Why Do We Get Sore After Working Out?


Soreness and Working Out

For some it is a sign of hard work and progress. For others it is the reason exercising proves so difficult. Regardless, we’ve all felt it at some point or another. DOMS (Delayed Onset Muscle Soreness) is the official name for that terrible feeling in your muscles the morning after a workout.

Soreness: The Myths

Perhaps the most common myth when it comes to soreness has to do with what actually causes it. Ask people what they believe causes muscles to feel sore after a workout and you’re likely to hear the words “lactic acid” pop up more than a few times. That is because it is often believed that it is the buildup of lactic acid in the muscles that causes the muscles to feel sore. This, however, is not true. While Lactic Acid is indeed the primary cause of muscle “burn” during periods of high activity, it plays almost no part in the delayed soreness. (1)

Soreness: The Truth

So what exactly causes DOMS?

Well, we don’t know exactly.

Muscle soreness tends to be more common when a person’s body isn’t used to performing a particular type of exercise. For example, an experienced runner might feel nothing after running a few miles and yet be extremely sore after some light weightlifting.

It is most commonly believed that micro tears in the muscle tissue lead to soreness. The body heals the torn muscles by sending fluids to the area. These fluids cause inflammation in the affected area which further amplifies the pain. (2)

What Does Soreness Mean?

So if you’re reading this perhaps you’re wondering whether soreness is in any way an indication of progress. Does all that pain mean that your workouts are paying off?

Sort of.

Soreness indicates that a muscle has been damaged. Some muscle damage is good because it is the healing of damaged muscles that causes these same muscles to become bigger, so if soreness is an indication of muscle damage then soreness is also an indication that your muscles are becoming bigger and stronger. (2)

However, just because a muscle doesn’t feel sore doesn’t mean an exercise was ineffective. Muscles seem to adapt to exercises that are constantly repeated. If you don’t feel soreness after a heavy workout session it doesn’t mean your muscles aren’t becoming stronger. Soreness is also not an indication of how fit you are. Someone who exercises regularly might feel sorer than someone who doesn’t and vice versa. There are many factors that play a role in the amount of soreness a person experiences such as the actual muscles being used, the exercises being performed, and even genetics. (2)


How long you rest during a period of DOMS depends on how sore you feel. Since your muscles grow and become stronger by healing, it is optimal to allow them to rest at least a day before continuing exercise. (3)

For more intense levels of soreness a few more days may be required. This is especially true for those that are just starting to exercise. High levels of soreness can lead to lower levels of muscular strength. (4) This can make you perform at suboptimal levels and thus, by attempting to exercise with muscles that are still recovering, you risk hindering your progress. It may be difficult to believe, but sometimes resting is the best thing to do if you want to see faster results.

Instances of severe soreness can also be an indication of overworked muscles. If the soreness prevents you from moving a part of your body, this could mean that you worked those muscles too hard. Since muscles tear during heavy exercise, too much work can lead to levels of muscle damage that go beyond what is healthy.


Whether you’re in the group that enjoys feeling sore or the group that absolutely hates the feeling, there is good news. If you like feeling sore, that’s great! Soreness is inevitable and is an indicator that your workout had at least some effect on your muscles. If you hate the feeling, don’t worry, your body will eventually adapt to exercise and you’ll quickly stop feeling the dreaded burn make its way up your legs with every step. Regardless, treat soreness as proof of your decision to live a healthier lifestyle. After all, we all know how the saying goes: “No Pain. No Gain.”

(1) http://www.ncbi.nlm.nih.gov/pubmed/15308499
(2) https://web.archive.org/web/20140822055841/http://www.afafa.nl/Info/page10/page43/files/is-postexercise-muscle-soreness-a-valid-indicator-of-muscula…-_-strength-0026-conditioning-journal.pdf
(3) http://www.ncbi.nlm.nih.gov/pubmed/12618576
(4) http://journals.lww.com/nsca-scj/Citation/2001/08000/Recommendations_for_the_Avoidance_of_Delayed_Onset.1.aspx

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