult part is when : we have to apply these “truths” to the many different circumstances and body types that we find in the sport of Physique Artistry/Bodybuilding.
Everything is hormonal-driven.
Activity-related hormones epinephrine and norepinephrine speed up lipolysis greatly.
When we start working out, we firstly use the readily available energy in our blood, called GLYCOGEN. The body starts shuttling out these glycerol and fatty acids (fat) from our body fat cells.
research shows that the greatest increase in fat usage starts immediately upon exercise, hits a peak level within 5 minutes, sharply decreases, by the 15-minute mark starts to plateau, and within 30 minutes is back almost to a rate matching a control group.
So, what do we do with the common knowledge that carbohydrates (blood sugar/glucose) are used exclusively for the first 15-20 minutes of cardio?
As most of you are aware, blood sugar is the dominant source of energy used by the cells of our body at the start of exercise. As you do cardio, the body digs into longer-term energy stores, the liver (through the action of the hormone glucagon) starts pumping out stored glycogen and as described, body fat cells start releasing glycerol and fatty acids.
The question we then ask ourselves is – does the liver run out of glycogen? When it does, what happens then?
As long as Body Fat is available …
It is quite obvious that When we are exercising, we are moving the body towards an Energy Deficit.
My understanding is that the body & in particular, The liver, tries to contribute to the energy deficit.
How does it do this?
it does so by converting amino acids into glucose. I’ve learned that the liver has a reservoir of aminos available. Despite this, this process is STILL a catabolic phase. And what is “catabolic?”
It simply means “muscle wasting “ or muscle deterioration.
Interestingly, though, even during the harshest, longest bouts of exercise, studies show that only 3 to 6% of energy is consumed from amino acid use.
As long as fat is available, the body spares protein as if it were the most precious commodity it has. Nice to know the brain agrees with us on that one. We need to dig a little deeper to get a better understanding of how the body tends to operate.
There are many variables we need to bring into the equation before we even address things like duration, frequency, and intensity.
Even a small percentage of amino acid use can add up if it’s a repetitive occurrence. I also mentioned “as long as body fat is available”…
Body Type.
Many individuals don’t get to that stage (under 10% body fat) to worry about not having sufficient body fat available to be used as Energy, during exercise.
The variable of BODY TYPE is an important consideration when deciding HOW MUCH CARDIO an individual should do. There are 3 main body types – ectomorph, mesomorph and the endomorph.
What is your body type?
In my experience, An Ectomorph, has to have a healthy fear of “too much” cardio since they will be at the top end of the population in terms of using amino acids for energy. The more, the better, in their case.
In the middle of the spectrum, those that lose moderately slowly (like me) need to understand that muscle preservation is their greatest asset. We need to see cardio as a very necessary part of their daily habits and any kind of preparation for competition.
It has been and still is, a KEY daily habit of mine.
On the other end of the spectrum, you have the Endomorphs. For these individuals, more, rather than less cardio is the way to go. They usually have a lower metabolic rate to begin with and tend to carry a very high level of fat deposits.
The more cardio, the better.
The Rate of Lipolysis.
Here is where armchair interpreters of research often start showing that it takes more than throwing some big words around to master the subject.
KEY FACT: The rate of lipolysis is virtually unchanged whether we’re at just 25% of our VO2 max or 85%.
That means that whether you’re walking on a treadmill or slamming out 30km/hour sprints, your body is releasing the same amount of body fat to be used.
Before you say, “Aha!! I knew that slower, longer cardio sessions were the right thing to do,” don’t!
You first have to differentiate between just releasing fat to be used and actually using it.
If you maintain a slow or high pace, a percentage of the energy will come from your fat cells . That’s a given.
In the case of the former, even though the body is releasing fat to be used, when it’s not used, it simply resynthesizes the glycerols/fatty acids and re-stored as body fat.
So, we then ask other key questions like:
1. Due to a slower rate of usage, should one just perform a longer duration and ultimately use the same amount of calories as someone doing a shorter but harder session?
2. Which will use more body fat and which will be less catabolic?
You should Keep in mind that the body has a vested interest in using these fatty acids for energy.
It doesn’t take a rocket scientist to deduce that Glucose and glycogen (the energy currency of our body & brain 🧠), aren’t in endless supply.
It’s obvious that when activity levels increase, the body needs to turn not only to its larger material source of energy, but it wants to be efficient at it. Remember that – it wants to be EFFICIENT AT IT.
As the RATE OF LIPOLYIS is increased, so is the blood flow to the exercising muscles, and so are the chemical processes that convert the fatty acids into usable energy.
TWIST IN THE ROAD.
Here is yet another twist in the road.
As intensity increases, these glycerols are used at a higher rate – a good thing. But, when exercise intensity reaches a level where blood flow is necessarily shunted more sharply to the working muscle tissue, blood flow to the available fat stores is restricted tremendously, decreasing the rate of fat that is made available to be used as energy.
That is why I tell all my former students that the OPTIMAL TIME to do cardio & burn more fat is first thing in the morning, upon waking and … on an empty stomach.
Like I said earlier , If we perform light cardio we release just as much body fat as high-intensity work. What is the risk of losing muscle here?
Answer: the risk of losing muscle is low.
However, but then due to a slower rate of fat usage, we simply re-store the released body fat.
So, you may be thinking – “why don’t We just do longer sessions of low-intensity cardio?”
Yes, you could but it would not be the most effective use of your time. And why?
Well, research shows after 30 minutes, fat release actually decreases – not increases as conventionally taught.
Trying to keep every variable straight is like trying to catch a greased pig. It’s like the squirrel in the animated movie Ice Age; as soon as you stick every available finger and toe in the leaking wall of ice, another confusing point of physiology springs out of a new crack.
No wonder there isn’t a consensus on the subject.
As I mentioned in the beginning of the article, you would be making a mistake if you take this article as covering every facet of the subject – think of this as just an outline and the book isn’t finished.
ACTION PLAN.
Read on for an action plan…
The ease of your body’s ability to burn body fat will affect how much cardio you do. This is depended on your body type & genetics.
Being that all of cardio is catabolic, you want to do the least you have to in order to be shredded.
For some that may mean twice a week and for others that may mean twice a day.
Consider two glaring facts:
One: Your body immediately starts releasing body fat with exercise and continues for 30 minutes until the law of diminishing returns virtually eliminates any further benefit.
If we are going at too slow of a pace, the released fat gets re-stored and if we get too high in our intensity, we shunt blood flow away from fat cells. As such, I believe, there are two types of cardio that we can benefit from and still meet our goal of sparing as much muscle as possible.
The first is thirty-minute sessions at a good pace – heart rate sustained at 130-150 beats per minute for most people. Remember, even at just 25% of our VO2 max we’re going to be releasing all the body fat that we can, but we need a pace that will actually use what is released, but not so much intensity that the body goes into a fight-or-flight mode channelling blood to the muscle tissue systemically and away from the adipose cells and organs.
The best natural bodybuilding athletes/champions know and understand how to do this better than almost everyone. Their “Double-edged sword” of keeping /maximising muscles and maximally losing fat is the challenge /opportunity.
I also believe the value of super-high-intensity cardio is tremendous but you have to weigh the catabolic effects and the fact that it won’t take long to be counterproductive and decrease the amount of fat actually being released (due to the changing blood flow patterns).
I would recommend using high-intensity sessions 1 to 3 times per week for 15 to 20 minutes to create longer-term fat usage through the increased metabolic effects.
Ectomorphs may have plenty by doing just 10-minute high-intensity sessions, but even endomorphs shouldn’t do more than 2 to 3. The amount of actual leg muscle recovery necessary should be a limiting factor – you’ll need to recover almost like a leg workout.
Base-line
The “baseline” 30-minute sessions could be done daily or even twice a day for those who lose weight slowly or have more lower body stores to contend with.
That doesn’t mean that longer, slower cardio is worthless, you just get a fraction of the fat loss after the first 30 minutes.
Breaking up an hour of cardio into two sessions can net more fat loss if the pace is high enough and consistent. This is what I do. I try to do 30 minutes walk in the morning on a treadmill and another in the evening if I have the time.
The great thing about human performance research, however, is that we’re still very much in a pioneering phase.
Studies conducted with different variables keep adding to our understanding and more specific information is sure to be discovered.
For now, this is my story and I’m sticking to it.
Keep safe. Keep punching,
Until next time,
P.
Changing lives. Empowering people. One life at a time. 
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