Even today many people believe that the muscle pain that is felt in the days following physical activity is caused by an accumulation of lactic acid, however this is not the case and that of lactic acid is just a false myth that is still quite widespread!

It is actually DOMS, an acronym from English Delayed Onset Muscle Soreness, or Delayed Onset Muscle Soreness. This disorder is very common among those starting to practice a new sport but also among sportsmen who perform a new type of training and can occur after any kind of physical effort.

Why is it not lactic acid?

From a physiological point of view we know that lactic acid is produced by the muscle during an intense and rapid effort, for example in the acceleration of a physical exercise. The lactic acid produced can be used by the muscle fibers themselves or pass into the blood that transports it to the liver where it is metabolized with a certain rapidity; in fact, after a couple of hours from the end of the exercise, its concentrations in the blood return to normal.

So why do we feel pain?

Although the exact pathophysiological path of DOMS is not yet known, we know that these pains are independent of lactic acid and the main mechanism believed to be responsible for the onset of symptoms is structural damage to muscle cells.

This damage can be due to unfamiliar sporting activities or following eccentric or isometric exercise: an example of eccentric exercise is running downhill while an exercise is defined as isometric when the muscle contracts without stretching or shortening as if to push hard. arms against a wall. 

Structural damage to muscle fibers in turn leads to further protein degradation, apoptosis and local inflammatory response, which together are responsible for the perceived pain. In practice, following an intense effort to which our muscles are not used to, micro-injuries are formed in the muscles that cause pain.

The development of clinical symptoms is typically delayed and in fact the pain appears about 24-48 hours after exercise, as a result of local and systemic physiological responses, and then resolves within a few days in relation to the duration and intensity of the effort. performed.

So, we said that lactic acid is eliminated after 2 hours from the end of the exercise and that, instead, muscle pains arise at least 24 hours after training: this is further confirmation that the pain cannot be due to an accumulation of lactic acid.

Summing up:

DOMS are micro lacerations of muscle tissue due to the excess stress to which the muscle is subjected during physical activity; these lacerations trigger an inflammatory response which results in the sensation of pain and occur more frequently when you are out of training or when you practice unusual or particularly intense workouts BUT ...

... After the muscular effort it is these small micro-traumas that allow the body to adapt to exercise by improving its functional capabilities! The damaged cells heal and the damaged tissue is thus rebuilt, furthermore there is a process of functional reorganization and adaptation that leads to an increase in muscle resistance and consequently an improvement in muscle performance.

To conclude, here are some suggestions to limit the onset of DOMS after physical activity:

  • Before starting the actual training, do a nice warm-up so as to prepare the muscles for training and promote greater muscle elasticity.
  • Have a well-structured workout by a professional and set up gradually in relation to your skills and your level of training.
  • Finish your workout with a good cool-down session to prepare the muscle for rest and aid in the recovery process.
  • Allow your body and muscles to recover adequately by letting enough time pass between one workout and the next.


  • Hotfiel T, Freiwald J, Hoppe MW, et al. Advances in Delayed-Onset Muscle Soreness (DOMS): Part I: Pathogenesis and Diagnostics. Sportverletz Sportschaden. 2018; Available at

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