Energy System - Lactic Acid
Lactic acid – officially known as lactate, is a product of anaerobic glycolysis (using sugar as energy). It is commonly thought of as a negative byproduct that causes muscle burn and muscle failure. It is now known that it is quite the opposite. It is now thought that hydrogen (another product of metabolism) is related to the muscle burn due to its influence on local pH levels. Through a process known as the Cori cycle, lactate can be transported to the liver and quite easily be converted back into glucose!
Why do we care about lactate? Knowing that lactate is actually a good thing is a step in the right direction to help us improve our understanding of physiology. In exercise prescription, we can use lactate levels to help us determine intensity levels. We can train our ability to buffer, clear out, and use lactate more quickly. Most 5-10k foot races will allow athletes to sustain their lactate threshold and even above, this is likely not the case for longer races.
We use lactate threshold training to increase our high intensity endurance performance. This is a pace sub-maximal to an athletes VO2max (50-80%VO2max). It is essentially the highest sustainable output level. When we train at our lactate threshold we improve our ability to produce energy and clear negative metabolites. We can use pace/tempo training to improve our ability to sustain effort at that intensity. We can also improve our lactate threshold trough interval training, repeated sprints, and Fartlek training.
The best ways to stay at the lactate threshold intensity is using either running or stationary cardio equipment (row erg, ski erg, cycle). If you have access, you can test your blood lactate levels, aim for above 2.0mmol/L initially. If you exceed 4.0mmol/L then you will likely not be able to sustain the effort. There will be an intensity above the lactate threshold where blood lactate will accumulate very rapidly due to an imbalance of production and clearance.
Always begin with a warm up and end with a cool down, this type of training is mentally and physically demanding.