When people first work out after a long time, there’s nothing like experiencing the harsh soreness that follows in the next couple days. However, as people continue to exercise, that soreness slowly diminishes. Why does this happen? While certainly convenient, why is it that one day people can be incredibly sore from an exercise, and a week later that same exercise barely bothers them?

This soreness in the exercise science world is known as DOMs, or delayed onset muscle soreness. Essentially, this soreness happens anywhere between six to eight hours after a person works out, and may last up to 48 hours depending on the severity of the workout and when a person worked out last. However, this type of soreness is different for everyone and often varies from person to person. Usually, DOMs are witnessed the most when people experience a new type of workout or training, or they have not worked out in a long time or ever.

“Soreness is caused because the body is trying to make adjustments within the muscles to better prepare itself for next time.”
Addressing myths
This soreness is caused because the body is trying to make adjustments within the muscles to better prepare itself for next time. So if people train for the same length of time and do the same activities every day, the muscles will become more prepared for these exact activities and slowly will not be as sore. However, this does not mean people are not building muscle.

It turns out that certain exercises might build muscle more quickly than others. For instance, when people run downhill, lower into a squat or push-up position, or lower weights, they are experiencing eccentric contraction, and this can lead to the muscles lengthening as they contract. While this can cause sore muscles, it might also cause people to not see muscle growth after their initial workouts.

One myth people commonly tend to believe is the phrase no pain, no gain. It turns out, this could not be farther from the truth. A good workout should not be measured by how sore a person is the next day. Just because a person is not sore the next day, or can actually get out of bed, it does not mean that he had an ineffective workout. Instead, a person can still have a great workout but not feel the effects and his muscles still might have grown.

Sometimes, people push the envelope because they do not feel sore and feel as though they did not work hard enough. For instance, if 24 hours goes by and they are not sore anymore, a person might head back to the gym or continue to work out. However, if they begin the same tough regimen they began before and their body is not ready yet, they may end up experiencing muscle failure and might have a hard time completing any type of workout.

“If, after three days, you try to do the same exercise and you cannot because you go immediately to muscle failure, you’ve done too much,” National Academy of Sports Medicine (NASM) certified personal trainer Monica Vasquez told the Daily Bur

Changing exercises can help continually make muscles sore.
Understanding the metabolic process
People also tend to believe that they are sore because of excessive lactic acid build up in their muscles. It turns out this is simply not true. A study published in Clinics in Sports Medicine found that the soreness is caused by minute muscle damage and tearing, as well as damage of the surrounding tissues. Luckily, this injury is so minor that people can quickly recover thanks to the body’s attempt at healing the muscles by adding protein to them. So, when people break those fibers apart, protein is involved and lactic acid has nothing to do with it.

Instead, lactic acid is involved in the metabolic process, which occurs all the time, not just when people work out. As people work out, the breakdown of molecules for energy happens to the muscle area, which is why people might feel their muscles burning toward the end of a tough exercise. However, lactic acid does not get involved until after the work out to help inhibit the molecules in the muscles from breaking down too quickly. Within an hour, that lactic acid is gone.

So there you have it. Working out can sometimes lead to sore muscles, and other times it does not, but that has little effect on the overall muscle growth. Just because people’s muscles are sore does not mean they are filled with lactic acid, and workouts can become easier over time if you continually do the same activities without change. However, sometimes changing up the training regimen or trying new activities that test the muscles in different ways can cause the muscles to continually break and rebuild, which can lead to greater fat burn and a more toned body.