Everything You Know About Lactic Acid Is Wrong

Everything You Know About Lactic Acid Is Wrong

For a semi-serious athlete, Jeremy Rosenberg is not unusual. The Los Angeles-based book editor is a weekend warrior on the city’s soccer fields, but says he pays for it after most games.

“A couple of hours after I play I feel like what I imagine a whirling dervish does: A post-ecstatic mental state combined with being totally physically drained,” says Rosenberg. “As long as I’m playing, I feel great. But stopping means soreness.”

Rosenberg and his fellow players don’t pretend to be physical therapists or exercise scientists, but they confidently throw around the same term to explain their aching muscles: Lactic acid buildup.

Sounds familiar, right? Only one problem. Rosenberg, many trainers, and even some physicians are making the same mistake — lactic acid isn’t what most people think it is.

 

What Is Lactic Acid?

“One of the long-standing myths in exercise science and popular culture is that lactic acid causes fatigue,” explains Lance Dalleck, an assistant professor of exercise and sport science at Western State Colorado University. But the body doesn’t produce lactic acid, not even during intense exercise.

“Lactic acid only exists in sour milk,” says Dalleck, “and blood and sour milk have markedly different mediums.”

 

What People Actually Mean by “Lactic Acid Buildup”

That’s right: when most people talk about “lactic acid buildup,” they are actually talking about lactate, whether they realize it or not — but lactate doesn’t do what they think it does.

It’s not responsible for the burn you feel in your legs after running intervals, nor is it responsible for the soreness you may feel up to 48 hours after a tough workout, as many believe. Indeed, it’s not a waste product of exercise at all.

On the contrary, lactate can help to delay fatigue, and can even serve as a fuel for your muscles, says Dalleck.

 

lactic acid- woman with sore leg

How Lactate Got Confused with Lactic Acid

The whole misunderstanding dates back to a study published in 1923 by two British scientists, Otto Meyerhoff and Archibald V. Hill. In their Nobel-Prize winning research investigating the energy capabilities of carbohydrate metabolism in skeletal muscle, they suggested that lactic acid is produced in humans as a side reaction to glycolysis (the breakdown of glucose to fuel muscle activity).

And that’s essentially how it’s been explained ever since: Lactic acid is a sort of residue from your muscles burning fuel, and its buildup is what causes the burn and ache athletes commonly experience during and after intense effort. After all, acid burns, right?

What more recent studies have determined fairly conclusively is that while lactate — not lactic acid — coincides with “acidosis” in muscles, it’s not the cause.

 

So How Does Lactic Acid Buildup Affect Muscles?

First, we agreed to call it “lactate.”

Second, a quick review of how the body uses and produces energy is probably in order. There are two primary means by which physical activity is powered: aerobic metabolism, which requires oxygen, and anaerobic metabolism, which doesn’t. Both produce ATP, the body’s primary unit of energy, but anaerobic metabolism does it a lot faster, which is why it’s the primary energy system for high-intensity exercise.

But as a consequence, anaerobic metabolism also produces waste products — including hydrogen ions — faster than the body can mop them up. “It’s the increase in these ions that causes acidification, known as acidosis, and that does burn,” says Dalleck.

That’s why you likely start to “feel the burn” quickly during sprints and high intensity interval training (and even weightlifting) compared to, say, jogging. It’s also why you can’t sustain the former activities as long.

 

Does Lactate Cause Muscle Soreness?

Along with acidosis, lactate is also frequently blamed for delayed onset muscle soreness (DOMS), which can occur as soon as six hours after exercise, and typically peaks 48 hours afterward. The blame is misplaced here as well, as DOMS is caused by micro-tears in muscle, not the buildup of lactate. Still, there are several steps you can take to ease the ache.

 

lactic acid- taking pills

• Pop some ibuprofen (maybe)

The soreness you feel after a tough workout is the result of swelling and inflammation caused by the micro tears mentioned earlier. Popping Ibuprofen, which is an anti-inflammatory, can significantly reduce the pain, according to a study by Greek researchers in the Journal of Strength and Conditioning Research.

But that relief may come at a price. An ever-growing body of research has also linked NSAIDs (including ibuprofen) to everything from cardiovascular issues and intestinal dysfunction to suppressed protein synthesis post-exercise. Occasionally taking a couple capsules for muscle soreness is probably just fine — but give some serious thought before using it regularly.

• Take tart cherry extract

Doing so can help reduce DOMS not only after a tough endurance workout, but also after intense resistance training, according to two separate studies (here and here) at Texas A&M University.

Both studies supported the results of previous research, showing that tart cherries can help reduce muscle breakdown and inflammation, thereby reducing soreness.

self massage- lactic acid

• Give yourself a massage

Using a foam roller to knead your muscles post-workout can significantly reduce DOMS, according to a recent study in the International Journal of Sports Physical Therapy. Give each major muscle group at least five rolls, starting with your calves and working your way up your body. Spend extra time on sore spots.

• Wear compression gear

People who wear compression garments after their workout experience less soreness and faster muscle recovery than people who wear a more traditional gym outfit, like a t-shirt and shorts, according to a recent study in the Journal of Sports Science and Medicine.

The reason: By compressing the muscle, such garments help reduce swelling and pressure.

About

Ben Sullivan is science writer based in Los Angeles. He is also founder of ScienceBlog.com, a blogging network for researchers and science aficionados. He can be reached at bensullivan@gmail.com.