Monday, September 22, 2008

Why Exercise Causes Muscle Soreness

My sedentary, overweight buddy just emailed me and said he was going to the gym for the first time in 18 months. I quickly emailed him back and told him to take it easy in the workout, because he was certain to be sore in the next couple of days.

As anyone who has started an exercise program knows, doing a new activity leads to muscle soreness in the days that follow. But why is that? And why does it take so long for this to happen?

Researchers asked the same questions, and published their findings in the Journal of Orthopedic Sports Physical Therapy. Sixteen sedentary young men did an advanced resistance training workout, doing three sets of seven exercises at 80% of their one repetition maximum.

Reference: J Orthop Sports Phys Ther. 1991;13(6):316-21.Related Articles, Links The Effect of One Session of Muscle Soreness-Inducing Weight Lifting Exercise on WBC Count, Serum Creatine Kinase, and Plasma Volume. Franklin ME, Currier D, Franklin RC.

This is not the type of workout I'd give a beginner, because it would lead to extreme muscle soreness. But that was the point of the study, and I'm sure the subjects knew what they were getting into.

This workout significantly increased White Blood Cell counts (a marker of inflammation), as well as an enzyme called Creatine Kinase (which is a marker of muscle damage). Subjects also experienced Delayed Onset Muscle Soreness, that's the tenderness and soreness we all experience in the days following a new workout. Surprisingly, soreness often peaks 24-48 hours after the workout (in fact, I'm writing this on a Monday night and the soreness from my Sunday morning leg workout has just reached its highest level).

Researchers believe the inflammation from a new workout causes swelling around the muscle fibers, and therefore leads to soreness and tenderness.

The best treatment is prevention. Just don't do too much when you are getting back into workouts! Start each new program by doing only one set of each exercise for the first two sessions. Choose a weight that you can do 15 times, but do only 10-12 repetitions. Don't go to failure - the point where you can't complete a repetition with good form - in any exercise in your first workout on a new routine.

Train safe,

Craig Ballantyne, CSCS, MS

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