Why is pacing critical in running events with respect to lactic acid?

• A. Starting too fast reduces lactic acid
• B. Starting too fast increases lactic acid, impacting performance later
• C. Lactic acid is irrelevant
• D. Pacing does not affect fatigue

Answer: (B)

The main idea here is how lactate builds up with effort and how that affects how long you can keep a given pace. If you start too fast, you push into a mode where the body relies more on anaerobic glycolysis, producing lactate quickly. That rapid lactate rise brings more hydrogen ions, which acidify the muscle and interfere with the enzymes and calcium handling needed for fast, smooth contractions. The result is earlier fatigue and a noticeable drop in speed later in the race as you struggle to sustain the initial surge. Pacing helps keep effort near or below the level where lactate production can be balanced by its clearance, letting you maintain a steadier pace to the end. Lactic acid isn’t irrelevant here; it’s a signal of metabolic stress that ramps up when you start too hard. That’s why starting fast increases lactate and worsens performance later.