What we now know about blood lactate and exercise

The whole world has been talking about Michael Phelps since he won eight swimming gold medals and broke seven world records at the Beijing Olympics. While most of that talk focuses on his jaw-dropping performances, some of it centers on the much more mundane topic of his lactic acid levels. Apparently testing has determined that Phelps has significantly lower levels of blood lactate (lactate being the correct term for lactic acid) after intense swimming than do other elite swimmers. 

So are Phelps’s unusually low blood lactate levels the key to his unparalleled success? Maybe partly, but not for the reasons most people have been suggesting. Some have been saying that while higher blood lactate levels cause his rivals to slow down, Phelps’s low blood lactate levels allow him to keep chugging along and finish stronger. Others insist that his lower blood lactate levels leave his muscles less sore and therefore allow him to recover more quickly after workouts and races than others with higher blood lactate levels. These common explanations, however, are actually based on old ideas and misconceptions about the effects of blood lactate during exercise.

Instead, scientists have recently learned that lactate does not cause fatigue. Nor does it cause post-exercise muscle soreness, as blood lactate levels return to normal within an hour after exercise has ended while muscle soreness doesn’t peak until one to three days later. So what does lactate really do? Here’s what we now know about lactate and exercise—and how it all applies to the Phelps phenomenon.   

Lactate doesn’t hamper performance—it fuels performance.

During moderate to intense exercise, the muscles get most of their energy from two forms of carbohydrate: blood glucose and muscle glycogen. The muscles are able to burn carbs at a slow rate with oxygen (aerobically) and at a quicker rate without oxygen (anaerobically). Lactate is produced during the anaerobic breakdown of carbs. But instead of slowing the muscles down as was previously thought, the lactate that is produced during intense exercise can be immediately utilized by the muscle cells to continue to fuel exercise. Ultimately, if the muscles cannot use the lactate as fast as it is being created, it will begin to leak out of the muscle cells and into the bloodstream, where it will travel to other tissues to be used as energy or it will go to the liver, which can convert it back into carbohydrate fuel and ship it back to the muscles to use. So whether it is used immediately by the muscles or circulated throughout the body via the blood, lactate serves as a primary source of fuel during exercise.  

Phelps’s low blood lactate levels are a sign of efficiency.

Knowing what we now know about the role lactate plays during exercise, there’s a better way to explain Phelps’s low blood lactate levels. It’s not that he doesn’t produce a lot of lactate in the first place, but that he has a superior ability to utilize the lactate his incredibly hard-working muscles create before it exits the muscle cells and enters into the bloodstream. Any athlete’s ability to use lactate as fuel is determined by factors that include the concentration of mitochondria within the muscle cells and the concentration of protein transporters that deliver lactate to the mitochondria. Proper training certainly enhances these factors, but they are also influenced by genes. Phelps is probably gifted with very high concentrations of both mitochondria and lactate transporter proteins that allow his muscle cells to use most of the lactate they produce before it leaks into the bloodstream.

The faster you can process lactate, the longer you can exercise at a high intensity.

The bottom line is that Phelps’s unusually high capacity to use lactate as fuel enables him to convert more energy into forward motion when he swims, so he wins a lot of races. Would you like to be a little more like Michael Phelps? While you can’t change your genes, you can boost your ability to use lactate for fuel by taking ARX. Using ARX won’t make you a gold medalist, but it may take you one step closer.