Myths About What Causes Muscle Soreness You Probably Still Believe

Lactic Acid Muscle Soreness Myths

If you’re an athlete, chances are you’ve experienced your fair share of agonizing muscle soreness, probably more often than you would prefer.

You’re also likely to have heard trainers and gym buddies confidently explaining that the root cause of your muscle soreness woes is the buildup of lactic acid while you train.

But is there any truth and scientific evidence to back this theory? Or is it just an explanation repeated so frequently that it gradually became accepted as fact without question.

And if lactic acid isn’t what causes soreness, what is?

This article breaks down the known theories of what causes muscle soreness and the ways you can reduce its effects to get you through those painful days after a challenging workout.

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The Six Theories About What Causes Muscle Soreness

There are six prominent theories about the which underlying biological mechanisms cause muscle soreness. Each with varying degrees of credibility and evidence backing them:

  1. Lactic Acid
  2. Muscle Spasm
  3. Connective Tissue Damage
  4. Muscle Tissue Damage
  5. Inflammation
  6. Enzyme Efflux

The lactic acid hypothesis, of course, is the most well-known. Surprisingly, it’s also the theory with the least amount of evidence to support it. But that hasn’t stopped it from remaining as the go-to explanation for the cause of muscle soreness for the average athlete and trainer.

Let’s break down the origin of the lactic acid theory, and where it ended up going sideways.

The Myth of Lactic Acid

The original belief stemmed from the observation of elevated levels of lactic acid during intense exercise. Combine that with it being closely related to the process causing you to experience “the burn” during exercise, and it’s not surprising that the dots were connected to lactic acid being the likely candidate for causing soreness after training.

Lactic Acid vs Lactate
Lactic Acid vs Lactate

The first myth about lactic acid is that it actually exists in the human body. Believe it or not, humans don’t produce lactic acid. We produce lactate. 

During glycolysis, your body produces lactate, ATP, and water. Then when ATP breaks down through a process called hydrolysis, it releases hydrogen ions that create the characteristic burn you feel during exercise. 

This temporary experience is called lactic acidosis. And while chemically not the same as lactic acid, shortening down the term lactic acidosis is likely the origin of calling lactate, lactic acid.

It may be a proton short of lactic acid, but the terms find themselves used interchangeably and commonly meant to refer to lactate. Semantics aside, most people know it, and refer to it, as “lactic acid” – so we won’t split hairs.

The Debunked Lactate (Lactic Acid) Relationship

For how prominent the theory of lactate’s involvement in muscle soreness is, a study conducted way back in the 1980s largely debunked the theory.

During the study, they split groups of participants to perform two different exercises. One exercise would produce high blood-lactate concentrations (level surface running), and the other would not (decline surface running.) 

Interestingly, the study found that muscle soreness was not prevalent in the group with high blood-lactate concentrations. The group with low blood-lactate concentrations surprisingly still experienced significant muscle soreness despite having low lactate buildup.

The results showed no relationship indicating the presence of lactate as a direct factor for muscle soreness or delayed onset muscle soreness (DOMS.) 

What Causes Muscle Soreness?

The primary cause of muscle soreness is the structural damage of muscle tissues from intense, eccentric, or unfamiliar exercise.

We can feel the effects of muscle soreness. We can also pretty reliably induce muscle soreness to test its effects. But the truth is, while many hypotheses exist, the exact “pathophysiological pathways” for what causes muscle soreness still remain unknown.

Likely, the combination of many factors within the six different prevailing theories creates the overall feeling associated with muscle soreness.

So when it comes to figuring out what reduces muscle soreness in practice, the more effective methods reduce the symptoms associated with many of the six theories for the cause of soreness.

However, the more understanding we gain of the direct cause of muscle soreness, the methods used to prevent and treat it will also significantly improve in the future.

Best Ways to Reduce Muscle Soreness

Even though science is yet to discover the biological pathways that cause muscle soreness, there are still practices observed to help alleviate soreness and DOMS.

At the end of the day, if something helps, that’s still concrete evidence of its effectiveness, regardless of if we don’t understand precisely why it’s working. 

Here are the top practices that athletes swear by:

1.) Foam Rolling

Foam rolling has long been instinctively used by athletes to reduce the onset of muscle soreness and even temporarily relieve pain when you’re already sore. And the research shows similar results.

Foam rolling works as a form of self-myofascial release (SMR.) SMR has a few different reasons why it may help reduce muscle soreness. 

First, it activates the triggers in your muscles that cause them to expand and contract. When this happens, it gives the tissue the opportunity to stretch and re-align.

Secondly, SMR helps improve circulation to the targeted muscle groups. Improved circulation helps re-oxygenate depleted tissues, transport metabolic waste out, and reduce the inflammation response. 

Self-myofascial release also helps reduce your pain perception. Which prevention aside, is typically what you’re looking for once the damage is already done and you find yourself hobbling around after a challenging workout.

If you really want to amplify the soreness-reducing effects of foam rolling, adding vibration therapy through a vibrating foam roller further reduces pain perception and improves circulation.

2.) Percussive Therapy Massage Guns

Massage guns fall under the same logic of self-myofascial release as foam rollers but isolate the treatment to a much smaller area with incredibly higher mechanical force.

The additional force and more concentrated pressure make massage guns incredibly effective at targeting specific trigger points compared to foam rollers’ broader and more distributed surface area.

Additionally, percussive therapy also includes the same positive effects of vibration therapy, which provides another pathway to improving circulation and blood flow throughout your muscle tissues.

Check out our ultimate guide to percussive therapy if you want to dive into the details and all of the benefits that come with using massage guns.

3.) Cold Immersion Therapy (Ice Baths and Cold Showers)

Muscle soreness is considered a form of minor exercise-induced injury. And in second place, only topped by rest in the RICE method for treating injury is ice.

Cold immersion therapy like ice baths and cold showers takes the concept of using ice as a local treatment and expands its use across more surface area of the body.

The main pathways cold exposure affects for muscle soreness are reducing inflammation and an entire cascade of positive mechanisms that jumpstart your recovery. 

Its long list of benefits coincides with many of the six theories for the cause of muscle soreness, which makes it an excellent practice for reducing its effects.  

4.) Sauna and Heat Therapy

Like self-myofascial release and cold immersion, heat therapy also helps improve circulation, transporting oxygen-rich blood and nutrients back into depleted muscles and transporting waste products out.

However, an even more powerful benefit from sauna use is the increased production of heat shock proteins. Heat shock proteins help signal which amino acids are needed to repair the muscles damaged during exercise. They also ensure that the proteins used in new muscle tissue fold correctly throughout the repair process.

Because minor muscle damage during exercise is the root cause of sore muscles, an efficient repair process is one of the best ways to ensure a reduced or shortened period of time experiencing the effects of soreness.

5.) Pneumatic Compression Boots

Pneumatic compression technology originated as a medical device to improve blood and lymph circulation for patients with diminished circulation. 

Since circulation improvements also have fantastic benefits for athletes, the technology quickly shifted over to be applied for exercise as well.

Most pneumatic compression boots like the NormaTec Legs use sequential pulse technology that mimics the natural way your body pumps blood throughout your body. So instead of just static compression, like compression garments that have a less pronounced effect, you see a significant improvement in re-oxygenation and waste transport after exercise.

Aside from the physical benefits of compression boots, they feel fantastic when you use them. And for a pair of sore legs after a brutal workout, sometimes that’s all you want.

Final Thoughts:

Even though the exact biological reasons why muscle soreness occurs are still a mystery. It is still, unfortunately, an unavoidable experience for most athletes.

But luckily, even if we don’t understand precisely what causes it, there’s still a significant body of research around the methods you can use to help alleviate its effects.

Many of the tools and protocols we talk about here on Mobility Athlete revolve around maximizing recovery, reducing inflammation, improving range of motion, and reducing pain. So as a by-product, they also help manage soreness after training.

So don’t forget to subscribe to the Mobility Athlete newsletter if you’d like to get more tips and tools delivered directly to your inbox to keep you on track with your mobility and workout recovery goals.

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