Hey! I totally feel that “pump” and that sour burn when the pace gets high. Lactic acid is just the by‑product of glycolysis when your muscles need energy faster than your blood can clear it, so it builds up and makes the muscle feel all tight. ATP depletion is the opposite problem – when you’re pulling the same effort too long, the stored ATP runs out and the muscles can’t contract as smoothly. That’s why you feel heavier, slower, and can’t maintain the same speed. How I handle it? First, I break the workout into chunks: push hard for a set, then recover a little to let the acid wash out. I’ll do a 5‑minute sprint, then 2‑minute walk, repeat. That keeps the lactate from stacking up. Second, I’m big on fueling – carbs before a long run, and a quick carb snack right after a hard session so the ATP pool can refill faster. Third, I do active recovery: low‑intensity jogs, dynamic stretching, or even a slow bike ride. That keeps blood flowing and helps clear lactate. If you want to tweak your plan, let’s keep those intervals in mind. Maybe we can add a tempo run where you stay just below that lactate threshold, or switch to a longer steady‑state session to build endurance and improve how quickly your body clears acid. Also, a short strength block can help your muscles use ATP more efficiently. Let’s swap numbers and see what’s working, and then we’ll punch that next training block with a little more science and a whole lot of motivation!