Centuries of human experience have shown beyond doubt that exercise is a powerful stimulus for better health (1). Exercise also builds more efficient  muscles. Here we’ll discuss some simple reasons why you should exercise. I’ll keep it simple because that’s the level I understand.

            Most of you know this, but I’ll mention it so we’ll all be on the same page. Scientific investigators divide exercise training into two broad types, resistance training (think lifting weights or pulling stretchable bands), and endurance training, also known as aerobic exercise (think bicycling, walking, or swimming).

            Both resistance training and endurance training clearly benefit healthy individuals, and even most of those with illnesses as well. For example, aerobic training has been shown to improve functional capacity of patients with coronary artery disease, and resistance training improves their muscle strength and performance and even modifies their risk factors for heart disease. (Standard warning: unless you are in the full bloom of health, it is best to confer with your physician before beginning an exercise program.)

Resistance Training vs. Endurance Training

           So how does exercise perform its magic? Thanks to improving techniques available to study the activity going on continually inside our cells, scientists have shown that even a single bout of resistance training causes our muscle cells to synthesize more protein molecules. And it continues making more proteins for several hours after the exercise ends! The end result? Building more of these proteins causes the cross-section of muscle cells to thicken and that leads to bigger and stronger muscles.

            Endurance training also causes cells to build more proteins, but these particular proteins (mostly enzymes) are those largely involved in the oxidative metabolism of our muscle cells, This metabolism is vital. Without it we die. The interaction between oxygen and nutrients produces nearly all of the chemical energy we need to sustain our lives.

            The generation of energy by the metabolism of oxygen and nutrients takes place within our mitochondria, those tiny organelles inside of our cells. In fact, mitochondria are the power generators of our bodies. You probably know the interesting fact about the unique DNA in our mitochondria. That DNA is unique because it came entirely from our mothers. It is pure maternal DNA. The rest of our DNA (the major portion that is located in the nuclei of all our cells) comes equally from both mother and father.)

            Considering that both types of exercise increase the building of proteins, can you imagine a potential problem down the road? Maybe protein overload? No problem. Our cells live amazing lives. They know exactly what to do. As I mentioned in an earlier post, our cells are continuously in housekeeping mode, clearing out unwanted or damaged things and keeping everything in order. Much of this housekeeping is referred to as autophagy (2), which describes to the process of cleaning up cellular debris and breaking down damaged proteins into amino acids that become available for the construction of new proteins.

Autophagy and Mitophagy

           Fortunately for us, just as exercise boosts protein synthesis, it also boosts autophagy, a nice touch that keeps things in balance. So this means older, damaged proteins are broken down as newer ones are formed. This amazing process of autophagy is going on with varying intensity all the time in our cells, but it increases as we exercise.

            To be a tad technical, there is an important subdivision of autophagy, a subdivision that deals specifically with mitochondria, those unique energy-generating organelles mentioned above. Mitochondria are separate organelles in the cytosol, the stew-like liquid inside the cell but outside of the cell’s nucleus. This subdivision of autophagy has been given a name of its own. It’s called mitophagy, (short for mitochondria eating). This part of the housecleaning removes damaged mitochondria, a critical process for maintaining proper cellular functions. That’s as deep as I’m going to go here. If you are interested in more details, the somewhat simplified schematic diagram of mitophagy below should give you a head start into probing deeper into the subject.

            Okay, now to review and get practical, exercise enhances our health and wards off numerous ailments (1), probably in large part by stimulating autophagy and mitophagy. But how long does this effect last? And how much exercise is needed? Let’s take a look. As we’ve learned, endurance training increases the enzyme activity needed to facilitate the combination of oxygen and nutrients to produce the energy needed to keep our cells going. But these enzymes need fairly constant prodding. When one stops endurance training, say you’ve been walking regularly but suddenly give it up, it has been shown that the increased enzyme activity generated by your earlier walking begins to disappear when you stop, and it drops to “inactive” levels within 1 to 2 weeks of inactivity.

Take Home Message           

            So the take home message is simple. If you want to continue to enjoy the health provided by endurance training, or by resistance training, stay with it! According to the Mayo Clinic, one should get at least 150 minutes of moderate aerobic activity each week, or 75 minutes of vigorous aerobic activity over the same time period (3). The Clinic does add, however, that even smaller amounts of physical activity are helpful. And resistance training? Mayo recommends exercising all major muscle groups at least twice a week.

            I plan to stay with health and longevity for a while. Stay tuned!