Many people who start a new form of exercise for the first time are surprised to discover that the pain they experience in their muscles is actually more intense 2-5 days after doing the workout. So today I thought we would have a look at the science behind delayed onset muscle soreness (DOMS).
The process in which we stress the muscles leads to a chain of events that involve both the structural damage and an inflammatory response.
Structural Damage - When we exercise our muscles by pushing them past what is easy and comfortable, we are actually causing slight tears, or damage, to the muscle fibres. The sarcolemma, also referred to as the muscle membrane, is stressed and this can be seen by increased concentrations of specific enzymes in the blood. The more intense the training, the more damage that occurs. This means that your body experiences varying degrees of muscle fibre breakdown.
Because of this cellular breakdown, and assuming the body has enough materials to work with, muscle hypertrophy begins to occur. This is just a fancy way of saying that the muscles begin to repair and rebuild bigger, stronger and more resilient than before. During the initial stages of this process there is an increased number of white blood cells that come to asses the damage and it is this tearing and damage, as well as the slight cellular inflammation which occurs that causes the initial pain and discomfort.
Inflammatory Response - This increase in white blood cells is the body’s way of reacting to any damage on a cellular level. The damage to the muscle fibres activates mononucleated cells, which then signal to other inflammatory cells to come join the party. Neutrophils, which are a type of white blood cells, invade the injured muscle and whilst they are there they release immunoregulatory substances (kind of like party invites) that are called cytokines, which in turn attract even more inflammatory cells.
Unfortunately this then creates even more discomfort. As if that wasn’t enough, just when it seems the party is dying down, some late comers join in and a second phase of macrophage occurs. This means even more white blood cells come to clean up any leftover debris and assist in the regeneration of your muscles.
This whole process happens over a series of days and is why it is so important to incorporate rest days when training specific muscle groups, as well as ensuring you get enough protein in your diet. Last but not least, get enough sleep because this is when most of your regenerating occurs!