Green bodies: Lactic acid as a fuel source?

Your body can be greener? We don’t mean being a leprechaun. We mean being a better recycler. Read on…

For years, we’ve been told that lactic acid is a waste product that burns and shuts down muscles. It’s something athletes and fitness exercisers are urged to avoid. You’re told to work out just below your lactate threshold, where lactic acid begins to accumulate.

Well, some of that is correct, but it seems, most of it is wrong. 

The aerobic and anaerobic energy systems have long been thought to operate as separate and distinct systems. Lactic acid was considered the enemy of aerobic metabolism, with the power in sufficient accumulations to bring it to a halt. But we are smarter than that now…

 UC Berkley integrative biology professor George A. Brooks,  has been studying lactic acid since doing his doctoral dissertation on the subject in the ‘70s. Brooks says the idea that lactic acid is bad and to be avoided “was one of the classic mistakes in the history of science.”

“The understanding now is that muscle cells convert glucose to lactic acid,” Brooks explains. “The lactic acid is taken up and used as a fuel by mitochondria, the energy factories in muscle cells. Mitochondria even have a special transporter protein to move the substance into them.”

So, your ability to recycle lactic acid into the Krebs (or Citric Acid Cycle) reflects a great deal about your aerobic performance and capacity. Aerobic metabolism and anaerobic metabolism, in fact, operate side by side in the mitochondria. The heart, slow-twitch muscle fibers, and breathing muscles actually prefer lactate as a fuel during exercise. In short, lactic acid is a significant energy source, actually a good thing.

Hinting, or perhaps suggesting, how athletes can and are using this revelation, Professor Brooks said in a recent press release: “The world’s best athletes stay competitive by interval training. The intense exercise generates big lactate loads, and the body adapts by building up mitochondria to clear lactic acid quickly. If you use it up [as an energy source], it doesn’t accumulate.”

Too much lactic acid is still bad, however. It causes distress and fatigue during exercise, altering the local pH of the tissues and changing chemical reactions.  In extreme circumstances it can damage muscle cells.

So how can you learn to use lactic acid to your advantage? Stay tuned for the next lactate installment, coming to a Gait Guys Tumblr Blog near you….

Ivo and Shawn