Why am I so Sore?

Typically, I hit my marathon wall around mile 18. That’s when my legs feel like heavy wet logs en route to a paper mill’s pulp masher. For years I blamed my pain and stiffness on lactic acid.

Lactic acid. If you run, lift weights or simply know someone who does, then you are probably familiar with the term. Heck, even my cousin, who complains about strolling to the end of the driveway to fetch the newspaper, knows about lactic acid thanks to a marathon volunteer, who insisted he bring me over to the massage tent post race so I could have a professional “break up” the lactic acid that had built up during my 26.2-mile jaunt through the city.

Fast-forward four years to a day in May when I am interviewing a doctor who tells me there is no such thing as “lactic acid.”


Apparently, lactic acid does not exist as an acid in the body, rather doctors measure “lactate” in the blood to determine “lactic acid” concentration. So basically, if you are like me and have been blaming your stiffness following a marathon (or other long run) on a build up of lactic acid—-you’re wrong to do so. According to medical experts, the pain and stiffness you feel post-run is mainly due to muscle damage and not an accumulation of lactic acid or lactic acid crystals in the muscle.

And here’s another bubble-bursting fact: Doctors say you should think twice if you are blaming lactic acid for your fatigue. Some people believe (incorrectly) that lactate is responsible for acidifying the blood, which causes them to slow down. In fact, studies prove just the opposite. According to experts, lactate is an important fuel that is used by the muscles during prolonged exercise. Research shows that once lactate is released from the muscle it is converted in the liver to glucose, which is used as an energy source. Given this information doctors have concluded that rather than cause fatigue, lactate actually helps to delay a possible lowering of blood glucose concentration (a.k.a. hypoglycemia), which is associated with weakness and fatigue in a runner.

Long story short lactic acid is not the reason for your stiffness. So what is the culprit for delayed onset muscle soreness? According to doctors, the precise cause remains a mystery.

Were you aware of this lactic acid myth prior to reading this blog?

Michele Cheplic writes about red-hot celebrities in POP CULTURE, fiery topics in PARENTS, sizzling recipes in FOOD, calorie burning exercises in FITNESS, and hot new kid-friendly crafts in FUN. Check out all of her articles here.

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Michele Cheplic

About Michele Cheplic

Michele Cheplic was born and raised in Hilo, Hawaii, but now lives in Wisconsin. Michele graduated from the University of Wisconsin-Madison with a degree in Journalism. She spent the next ten years as a television anchor and reporter at various stations throughout the country (from the CBS affiliate in Honolulu to the NBC affiliate in Green Bay). She has won numerous honors including an Emmy Award and multiple Edward R. Murrow awards honoring outstanding achievements in broadcast journalism. In addition, she has received awards from the Aircraft Owners and Pilots Association for her reports on air travel and the Wisconsin Education Association Council for her stories on education. Michele has since left television to concentrate on being a mom and freelance writer.