Lactate as Fuel, Not Waste: The Physiology of Running Fatigue | Dr. Michael Lindinger

For a hundred years, runners have blamed "lactic acid" for burning legs and fatigue. It's one of the most persistent myths in sport — and it's wrong.In this episode I talk with Dr. Michael Lindinger, exercise physiologist and former professor at the University of Guelph, who spent decades studying what actually happens to lactate and acid in working muscle. We get into what lactate really is (a fuel your muscles, heart, and brain burn — not a waste product), where the burning sensation actually comes from, why the soreness days after a marathon has nothing to do with lactate, and what "clearing lactate" really means for your training.If you've ever been told your legs were full of lactic acid, this conversation will change how you think about fatigue — and about what your interval sessions are actually building.Note: Dr. Lindinger works in the nutraceutical field; this is disclosed where supplements are discussed.----------------------------------------CHAPTERS 01:48 — Who is Dr. Michael Lindinger03:12 — What lactate actually is (and the 1930s myth)05:34 — The infusion study: lactate as fuel, not waste06:42 — Lactate as an oral supplement and the glucose-sparing effect08:44 — Lactate fuels the whole body — even the brain09:49 — A word from Pace Buddies10:22 — Where lactate is made, and why "anaerobic" is the wrong word12:37 — What really causes fatigue: potassium, sodium, phosphate13:32 — The phosphocreatine system: instant but short-lived16:15 — The burning sensation — cytokines, not lactate19:25 — Why the last 3K of a marathon burns (and it isn't lactate)20:27 — Post-race soreness: damage and inflammation, not lactate21:57 — What "clearing lactate" means when lactate rises23:41 — Fat burning, and why lactate is always being produced24:25 — How the whole body buffers and reuses lactate26:19 — Hitting the wall: running out of glucose27:32 — How fast the body clears lactate after hard efforts29:55 — Hydrogen ions, acidosis, and why lactate isn't "lactic acid"33:43 — Can you train lactate clearing?37:21 — Fast-twitch vs slow-twitch: where the burn happens39:03 — Do buffers work? Bicarbonate, beta-alanine 42:18 — The massage therapist myth43:21 — "Clearing lactate" in plain terms: what training really builds