Do you ever have sore muscles the day after exercise?
The kind of soreness that stops you from exercising that day?
Soreness that you could really do without (and doesn’t actually have to be part of your life)?

You probably have delayed-onset muscle soreness (1)…

What is Delayed-Onset Muscle Soreness?

delayed muscle fatigue
Delayed-onset muscle soreness is the sort of muscle pain you get the day after exercising (usually when you wake up the next morning). It typically lasts for 3-5 days.
The bad news is some people are more susceptible than others.

Symptoms of Delayed-Onset Muscle Soreness

  • tender muscles
  • pain and stiffness when moving
  • swelling
  • muscle fatigue
  • short-term loss of muscle strength

Summary

Delayed-onset muscle soreness usually starts the day after exercising.

Who Can Get Delayed-Onset Muscle Soreness?

Anyone from elite athletes to beginners can experience delayed-onset muscle soreness. It’s more common if you’re doing a new exercise routine. But some people are more susceptible than others to muscle soreness and pain after exercise.

Summary

Anyone from beginners to elite athletes can get delayed-onset muscle soreness.

What Causes Post-Exercise Muscle Pain?

Your body makes inflammatory molecules in response to exercise and releases them into your bloodstream. They are called ‘cytokines’.

Cytokines are useful while exercising and immediately afterwards. But not as useful when they stay in your body.

The main cytokine athletes should know about is called interleukin-6 (IL-6). This molecule increases more than any other cytokine while exercising (2).

Summary

Inflammatory molecules called 'cytokines' are released during exercise.

IL-6: The Good and The Bad

IL-6 is good in small doses, which helps stimulate glucose production and repair muscle damage.

With enough rest and recovery, IL-6 levels reduce again and your body adapts to your training program. But problems arise when IL-6 levels stay high.

IL-6 stays high when you overtrain or don’t take enough time between training sessions. This leads to muscle breakdown, which reduces your nutrient absorption (particularly iron and zinc) and can stop you from adapting to the new training routine (3).

IL-6 also stimulates the release of other inflammatory molecules like C-reactive protein (4).
But some people are more susceptible to higher IL-6 levels than others.

Summary

Chronically raised levels of inflammatory cytokines like IL-6 can cause muscle damage.

Are You More Susceptible to Inflammation?

If muscle pain after exercise is usual for you, it could be down to your genes. Actually, there are many genes associated with sport performance and recovery.

People with certain genes are at greater risk of muscle damage and may require longer recovery after exercise (5). 

The most significant genes determining your response to exercise are:

  • IL6 (rs1800795) - variations in this gene can increase IL-6 levels.
  • ACTN3 (rs1815739) - this gene changes the composition of your muscle fibres.
  • TNF (rs1800629) - this gene encodes for another inflammatory molecule called TNF-alpha.
  • IGF2 (rs680) - encoding insulin-like growth factor 2.


The good news is you can tailor your training and diet if you know which genes you have so you can maximise recovery and adaptation - and minimise your risk of injury too.

Summary

Some people have genes which predispose them to delayed-onset muscle soreness more than others.

Delayed-Onset Muscle Soreness: Wrap-up

We each respond differently to exercise and understanding your response to your training based on your genes can be very beneficial in working out what works for you.

If you have a genetic tendency to higher IL-6 levels you may have an increased risk of muscle pain, injury and prolonged recovery.

By knowing your genes you can know exactly what to do to reduce muscle pain and improve your training.

And make sure you’re doing these things to reduce delayed-onset muscle soreness.