Endurance plays a major role in many athletic activities. Without endurance training, many athletes would not be able to compete in their respective sports. Endurance training involves low resistance and high repetitions, but what exactly does this do to your body and how does it do it?
For starters, endurance training increases the level of certain aerobic enzymes, which are needed for the breakdown of fuels to produce energy. Enzymes are proteins that speed up metabolic reactions; they release and transfer energy. Enzymes are influenced by many factors:
1) Temperature- activity is increased when the muscles are warm, therefore warming up before the actual activity is very important
2) Acidity- lower Ph levels reduces enzyme activity, leading to fatigue
3) Fuel- enzymes work faster when they have more fuel
The faster the enzyme can breakdown your body's fuel, the faster you will receive energy.
Training also increases the number and size of the mitochondria. Mitochondria are cellular powerhouses that produce energy aerobically. All oxidative energy production takes place in the mitochondria. Oxygen is the key to endurance training, so the mitochondria are very important. Oxygen is needed to breakdown carbohydrates and fats, which provide energy. Dr. John Holloszy conducted an experiment to prove the importance of the mitochondria in endurance training. He had two groups of rats. One group was trained and eventually could exercise continually for four to eight hours. The untrained rats became tired after thirty minutes of exercise. Holloszy found a fifty to sixty percent increase in the mitochondrial protein and a twofold increase in oxygen consumption in the muscles of the trained rats. This also led to the conclusion that endurance-trained muscle fibers are better able to burn fat as a source of energy. Endurance training causes only limited gain in muscles. Muscles not involved in training may actually lose strength. However, there may be an increase in myofibrils, but no significant increase in muscle fibers. Evidence has shown that fast-twitch fibers take on oxidative capabilities and assume the properties of slow-twitch fibers. Long distance runners have as much as eighty- percent slow-twitch fibers. Training also causes an increase in the ability of fast-twitch fibers to utilize oxygen.
Endurance training also affects cardiac performance. The...