Why do our muscles get sore?

By Casey Frye, CCNN Writer

It’s completely natural to feel sore up to 2 days after a good workout.

After giving our muscles a hard workout, it’s not unusual to feel alive and invigorated with energy immediately afterwards. However, the next day is a completely different story, as the slightest movement causes mega soreness. So, why exactly do our muscles get sore?

Well, health experts call that post-workout pain “delayed onset muscle soreness” (DOMS), and it has to do with how our muscles work. Our muscles generate force in different ways, like “concentric” and “eccentric” contractions.

Concentric contractions happen when the muscle produces force as it shortens, like when you’re lifting up a weight for a bicep curl. During concentric contractions, the muscle is able to generate more force than whatever load it is carrying.

On the other hand, eccentric contractions are when the muscle generates force while getting longer. An example of this is when your biceps uncurl or when you go down into a squat. Eccentric contractions cannot produce more force than the load being carried. As a result, the muscle experiences microscopic tears, all the way down to the tissue that connects the meat to the bone. The areas get inflamed (swollen) and soon thereafter you’ll experience DOMS!

Muscle soreness usually starts about 12 hours after the physical activity and can last anywhere from 1 to 3 days. While this process of ripping your muscles apart sounds dangerous, it’s actually part of the natural workout process! In fact, the muscles get bigger and stronger as they repair the tiny tears, so during the next workout, they’ll be more powerful.

Keep in mind that experiencing DOMS doesn’t necessarily mean you’ve completed a proper workout. In fact, if the pain lasts for more than 3 days, it may be a sign of muscle damage. If your muscles are swollen and painfully tender, the American College of Sports Medicine recommends that you should see a doctor straight away. With that said, workouts are tough. If you go through a grueling workout that leaves you almost unable to walk the next day, just know that your muscles are growing stronger with every sore step.

Featured image courtesy of Matthew Kenwrick on Flickr. Image of weights courtesy of clumsy_jim on Flickr.