When you work out really hard and your muscles burn, the buildup of lactic acid might help your muscles refill energy faster—but after lifting weights, less lactic acid means slower recovery.

During high-intensity exercise on a low-carbohydrate diet, lower blood lactate levels occur because muscles have less glycogen to break down for energy, and this does not mean the body is using energy more efficiently—it reduces the ability to maintain high-intensity effort.

After a short, super-hard workout, your muscles refill their energy stores way faster than after a long, slow one—even if you eat the same amount of carbs.

Lifting weights refills muscle energy slower than sprinting or HIIT, maybe because you don’t build up as much lactic acid and your muscles get more sore from stretching under load.

When trained men do certain types of weightlifting workouts, their bodies produce more lactic acid compared to other workout styles, which means their muscles are working harder and under more stress.

Trained athletes on low-carbohydrate or ketogenic diets have lower blood lactate levels during high-intensity exercise compared to those on higher-carbohydrate diets, due to reduced breakdown of muscle glycogen.