Muscle experts started paying attention to lactic acid back at the beginning of the 20th century, when Dr. Otto Meyerhof studied muscle activity in frogs. Meyerhof cut a frog in half, put the bottom part in a jar, and used electrical shocks to make the muscles contract. This only worked for a short time, though, before the legs stopped jerking. Meyerhof found high levels of lactic acid in the muscles, and decided that the lactic acid must have made the muscles stop working [source: Kolata]. Meyerhof's scientific study of muscles won him the Nobel Prize in 1922.
W. H. Owles first wrote about the lactate threshold in 1930 and the idea of using the lactate threshold for sports training caught on by the mid-1960s [source: Viru]. For decades, scientists and coaches thought lactate was bad for muscles. Following Meyerhof's reasoning, experts saw lactate as a waste product that muscles made during the anaerobic breakdown of glucose. Not only was lactate a waste product, it was maligned as causing muscular acidosis. That is, since it is an acid, scientists thought that it prevented muscles from working very well. Coaches warned athletes to train below their lactate thresholds to keep from harming their performance and causing muscle aches. Many people still blame lactic acid for their sore muscles the day after a workout [source: Kravitz].
Lactate's reputation got a helping hand in the 1980s from biologist Dr. George Brooks. Brooks' hypothesis, called the Lactate Shuttle, says that muscles actually use lactate as a fuel during exercise. Brooks found that mitochondria (the parts of cells that make energy) even have a special protein that moves lactate inside them for use as a fuel [sources: Brooks, Kolata]. Also, lactate production happens in muscles at a time when lots of extra protons are floating around, making the muscles more acidic. Pyruvate molecules absorb some of those protons and turn into lactate, so lactate production actually makes the muscles less acidic, not more so [source: Kravitz]. Lactate did not deserve its reputation.
Lactate's redemption means that athletes can train at lactate threshold without fear of hurting their performance. In fact, lactate threshold training can help you increase the mitochondria in your muscles, so your muscles can use lactate better [source: Kolata].
So will all this science help your race times? Read on to learn the benefits of lactate threshold training.