It is defensible to say that no molecule has as much controversy and misunderstanding in all of exercise physiology and sports than lactate. We start with the basics:
- Where do lactate and lactic acid come from - how is it produced?
- What happens to lactate / lactic acid once it is produced - what is it’s fate?
- We go through some common statements and talk about what’s correct and what is not:
- "Lactic acid build up is what causes muscle burn."
- "Lactic acid stays in muscle and causes soreness."
- "Doing some sort of stretching, massage, or exercise will ‘wash out’ lactic acid from a prior training session."
- "Now the big one: lactic acid build up causes fatigue."
- The ‘lactate threshold’ has had many definitions. These are as disparate as the onset of blood lactic acidosis to the maximal lactate steady state - very different exercise intensities with regard to endurance performance. Dr. Gladden gives us a brief history and explanation.
- Gas exchange is a different topic but many attempts have been made to correlate gas exchange thresholds with lactate thresholds and, ultimately, performance capacity thresholds. This is a big topic area, but Dr. Gladden briefly relates gas exchange concepts/thresholds to definitions of lactate thresholds.
- We learn the answer to: Is it necessary to exercise at or above the lactate threshold (whichever definition one uses) to increase it or can sub-LT exercise improve the LT?
- There is controversy over the source of H+ (hydrogen ions; protons) in exercise ‘acidosis’. Does it come from lactic acid, splitting of ATP, or some other source?
- While the maximal lactate steady state is at least a rough idea of the work load that can be sustained for a ‘long time’, ultra marathons last 4-5 hours on the short side and 24-36 hours in the longer events. How long can the workload of MLSS really be sustained even if every other aspect of performance (hydration, core temp, etc.) could be maintained perfectly?
- If lactate / lactic acid doesn’t cause fatigue and the MLSS is not sustainable for ultra marathon distances, to what extent is lactate / lactic acid relevant for ultra marathon training or performance?
We wrap up with two questions as take-home points: 1. What is the biggest misunderstanding that endurance athletes have about lactate / lactic acid? And, what is correct? 2. What advice does Dr. Gladden give to an ultra marathon athlete interested in their LT to apply to their training for ultra marathons?
