第156页 | The Big Book of Endurance Training and Racing

Measuring Fat and Sugar Burning

This mix of fuels can be easily measured in a person with a gas analyzer, which measures the amount of oxygen a person takes into his or her body and the amount of carbon dioxide eliminated. The ratio of carbon dioxide to oxygen is called the respiratory quotient (RQ), and from it is determined the percentage of fat and sugar used for energy. A lower RQ number corresponds to greater fat burning and a higher level of aerobic function. I do not necessarily recommend most people have an RQ test because it is not readily available and many coaches and healthcare professionals don’t relate the findings to endurance training. And the protocol used by most people is the same one used to measure VO₂max, which is an unnatural test. However, it is useful for you to understand the RQ concept in order to better understand the physiology of how all the information in this book will improve your endurance.

In addition to increased fat burning and better aerobic function for significant improvement in fitness, it’s common to see better health associated with more utilization of fat as a fuel. Following is a list of some of my patient’s RQ numbers at rest and their symptoms. Take away the patient initials and the chart could really be one person who progresses on the program outlined in this book. In general, the less sugar and more fat burning at any level of intensity, the more healthy and fit the individual.

Dietary carbohydrates are also important nutrients for our endurance and overall health. But just like the need to consume high-quality fat, the same is true for carbohydrates. We should consume them in their natural form and avoid processed/refined carbohydrates, which can impair our endurance because it can reduce fat burning.

Perhaps just as important as the food we eat is the ability to properly digest and absorb these nutrients. Without proper digestion of macronutrients to make glucose, fat, and amino acids available for absorption, and the breakdown of foods so micronutrients and phytonutrients are available for absorption, imbalances can occur even with the ideal diet.