Burning During Exercise Differs from Muscle Pain After Exercise

The burning you feel in muscles during intense exercise is different from the burning and pain you feel after exercising. Burning during intense exercise is caused by the acidity from accumulation of lactic acid. When your muscles cannot get all the oxygen they need to convert food to energy during intense exercise, lactic acid accumulates in muscles, makes them more acidic, and the acidity causes a burning feeling. Excess lactic acid is cleared from the muscles within seconds after stopping exercise.

Lactic acid is good because it is the most efficient fuel for muscles during exercise. It requires less oxygen for energy than virtually all other fuels. Sodium bicarbonate (baking soda) neutralize lactic acid in muscles during intense exercise and helps athletes to exercise longer (Medicine & Science in Sports & Exercise, October 2006). Caffeine (the amount in four cups of coffee) reduces muscle burning during intense exercise (International Journal of Sport Nutrition and Exercise Metabolism, April 2009). More on lactic acid

Burning or pain eight to 24 hours after exercising is usually caused by damage to the muscles themselves. The longer you stay in the burn during exercise and the greater the force on your muscles during exercise, the greater the muscle damage. Most athletes train by taking a hard workout on one day, damaging their muscles and feeling sore on the next, and then going at low intensity for as many days as it takes for the soreness to disappear. When muscles heal from hard force on them, they become stronger. Athletes recover from hard exercise actively by exercising at low intensity. They rarely take days off. Exercising at low intensity during recovery makes muscles more fibrous which protects them from injury when they are stressed again.