Causes of Muscle Soreness

Why do some types of exercise seem to cause more muscle soreness than others?

Hard exercise tears your muscle fibers to shreds. If a researcher cuts out a piece of your muscle on the day after you exercise vigorously and looks at it under a microscope, he will see bleeding and disruption of filaments that hold the fibers together as they slide over each other during a contraction.

Muscles contain chemicals called enzymes that help you to convert foodstuffs to energy. When muscles are damaged by hard exercise, they release enzymes, such as CPK, into the bloodstream. Doctors can then measure levels of CPK enzymes in the bloodstream to determine how badly muscles are damaged. Those exercisers with the highest post-exercise blood levels of CPK also have the most muscle soreness. Running fast downhill and lifting very heavy weights cause more post-exercise soreness than other exercises because they cause the most muscle damage; they also take the longest time for recovery.

You can prevent muscle soreness by stopping exercising when your muscles start to feel sore, but then you will not improve. All athletic training is done by stressing your muscles with a hard workout, taking easy workouts until the soreness disappears, and then taking another hard workout.

Checked 9/29/08

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