In the first of this 4-part series we’re talking about what exactly delayed onset muscle soreness (DOMs) is and whether it is a good or a bad thing.

Stay tuned for part 2 where we’re sharing what the research says are the foods to eat to minimise the chances of developing DOMs. In part 3, we’ll be looking at herbs and supplements to speed up recovery and reduce the soreness. In part 4 we’ll be looking at what you can do to reduce the possibility of being sore after your workout and what to do when you’ve gone hard and can’t walk the next day.

What are the symptoms of DOM?

Symptoms of delayed onset muscle soreness (DOMs) include soreness in the muscle that has been used, increased fatigue, and reduced function within the affected muscles. You will notice it within 8-24 hours of exercise and the symptoms peak within 48 hours. It typically disappears within 92-hours but can last up to 14-days. How long you are sore for depends on the intensity and duration of the exercise, your training buildup to it, and how susceptible you are to muscle damage. Your nutritional status and general level of inflammation can affect your susceptibility.

running is an example of an eccentric exercise

What causes DOM?

DOMs is most often triggered by eccentric exercise. Eccentric exercise is anything which requires your muscles to contract whilst lengthening. Examples include resistance training, long distance running, downhill running, and intermittent high intensity exercise.

DOMS is caused by tiny tears in your muscle fibres. Your body responds to this microtrauma with an inflammatory response which is why the swelling occurs. Your body is amazing at adapting to new stimuli, so less damage occurs if your body has experienced this sort of exercise before. This is why increasing your exercise intensity or duration by no more than 10% is a great way to prevent DOMs.

The eccentric lengthening that happens during the exercise increases muscle cell membrane permeability. This increased permeability allows calcium held within the muscle cell to move out of the cell and into your cytoplasm. The departure of the calcium damages muscle proteins.

a mitochondrion

Your mitochondria do their best to mop up this influx of calcium but eventually they get overwhelmed and don’t work as well as they did. Your body has a mechanism for dealing with this. It kills off underperforming mitochondria and replaces them with new, fully functioning ones. Sounds extreme? Don’t worry, it’s a normal part of your immune and energy systems that happens every day without you being aware of it.

As a result of this immediate damage, in comes the cavalry. Your immune system responds with a flood of mast cells, neutrophils, lymphocytes, and eosinophils who tidy up the damage. This inflammatory process begins the process of healing and adaption. Muscle cells are repaired leaving them bigger and stronger than before.

The balance between avoiding DOM and building muscle

And herein lies the delicate balance because it is the tiny muscles tears and the inflammatory response to the damage that encourages your muscles to adapt to the new stimuli. This makes them bigger and stronger than before and better able to cope with what is now required of them. Avoiding muscle tears is not the answer. There is a balance between the exercise stress that’s needed to trigger increases in muscle mass and strength; and using strategies that can speed up this recovery period.

The key is to:

  1. manage the extent of the damage through gradual adaption
  2. provide your body with the nutrients needed to tidy up and rebuild
  3. ensure your cells are appropriately hydrated before, during and after exercise; and
  4. consistently use recovery protocols that support your body in this repair process

In the next part of this 4-part series, we will look at the research supporting the foods that can minimise DOMs and support the recovery process.


Harty, P., et al., (2019). Nutritional and Supplementation Strategies to Prevent and Attenuate Exercise-Induced Muscle Damage: a Brief Review. Sports Medicine Open. 5, (1). doi: 10.1186/s40798-018-0176-6

Owens, D.J., et al., (2019). Exercise-induced muscle damage: What is it, what causes it and what are the nutritional solutions? European Journal of Sport Science. 19 (1), 71-85. doi: 10.1080/17461391.2018.1505957.