The Science Behind FTP: How Your Body Produces Power

The science behind Functional Threshold Power (FTP) lies in your body’s ability to produce and sustain energy for cycling through a balance of aerobic and anaerobic systems. FTP represents the power output where your body can clear lactate from the blood as quickly as it produces it, allowing you to ride at a steady state without accumulating fatigue. Once you exceed FTP, lactate builds up, causing fatigue to set in quickly.

Your aerobic energy system is the primary contributor to FTP, relying on oxygen to break down carbohydrates and fats for sustained energy production. This is efficient but limited by your cardiovascular fitness and the capacity of your muscles to utilise oxygen. The anaerobic system, on the other hand, provides short bursts of high power by breaking down stored glycogen without oxygen, but it generates lactate as a by-product, which can impair muscle function when it accumulates.

Training to improve FTP involves enhancing your aerobic capacity (e.g., through endurance and threshold intervals) and increasing your lactate clearance ability. These adaptations come from physiological changes, such as increased mitochondrial density in your muscles, improved oxygen delivery from your cardiovascular system, and enhanced efficiency in using energy stores. By pushing your threshold higher, you can sustain more power for longer durations, making FTP a direct indicator of cycling performance and fitness.