1) Involve your muscle fibers with capillaries. The capillaries are the smallest blood vessels. Typically a number of capillaries surrounding each muscle fiber. They are the transportation system for the cell, bringing oxygen and fuel into, and waste carbon dioxide out. Long runs increase the number of capillaries per muscle fiber, which improves the efficiency of transport.
2) Carry oxygen with more myoglobin. Myoglobin in muscle cells have a similar function to hemoglobin in the blood - carries oxygen from the cell membrane to mitochondria. Long runs increase the amount of myoglobin in muscle fibers, so more oxygen can reach the mitochondria to produce energy.
3) Make mighty mitochondria. The mitochondria are the aerobic energy factories in cells. Long runs increase the number and size of mitochondria in muscle fibers. With more mitochondria, you can produce more energy aerobically, and maintain a race pace faster.
4) Increase aerobic enzyme activity. The enzymes in mitochondria accelerate the aerobic energy production. Long runs increase the activity of these enzymes, which improves the efficiency of the mitochondria. So you not only have more and bigger plants, but also more efficient.
5) Fill the tank with glycogen. Long runs teach your muscles to store more glycogen. Glycogen is the storage form of carbohydrates, and when you run long distances slow down. So how long runs lead to greater glycogen storage? Running long distances uses up the glycogen in the muscles. Our ancestors were at risk of being eaten when they ran out of glycogen. Fortunately, the depletion of glycogen stimulates the muscles to store more to prevent future shortages. Once the faster you run more glycogen you burn, run your long runs at a reasonable pace is the most efficient way to deplete your glycogen stores (and hence stimulate the muscles to store more) than jogging.
6) Burn more fat. Long runs not only increase your ability to store glycogen, they also allow your muscles to conserve glycogen by burning more fat. As you increase your endurance training, you rely more on fat than carbohydrates at a certain speed. As a result, your glycogen stores last longer. In a marathon, it means that the "wall" moves ever closer to the finish line.
7) Change the muscle fibers. The higher the percentage of slow twitch fibers in your muscles, the better your chances of success in the marathon. Well, for those not genetically endowed with a higher percentage of slow twitch muscle fibers, there is good news. Long runs give your fast twitch muscle fibers more characteristics of slow twitch. So, while sprinters will never be world-class marathoners, with sufficient training the fast-twitch fibers will gain some of the beneficial attributes of slow contraction.
by ( Runners)
