Most of us have done hard work or exercise and the next day felt sore, more sore even than during the activity. This is known as Delayed Onset Muscle Soreness - DOMS. What is going on in our muscles to make us feel pain?

Scientist don’t agree on what exactly is going on, but most agree that it’s in part due to the fact that muscle fibers are being torn. During exercise cell membranes are ruptured. This is the reason rest is so crucial when trying to build muscle. You need hard workouts, but you also need rest to recover and let your muscles repair themselves. The percentage of tissue torn is small, this site says less than 5 percent is affected.

Studies also show that eccentric (lowering) movements contribute more to DOMS than the concentric movement, or the lifting phase. An easy way to remember these two terms is to think “Eccentric” is “Extending,” such as during the extention of a bicep curl. When you push off the floor in a push up you are performing the concentric phase of the movement, when you lower yourself you are performing the eccentric part of the exercise. Both parts are important but eccentric movements only can be helpful if the exercise is too difficult to perform the concentric movement. Doing only the eccentric part of an exercise is also called a “negative”. For example, if you want to be able to do a pull up on a door frame but aren’t strong enough yet, get a chair and hoist yourself up to the “up” position of the pull up. Then curl your legs up behind you, putting your full weight on your arms and slowly perform the eccentric part of the exercise. If you work at this exercise consistently (allowing yourself sufficient time to recover between sessions), you’ll be able to do a full pull up before long even though you were not performing the concentric part of the exercise. Here’s a page with more on how to do a pull up, including a section on negative pull ups.

Why can you do a negative pull up but not a regular pull up with both the concentric and eccentric phases? Muscle fiber can handle 40% more weight during the eccentric phase than during the concentric and if used correctly can lead to a lot of muscle growth. That means if you weigh 200 pounds and can do a full pull up, you can do a full negative with an extra 80 pounds.

Posted by Bonnie under exercise, health