Most people firmly believe that lactate/lactic acid is the cause of muscle fatigue, “burning” and tying up. They’ll purchase supplements believing the products can reduce lactic acid, and they’ll make dietary changes for the same reasons. But lactic acid’s relationship to muscle fatigue is terribly misunderstood. Lactic acid isn’t the enemy.
Muscles And Energy
Muscles produce lactic acid continuously. It’s generated during the breakdown of glucose as an energy source. If the horse is moving slowly, most of the lactate is further broken down to pyruvate and goes into aerobic energy pathways. However, as the horse moves faster and needs to produce energy quickly to keep up with the demands, the aerobic pathways are too slow and more energy is generated anaerobically, producing lactate.
Lactate isn’t a “waste” product or a toxin. It’s beneficial. Lactate is used by the liver and by muscle cells that aren’t being worked as hard. Lactate is also a buffer, a way that muscle cells can carry harmful acidity out of the cells. This is because the lactate molecule binds the acidifying hydrogen ions and carries them into the circulation.
People who have been used to thinking of lactate as harmful have trouble accepting this concept, but many studies have failed to find any relationship between lactate levels after exercise and poor performance. In fact, it’s often found that the superior-performing horses are those with the highest lactate levels after exercise.
A similar association between high lactate production and superior performance has been found in human athletes.
What this all boils down to is that blood lactate after exercise is nothing more than an indicator of how hard/fast the horse worked. It’s not connected to tying up or muscle damage. Instead of being harmful, lactate is actually a source of energy and reduces the acidity inside hard working cells by carrying the hydrogen ions out of the cell. High blood lactate is associated with superior performance, not fatigue. Next time you see advertising for a supplement or grain that claims to make your horse work harder or longer by lowering lactate, pass it up.