MYTHCONCEPTIONS

245: LACTIC ACID

The myth

When you exercise, lactic acid builds up in your muscles until it gives you “the burn” – pain and fatigue in the lungs and limbs that makes it impossible for you to carry on. The next day, the lactic acid lingers, causing further soreness and tiredness. That’s why, at the end of a day’s hard racing in the Tour de France, the first things cyclists do is to get onto a stationary bike and carry on pedalling while they give their interviews: they are flushing the lactate out of their legs so that they’ll be able to ride again tomorrow.

The “truth”

Lactic acid levels in the body certainly rise during exercise, as glucose is broken down to provide energy, but there is no evidence to show that lactates cause, or worsen, the burn. On the contrary, the acid produced is available as fuel to cells performing a variety of functions. Lactic acid doesn’t stop you – it helps you keep going. Day-after soreness has absolutely nothing to do with lactic acid. The acid does not “pool” in the muscles. A couple of hours after ceasing exercise, your lactic acid levels will be back to normal – and that’s true whether you carry out a rigorous warm-down, like the cyclists, or lie on a sun-lounger smoking a cheroot. Whether the stationary bikes do any good is another debate, but they can’t possibly have any effect on lactic acid levels. Biochemist Otto Meyerhof won a Nobel Prize in 1922 for experiments which established the theory that lactic acid build-up caused muscle fatigue. But his work was done on severed frog legs, electrically stimulated in an airtight jar. Scientists have known for decades that Meyerhof’s findings don’t apply to non-severed, human legs in real life conditions – and gradually, the world of sport is catching up.

Sources

www.bostonglobe.com/lifestyle/health-wellness/2014/04/20/ the-lactic-acid-myth/FskVYvZDXQ6k1tR0khM9UN/story.html; www. cyclingweekly.com/fitness/lactate-cycling-35412; www.getscience. com/biology-explained/science-fact-or-science-fiction-lactic-acidbuildup-causes-muscle-fatigue-and; www.nobelprize.org/prizes/medicine/1922/meyerhof/biographical/

Disclaimer

Exhausted by all this chemistry, we ache for your corrections, via the letters column please, of any errors.