It is a phenonmena observed every January--Resolutioneers mounting ellipticals, treadmills, stationary bikes and steppers.
Their goal is simple--get in better shape, lose a few pounds and fit into a pair of pants hanging in the back of the closet.
Cardiovascular exercise would seem to be the most straight-forward way to achieve that goal. Burn more calories, lose fat. It works for everyone for about two or three weeks, then something happens--the simple logic breaks down, fat loss stops and in many cases people begin to gain the fat back.
The resolutioneer quits in frustration.
By mid February the traffic in the gym in back to normal, the pants still hang in the back of the closet.
How can something so logical as burning more calories through cardiovascular exercise not result in sustained fat loss? The answer is in your body’s ability to adapt to exercise and the complex functions of the hormone cortisol.
NOT SO SIMPLE MATH
The conventional wisdom of cardio is the energy in vs. energy out formula. Burn more calories than you eat and you will lose weight.
But for many people, probably the majority or people, the simple math never delivers on the promise over the long haul.
“If the energy in, energy out concept actually worked, you could cardio yourself out of existence,” said Lisa Krog, a trainer of elite physique athletes in South Africa.
Lisa and her husband Glen give the following example when talking about while the simple math does not work.
“If you did enough cardio every day to burn 500 more calories than you ate, after a few years you would simply not exist. But all those people putting in hours on the cardio machines for years still exist.”
Of course that assumes they are on a controlled eating plan to ensure they are eating less than the burn. But the simple fact remains that even if you did create a 500 calorie deficit every day through exercise you will not be able to exercise yourself out of existence. Your body will adapt to the workload.
The simple conventional wisdom does not take into account that your body will adapt to the new normal. To stay one step ahead of you body you need to apply the Rosenfield Rule and gradually increase the duration or intensity of the cardio.
This increase in exercise will extend the weight loss benefits of cardio a little longer, but ultimately becomes counter productive to fat loss because of how the body adapts to cardio vascular exercise and complex actions of the hormone cortisol.
FLABBY RUNNERS
Cortisol is produced in the adrenal cortex of the brain as a response to stress--just about any kind of stress--including exercise which is what we will focus on here.
Exercise stresses the body. When the exercise load exceeds a critical level, which is different for each person, the adrenal cortex secrets a massive amount of cortisol. It is not a one-shot secretion. The longer the level is sustained, the more cortisol is released.
According the University of New Mexico’s Len Kravitz the critical level that results in excess cortisol secretion occurs after about 45 minutes of exercise--some people hit the critical level earlier, others later depending on variety of genetic and other variables.
Two of the effects of excess cortisol are fat retention, it makes your body want to hold on to fat instead of burn it, and muscle catabolism, it makes you body use skeletal muscle for energy.
The muscle catabolism is most pernicious effect of cortisol for people trying to lose fat.
A pound of muscle burns about five to ten calories a day even if it is not worked. While that may not seem like much, in one day, it can add up to 3,650 calories a year or about on pound of fat. Four pounds of muscle can burn four pounds of fat. A loss of four pounds of muscle could result in a gain of four pounds of fat.
When cortisol puts the body in a catabolic mode while doing cardio vascular exercise the muscle is burned instead of fat. For every pound of muscle that is burned, your resting metabolism slows down a little bit.
If your energy intake from food is not adjusted to the loss of muscle, you have a calorie surplus and will gain fat while doing lots of cardio.
This it what causes the flabby runner effect.
In every decent sized city there are a few running clubs whose members log 30 or more miles a week. Some of the members have lean physiques, some look remarkably average and some are just plain flabby.
The flabby runners kick out a lot of cortisol, do not have much muscle and do not eat a controlled diet. All that cardio has made them very fit, but it has also made them fat.
The few who are lean have bodies that, for a variety of reasons, respond well to long-term cardio vascular training.
If cortisol’s burning off of muscle tissue wasn’t bad enough, cardio vascular exercise also changes the way your muscles repair themselves which inhibits gaining muscle tone and can have a less than desirable effect on your appearance.
MITOCHONDRIAL MESSAGES
When a person engages in overload weight training, especially higher intenstity training, the body is sent a signal to increase contractile protein synthesis. This signal is part of muscle hypertrophy and leads to increased muscle tone, size and strength. Contractile proteins are what make person’s arms look good.
Overload weight training is the time-tested way to increase contractile protein that increases the muscle tone and size that leads to a firm physique.
The extra muscle also speeds up the metabolism just a little bit.
Cardio vascular exercise sends a different signal.
Rather than increasing the tone and size of the muscle cells, it sends a signal to the mitochondrial mass to enhance energy production. The signal to the cells is to switch from contractile muscle to the smaller mitochondria. This results in less muscle tone, size and shape.
Glen Krog sums up the various unintended ill effects of cardio vascular training like this:
First, cardiovascular activity is very efficient at chewing up muscle tissue, the steps are as follows:
1. Conversion from fast twitch muscle fiber to slow twitch muscle fiber, by acquiring mitochondria and relinquishing contractile protein. Smaller fiber, less RMR.
2. Excessive Cortisol released in response to the damage to the fiber as a result of the exercise. Cortisol acts as a natural analgesic, but severely hampers protein synthesis and muscle repair.
3 . It has been shown, that high volume cardiovascular exercise can completely deplete satellite cells in muscle fiber, which means no new fiber can grow or existing fiber be repaired.
4 . Growth Hormone levels decline with high volume cardiovascular exercise, which also hampers the repair process. Low growth hormone also accelerates aging.
5. To sum it up, you can’t train all day, and you can’t eat no food, but you can always build a bit more muscle, so quit the cardio and concentrate on the weight lifting.
The question on a person’s mind right now is, if cardio only works for a few weeks until the work load must be increased, then you get to a point that the body produces excess cortisol that burns up muscle, and cario shrinks muscle size--what kind of cardio can be done?
The answer is good old fashioned sprints.
HIIT
The modern term for sprints is High Intensity Interval Training or HIIT. This type of training can be done on a treadmill, elliptical machine, stepper, stationary bike or outdoors anywhere there is a flat surface for 100 meters.
I prefer to run my sprints outdoors in a parking lot down the block.
In HIIT you alternate between periods of high intensity and low intensity. A person does not need to go as hard and as fast as they can during the high intensity--they just need to go hard and fast enough to get the heart and lungs working. The low intensity periods can be like a power walk, or a nice medium pace.
The time intervals are flexible. Most people do not go past two minutes during a high intensity period.
A two minute period of low intensity is generally the longest most people go before cranking it up again.
Here’s an example of me running sprints so you can get the basic idea.
The Rosenfield Rule can be applied to HIIT in a variety of ways. A person could add one more high intensity interval each week. The speed/difficulty of the high intensity interval could be increased. The time of the low intensity intervals can even be decreased.
http://www.fitforcombatsystem.com/resolutioneers-project-rosenfield-rule/
In the video above, my goal was to do the same amount of work in less time than the previous week. The time period would be shorter, but with a greater intensity which keeps my body from adapting to the work load and one step ahead in the energy in vs. engergy out equation.
The advantage of HIIT, especially old fashioned sprints, when compared with traditional cardio is that it minimizes some of the ill effects of cortisol and how the muscles adapt to the work.
Cortisol will still be released during HIIT, but the low intensity periods moderate the release. In traditional cardio, once the critical level is reached, the body pumps out massive quantities of cortisol while a person is exercising. HIIT workouts tend to be shorter which also minimizes the amount of cortisol secreted by the adrenal cortex. A person can do a killer HIIT workout on a machine in 15 minutes. It is not the time the counts, but the intensity of HIIT that burns the calories.
The primary advantage of HIIT, especially short sprints outdoors, is the recovery/repair signal sent to the muscles. A sprint is almost like a weight lifting set--a short burst of maximal effort involving the fast twitch muscle fibers--followed by a period of rest. The repair/recovery signal is hopefully to build more contractile protein rather than mitochondria.
Losing fat through cardio is lot more complex than the simple energy in vs. energy out formula--which is why so many people who just do cardio never achieve their fat loss goals.
Cardio is great for the heart, lungs and overall health, but for fat loss, a person has to keep in mind the body’s ability to adapt and the side effects of cardio like cortisol and loss of muscle tone and size.
If a Resolutioneer trains a little smarter, and a little harder each week using the principles of HIIT, the results can be amazing.
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