Читать книгу HIIT Your Limit. High-Intensity Interval Training for Fat Loss, Cardio, and Full Body Health онлайн

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Let’s break down the term, mitochondrial respiration. First, as you may recall from your earlier reading in the book, mitochondria are small, bean-shaped organelles in your cells. They are the energy factories that completely disassemble fats and carbohydrates, and with the help of oxygen, produce the ATP needed for sustained aerobic exercise (and life). The term “respiration” refers simply to the use of oxygen in the aerobic energy system.

My students often ask me why our bodies don’t exclusively use fats for fuel in mitochondrial respiration. They pose their question like this: we store so much more fat than carbohydrates, so why don’t we use 100% fat for fuel for exercise? Here’s my answer: during exercise, our need for ATP is massive; we need it to keep us moving. And, as discussed above, the source of ATP is fats and carbohydrates. Our cells break down fats for fuel much more slowly than they break down carbohydrates, so, as our need for energy increases during high-intensity workouts such as HIIT, our muscle cells call on carbohydrates to come to the rescue. We are always burning fats during exercise, but as our intensity increases we use quite a bit of carbohydrates too, because they can produce ATP quite fast. The great news is, the more regularly you do HIIT workouts, the faster your body learns how to burn fat to make ATP. So, one of the greatest benefits of regular aerobic exercise is that it trains your muscles to become very efficient fat-burning engines.