By Dr. Ben Lerner
Your body will adapt or un-adapt to whatever stresses you do or don't impose on it. Consider these opposing forces.
Law of Adaption
If you run long distances, your muscles, joints, lungs and heart will adapt in a way that allows you to go the distance. This is a good thing, and the reason a marathon runner actually looks like one. And, if you're a sprinter, your body adapts for short distances. That's why sprinters look like and or train like body builders.
So if you want to improve stamina and cardio functioning, you run for a long time and your body adapts in a way to support that. If you want to increase strength and power, you do short sprints and you adapt for that.
If you want big, strong round muscles, you lift really heavy weights over a short period of time -- like a power lifter. If you want a more athletic build -- like a gymnast -- you lift weights or perform activities that create more sustained pressure.
Law of Un-Adaption
So what about the opposite action?
Whatever you're training for, you also "un-train" for. So a marathon runner doesn't make a great sprinter. Their lungs, heart, muscles and tendons are adapted for a completely different type of event. And, sprinters can't typically run a marathon. It would be like trying to ride a bull across country.
Your heart, lungs, circulatory system immune system, muscles and joints adapt to exercise by increasing their efficiency. So your muscles firm up, your joints lube up, the bones get stronger and thicker, your immune system gets cranking, your heartbeat strengthens, and your lungs and circulatory system dramatically improve their ability to take in, store and circulate oxygen.
On the other hand, if you do not exercise, your body un-adapts. Muscles get flabby, bones get soft and brittle, joints get dry, the heartbeat weakens and speeds up and you become oxygen deprived.
Exercise and Reversed Aging
People as old as 100 can dramatically increase their strength, improve their balance, restore bone density, moderate diabetes and diminish joint pain in just a few weeks of weight training. The minute you start sweating and your heart begins pounding, your arteries get more flexible and your blood pressure drops. This lowers your risk of heart disease and stroke too.
For hours after exercise, your body is more sensitive to insulin, keeping your sugar levels in check and reducing your risk of diabetes too.
Being in shape causes your heart and blood vessels to work only a fraction as hard as they do if you are out of shape. A conditioned person will have a heart rate of approximately 60 beats/minute. Someone who is out of shape will have a heart rate of approximately 80 beats/minute. This means if you are out of shape, your heart will have to beat approximately 30,000 more times per day than if you were in shape.
The purpose of weight loss is not only to weigh less, but to be healthier. Weight-reduction plans that use unhealthy foods, diet products, weird devices, drugs, supplements or even herbal "speed" to help you lose weight may make you lighter, but not healthier. When people ask me what I think about these plans I always say the same thing: "Sure, you might lose weight. You will die 10 years earlier, but at least you will be lighter."
The reality is, about the only positive thing about losing weight the wrong way is that you will make it easier on your pallbearers.
The fact is, better health does not necessarily come by simply losing weight. To improve the function of the Body By God operating system, there must be less weight and fat. It is not only how much you weigh that causes you to develop disease: It is how much body fat you have compared to how much muscle you have.
The point of exercise is to increase the amount of real muscle and decrease the amount of loosely packed muscle, or what we call "fat." Having too little lean muscle mass compared to body fat contributes to all sorts of conditions and diseases. High body-fat/muscle ratios negatively affect organ function, hormone balances, immune control, brain activity, blood chemistry and generally make you more sensitive to potentially hazardous food elements like sugar and cholesterol.
Diet alone cannot increase muscle mass and decrease fat mass. Only diet combined with exercise will increase your muscle/body-fat ratios. Through the law of adaption, the way the body adapts to exercise is by increasing your muscle-to-fat ratio. This will not only cause you to weigh less, it will cause you to have better health. Again, this will still make it easier on your pallbearers, but they will also have to wait a while before being called into action!
While many people rely on cardio activities alone and some on weights alone, to really get healthy you need both. You need to get your heart and lungs adapting in a healthy way through a regular cardio program and your lean muscle mass up by working out with weights or some kind of resistance.