第22页 | The Big Book of Endurance Training and Racing | 阅读 ‧ 电子书库

THE FULL SPECTRUM OF ENDURANCEGood overall health requires proper balancing of the nervous, muscular, skeletal, circulatory, digestive, lymphatic, hormonal, and all other systems. With this balance comes optimal health and the reduction or loss of common signs and symptoms—complaints that many athletes have, which are often considered normal in the course of training and competition but, in fact, are not. Fatigue, injury, allergies and asthma, frequent colds, and other complaints indicate an imbalance of health, often due to neglecting health and pushing fitness. These aspects of health are also the very systems that provide the activities to build fitness. Athletes who are fit but unhealthy not only have problems on various physical, chemical, and mental levels, but are unable to reach their athletic potential.Both states of fitness and health should be balanced with each other. Injuries, sickness, fatigue, and so on indicate an imbalance between fitness and health. While these problems are common, especially physical injuries, they are not normal in endurance sports the way they are in contact events such as football or hockey. It is unfortunate that most athletes are willing, consciously or not, to sacrifice health for greater fitness.

We don’t normally use only aerobic or anaerobic—or only fat or sugar—during training and competition. For example, the anaerobic system only has about three minutes of energy; and, to maintain fat burning for aerobic activity, sugar burning is also necessary. It’s mixture of these two fuels that provides us with optimal performance energy. When an endurance athlete fatigues in a race, it may be associated with the loss of available glucose necessary to sustain the conversion of fat to energy in the aerobic muscle fiber, or due to the inability to burn enough fat because of poor aerobic training.

Depending on your training, diet, stress regulation, and overall state of health, as much as 80 to 90 percent of total energy can be derived from fat. Unfortunately, too many athletes don’t burn sufficient amounts of fat, and because of this may never reach their athletic potential. One of the most important things you’ll learn in this book is how to increase energy needs through fat burning to generate optimal endurance. This includes improving aerobic speed—training the aerobic system to get faster.

As the aerobic system improves with proper training, fat burning increases and endurance improves too. This will be reflected in the RQ. For example, if an athlete today can run at a 150 heart rate and burn 50 percent fat and sugar, a month or two later he or she may improve so that, at the same 150 heart rate, now 60 percent of the energy comes from fat and 40 percent from sugar. Concurrent to these changes is a faster running, biking, swimming pace, or the same improvements in other activities.

Question: In one of your earlier books, you wrote that “aerobic is the ability of the body to use more fats and less sugar (glucose) for energy.” And that in events lasting for more than two hours, like the marathon, the aerobic energy used is more than 99 percent of the total energy. If all the above is true, then why do marathon runners become glycogen depleted and hit the wall? If most of their energy comes from fat, then they shouldn’t face that problem.Answer: The short answer is that too many marathoners do not fully develop their aerobic systems, and as a result they are unable to burn high amounts of fat for energy during a race. Instead, they must rely on more sugar for energy, often burning too much sugar during the race, including their sugar stores (glycogen), and hence becoming glycogen-depleted.Even in a properly trained athlete, burning fat is always accompanied by some sugar burning. A runner with a great aerobic system who is capable of burning high amounts of fat can still deplete his or her glycogen stores. This can occur if too much sugar or other refined carbohydrates are consumed before the race (increasing the hormone insulin, which can significantly reduce fat burning), by running the first part of the race too fast (which causes more sugar and less fat to be utilized), from excess pre-race stress, especially over several days (which also reduces fat burning), and for other reasons.Properly training the aerobic system results in a dramatic increase in fat burning not only during training, but during racing and all other times of the day and night. The more you develop your aerobic system, the more endurance you’ll have. You still use glucose/glycogen to help burn fat. Think of fat as the logs in the fire (a slow, long-term energy burn), and sugar as the kindling (quick, short term energy that helps fat burn).For marathon racing, it appears those with the most success run at a pace just faster than their maximum aerobic function. I base this on those who I’ve trained over thirty years and who are healthy and fit. An unhealthy or unfit athlete will have to compensate for their problem—by running with too high a heart rate, for example—thereby not achieving the best performance and possibly hitting the wall.

In properly trained athletes I’ve seen tremendous values for fat burning. The chart to the right was compiled on triathlete Mike Pigg.