Whether you are a triathlete, runner, skier, cyclist, or rower, as an endurance athlete you need accurate physiological data to guide and monitor your training by. Lactate threshold is one of the most commonly, and effectively, used performance markers used by many athletes and coaches.

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The energy required to move is supplied from the breakdown of adenosine triphosphate (ATP). The body can only store about 85 grams of ATP and would use it up very quickly if our bodies did not have a few ways of resynthesizing it. There are three energy systems that produce energy: ATP-PC (short, explosive movements), glycolytic (intermittent hard intervals) and aerobic (endurance exercise). Athletes most commonly attribute the intense burning felt during exhaustive bouts of exercise to the accumulation of lactate in the blood which is produced by the higher level of exercise intensity.

When you demand energy faster than your aerobic energy system can produce it, your glycolytic energy system picks up the slack. Even though the glycolytic energy system is often characterized as “anaerobic” (literally meaning without oxygen), it’s not that there’s no oxygen available, but rather that your aerobic system is going as fast as it can and you still need more energy.

The glycolytic system is fast but it’s less efficient and produces less energy, per unit of fuel burned, than the aerobic system. Your body has to clear the lactate from the blood and working muscles and process it back to useable fuels, and lactate threshold is the point at which production outstrips the clearing process and higher levels of blood lactate start to accumulate in the muscles.

Lactate threshold can be determined through lactate threshold testing, verified within your training program, and used to make you stronger and faster.

Why Lactate Threshold Matters

Your lactate threshold essentially defines the upper limit of your sustainable efforts in training and competition. Once you cross over and rely more heavily on your glycolytic system for energy, you’re exercising on borrowed time. The accumulation of blood lactate will hinder your muscles’ ability to contract, and you will be forced to slow down or stop.

The more work you can do before reaching lactate threshold, the better. If the pace you can hold at your lactate threshold is higher than the pace your competitor can hold at his or her lactate threshold, you go faster, reach the finish first, and win.

Being able to do more work at lactate threshold also means maintaining a lighter pace is even easier. While your main rivals are burning energy fast, riding at their limits, you can stay right with them and rely primarily on your aerobic system. This saves valuable energy for hard efforts later, like the run leg of a triathlon, a long climb to the finish line, or a sprint.