Sooner or later, as an endurance athlete, you will come across a discussion of ‘lactate’, whether you are also an exercise physiologist or not. Blood lactate concentrations are routinely measured in endurance athletes, and so-called ‘lactate thresholds’ are used to inform training decisions. Some athletes and coaches even spot-test blood lactate concentrations during exercise to regulate intensity during training. And this is becoming more popular than ever – word on the street is in Kona this year, just about every athlete stopped to take lactate. Of course, this has been massively popularized by the Norwegian program's success, and rightly so! They are doing some amazing things!

However, I believe many people misunderstand what lactate is and isn’t and what blood lactate responses to exercise can and can’t tell you. So, in this blog, I will briefly summarise some of the fundamental physiology of lactate metabolism. Brace yourself for some...