Hand in Hand
Nutrition and physical activity go hand in hand. The working body demands energy-yielding nutrients to fuel activity. And, it needs protein plus supporting nutrients in order to build lean tissue. Exercise requires the body to dip into its stores of fuel namely, fat and glycogen. By using up fat and building lean tissue, exercise pushes body-composition toward lean and thus, raises the body’s rate of energy expenditure (active metabolism). To contrary, a lack of exercise, or an “exercise deficiency” can lead to accelerated development of disease associated with sedentary life — cardiovascular disease, obesity, intestinal disorders, apathy, insomnia, accelerated bone loss etc.
Want Good Looks? Boost Your Metabolism
For the person seeking health or wellness, physical activity is as important as nutrition or sleep. It promotes fitness. And, since a fit body looks healthy and attractive, it enhances appearance. To understand exercise we must first refer back to metabolism. The term metabolism refers to chemical reactions that take place within the body. As explained earlier, metabolism is the sum energy expenditure of all bodily functions. It is the amount of energy our bodies require and burn during one day. Aerobic metabolism refers to a series of chemical reactions that requires the presence of oxygen. In contrast, anaerobic metabolism means just the opposite– a series of chemical reactions that does not require the presence of oxygen. Energy is described as the capacity or ability to perform work. The most common unit of measure is the calorie.
To understand how the body fulfills the caloric energy demand during exercise without the presence of oxygen we must discuss your body’s complex fuel systems.
ATP-Adenosine Triphosphate
The energy source – Adenosine Triphosphate (ATP) is the most immediate source of chemical energy for muscular activity. If you suddenly jumped two feet into the air from a standing start, the energy source would be ATP. The energy available from ATP is very limited. If you ran 100 meters as fast as you could, you’d exhaust all of your ATP. The usefulness of the ATP system lies in the rapid availability of energy– rather than quantity. Only about 30 seconds of ATP is stored in the body. ATP is stored in most cells, but particularly in muscle cells. It is the most important anaerobic fuel source available. In fact, other forms of chemical energy, available from foods, must be transformed into ATP before they can be used by the muscle cells. ATP is the only source of fuel or energy the body accepts. Therefore, it is important to understand that all remaining fuel systems are simply resynthesizing and rebuilding ATP. There are two ways the body restores energy to ATP without the presence of oxygen.
Anaerobic Pathways
1. The first anaerobic method of ATP synthesis comes from a chemical compound called phosphocreatine (PC). Phosphocreatine is an energy rich compound similar to ATP. It is stored in the muscle. However, we’re more concerned with the other anaerobic system– lactic acid.
2. The lactic acid system is the second method used to replenish ATP during exercise.
THE LACTIC ACID SYSTEM
After the allocated supply of stored ATP is exhausted the body must find another fuel source in order for activity to continue. After the first 30 seconds the next available fuel source will come from the lactic acid system.
Technically, the lactic acid system, is known as anaerobic glycolysis. While glycolysis refers to the breakdown of sugar (carbohydrate), anaerobic glycolysis is the breakdown of (sugar) carbohydrate without oxygen. In this system the breakdown of sugar supplies the necessary energy required to resynthesize ATP. However, when carbohydrate is only partially broken down, one of the other end products is lactic acid. (Hence the name lactic acid system).
When a high level of lactic acid accumulates in the muscle and blood the result is temporary muscular fatigue and soreness. You have probably experienced this. It often occurs after extended anaerobic exercise. Activities such as weight training, tennis, basketball, football, etc. draw energy from sugar in the blood and muscles (glucose) to rebuild and resynthesize ATP.
The lactic acid system, like the ATP system, is extremely important because it provides a rapid supply of rebuilt ATP energy. Exercises that are performed at maximum rates between 1 and 3 minutes depend heavily upon the Lactic Acid System for ATP energy.
Daryl Conant, M.Ed