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The Lactic Acid Myth
Lactic acid is not the enemy. It does not cause delayed muscle soreness. Jason grew up in the 80s believing it did, and he was wrong, and he will tell you about it.
The popular understanding of lactic acid goes like this: you exercise hard, lactic acid builds up, lactic acid causes the burning feeling during exercise, lactic acid causes soreness the next day, and the goal of cool-downs and recovery work is to “flush it out.”
This is mostly wrong.
During the BFR episode, Jason admitted he spent decades believing that “the lactic acid will just eat you alive” and that all of sports medicine existed to combat it. Kathy explained the actual picture: the metabolites that accumulate during intense exercise (lactate, hydrogen ions, phosphate) are byproducts of energy production — not villains. In the context of blood flow restriction training, trapping these metabolites intentionally inside a muscle produces beneficial anabolic hormone responses. The body treats the metabolic stress as a signal to grow.
Delayed onset muscle soreness (DOMS), the stiffness 24 to 48 hours after exercise, is caused by muscle damage from mechanical stress, particularly eccentric loading — not by lactic acid. Lactic acid clears from muscle tissue within about an hour of stopping exercise. Kathy is tired of people blaming it.
First seen in Blood Flow Restriction Training: Science, Safety & Gains.