Is a technique employed by some endurance athletes to increase their storage of muscle glycogen?
Carbohydrate loading is a strategy involving changes to training and nutrition that can maximise muscle glycogen (carbohydrate) stores prior to endurance competition. The technique was originally developed in the late 1960's and typically involved a 3-4 day 'depletion phase' and a 3-4 day 'loading phase'. Ongoing research has allowed the method to be refined so that modern day carbohydrate loading is now more manageable for athletes.
Runners in general need as much fuel as possible to help them get through their running routines. As a result, the best breakfast for them is to have a meal high in fiber and carbohydrates. These nutrients are deposited in the body as energy reserves (glucose and glycogen) which can prove useful in bettering the body's performance during endurance training.
If the athlete had a fit rich and a poor carbohydrate diet, it would mean that they would have lower muscle glycogen content and a higher rate of fat oxidisation during exercise, when compared with a high carbohydrate low fat diet. The whole effect of such a diet could potentially be a sparing of muscle glycogen, and because muscle glycogen storage is paired up with endurance performance, it is possible that adaptation to a high fat diet could potentially enhance endurance performance. Therefor the athlete could afford to eat fatty things in their diet and be able to use the energy it gives to good use. The athlete would have to perform a lot of endurance exercise so that it does not hinder the performance.
Why do athletes who compete in long-distance events often eat foods high in carbohydrates the day or two before their event?
Carbohydrates are able to provide more energy (ATP) than other nutrients. The liver and muscles can store a form of sugar called glycogen. Glycogen is like energy on demand during exercise. By eating lots of carbohydrates before running long distance, athletes make sure that their glycogen stores are as full as possible. This way the very important energy that glycogen provides the athlete will hopefully not run out too early in the event.
All together the avg. human can store approx. 500-600g of glycogen. Skeletal muscle holds twice that of the liver,, so approx. 200g for the liver and 400g for the muscle. In endurance type sports like cycling at 70%vo2max this equates to about 2 - 2.5hrs of exercise before glycogen depletion but this varies from individual to individual based on how well trained the athlete and the training protocols used. It is interesting to note that the body places a pref on liver glycogen over muscle glycogen during prolonged exercise and that fasted exercising increases overall glycogen storage capacity. whether in the muscle alone or liver or both is uncertain.
There is debate as to this answer. It is also hard to answer because glycogen is not stored evenly throughout the body, it is stored in the liver and the muscle tissue. Assuming a person has been eating plenty of food, namely carbs, and the glycogen levels are full most texts report the liver being able to hold 70-100 grams of glycogen and the muscles holding 200-400 grams of glycogen. The more muscles someone has and the more trained they are (athletes, etc) the more glycogen they can hold. If we say an average male is 80 kg and an average male has 350 grams of glycogen, then you have about 4.5 grams of glycogen per kg, but again it is not stored evenly so it is an unusual way of framing the question.
What skeletal muscle fibers that are used for endurance activities have a large quantity of a-creatine-phosphate b-glycogen c-mitochondria d-anaerobic enzymes c-stored APT?
Liver glycogen has low glycogenin content as compared to muscle glycogen.. liver glycogen responds to glucagon but muscle glycogen responds to catecholamines.. liver glycogen is used for the maintenance of blood glucose levels, but muscle glycogen is used for the supply of energy to the muscles liver glycogen can be completely broken down to glucose because of the presence of glucose 6 phosphatase, which does not occur in the muscles