You know the feeling. You wake up the day after you’ve started a new workout routine and you are stiff and sore all over. What happened?
Damage, that’s what. And you can thank your immune system for the pain…
Muscle soreness myths
But first let’s just talk about what is NOT causing the pain: Lactic acid. I’ll talk more about Lactic acid in a future post, but right now I want you to know one thing: the burning you feel in your muscles when you exercises IS caused by lactic acid (scientifically – it’s a build up of hydrogen ions which slightly lowers the pH of you muscle’s chemistry). But then you stop and the burning goes away. About 45 seconds later, the lactic acid is almost all gone from the muscle. So let’s be clear, the Lactic Acid DOES NOT cause the pain you experience the next day.
What really causes muscle soreness
Remember when we talked about how eccentric contractions cause damage to the muscle and then the muscle adapts by creating more sarcomeres? If you don’t please go back and read “Your muscles are out of breath but you’re getting stronger”. Once this damage has been done, your immune system kicks in. (as it does with any infection or other kind of tissue damage). Immune cells and chemicals flood the area where the damage has occurred, with all a manner of biological repair machinery – and in the process it destroys some healthy tissue. Your immune system isn’t perfect.
The pain, which usually takes 24 hours to really get started, is from the immune reaction to its own imperfect healing process. The extent of the damage caused by the exercise will dictate the degree and length of pain you experience. Some people might have a day of general soreness to the exercised area and about 48 hours later they’re ready to damage the muscle again. Take note, if you overdo your workouts you might have a week of really uncomfortable, achy soreness.
After damage, muscle growth begins
The interesting thing about this damage/repair cycle is that only one exposure is enough to create a noticeable adaptation. Let me explain: imagine you decide to do three rounds of those eccentric push-ups I explained in a previous post. Say you were able to do 5 really good slow ones in each round. Then 24 hours later you’d probably feel some pretty good soreness in your chest, triceps, and your abdomen. Now, if you repeated the exact same process one week later you would not have the same level of soreness as you did the first time you did the exercise. You will probably still be sore but not to the extent you were the first time. If you want to feel that same level of soreness gain, you’d have to add in another push up or two per round. Or do a 4th round. You get the picture right? After you’ve adapted, you have to make the stress slightly harder to create the same amount of damage.
I don’t advise that you try and go harder every time you exercise. I just want to explain what is happening to your muscles, over time, in an understandable way.
So let’s sum up:
- Lactic acid causes a burning sensation at the time of the exercise.
- Muscle damage occurs.
- Then your immune response causes the delayed muscle soreness the next day.
Heal, and repeat.
Read all of Matthew’s articles on health and fitness here.