Muscle Burn & Lactic Acid

Tl;Dr: Muscle burn isn’t caused by lactic acid, but it might be OK to think that anyway

When you exercise hard your muscles feel like they’re burning. Most people think of this as ‘Lactic Acid’, annnnndd… that’s wrong. Here’s a very good article, backed by this scholarly research. The short version is: Lactic Acid is generated by exercise, but it doesn’t (on it’s own) cause the burn or sense of fatigue and is actually used to fuel muscle activity. Also… your body consumes it very quickly, within an hour of when you exercise. So all that I’m working out all the lactic acid buildup in my muscles? It’s not what you think it is.

The back story is kind of amazing – people have been thinking that muscle activity causes lactic acid build up since the very early 1800s (thank you Jöns Jacob Berzelius). So there’s been plenty of time for this to become embedded lore.

Some time around 2013 folks started looking more closely as far as I can tell:

• The burning sensation is caused by acid, just not lactic acid
• It seems to be a combination of Hydrogen Ions (H+), Lactate, and ATP (H+ is an acid all on it’s own)
• The precise cause of the fatigue sensation is still a topic of research
• And weirdly – Baking soda (a base) seems to enhance athletic performance by acting as a buffer (I haven’t looked into this yet)

Lactic Acid is also not what causes Delayed Onset Muscle Soreness. That continues to be related to micro-tears in the muscle tissue.

But what is true is that: Muscles burn when used, the burn is caused (in part) by acid (H+). So while it’s not really correct to say Lactic Acid is building up and causing the burn, it’s pretty damn close and good enough for government work.

Just don’t get fooled by products claiming to remove lactic acide from your muscles – that’s BS.