Why it hurts in fibromyalgia, part 3: After-pain and widespread pain

You can find the video after the text

In this video, I will talk about the most likely explanations for the phenomena of after-pain and widespread pain in fibromyalgia.

My name is Andreas Persson and I am a physiotherapist and specialist in pain and pain rehabilitation. 

I will describe so that anyone can understand, what the most likely explanations are for the pain people with fibromyalgia experience.

In the description, you can find a link to what I say in a text with references to the scientific articles it is based on. 

If you have not seen parts 1 and 2, watch them first, large parts of what I will talk about are based on them. Links to the videos can be found in the description.

In the first part, I talked about the five different pain phenomena in fibromyalgia and we took a closer look at the most likely causes of the first of them, lowered pain threshold.

In the second part, we took a closer look at amplified pain and unprovoked pain. I also talked about central sensitization, the descending pain-modulating pathways, and inflammatory cytokines.

This video will be about the phenomena of after-pain and widespread pain in fibromyalgia. 


For those who have fibromyalgia, it is common to get more pain after loading the body. It can come after household chores such as vacuuming, washing windows, or physical exercises such as strength training or jogging. It is also common to get significantly more pain after a physical examination by a doctor or physiotherapist, as well as after sensory treatments such as a massage or acupuncture.

After-pain is also common in people who do not have fibromyalgia. Usually, the pain comes after a physical overload of a muscle or joint. If the activity did not hurt when it was performed, then the load was at a level that was below the pain threshold, but since it resulted in after-pain, it was still past the level required to lead to a small or several small injuries. In these cases, the after-pain is caused by the inflammatory process that starts locally in the body as a result of injury.

The inflammatory process makes the receptors in the peripheral pain nerves so sensitive that signals are sent when the damaged tissue is used or even when it is not loaded at all. A common example of after pain is delayed onset muscle soreness or DOMS that can happen after exercise. DOMS is caused by small micro-injuries in the muscles and the subsequent inflammation that makes the peripheral pain nerves more sensitive.(1) Usually, the inflammation during DOMS is so mild that the affected does not have unprovoked pain. It usually requires strain or touch of the muscle for it to hurt.

Of course, those with fibromyalgia may experience after-pain for the same reason as those who do not have fibromyalgia, that is, injury and inflammation in the body. But people with fibromyalgia get after-pain easier. 

After-pain can be divided into the phenomena lowered pain threshold and unprovoked pain. Reduced pain threshold due to after pain means becoming more sensitive to loading and stimulation after an activity. An example could be after lifting and carrying a lot of boxes. In the case of a lowered pain threshold, the next day you may have pain from bending forward, which normally does not hurt.

Unprovoked pain due to after-pain can mean that the same person who lifted and moved the boxes has back pain even when he is lying down and does not load his back in any way.

We have talked about lowered pain threshold and unprovoked pain in the two previous videos. What separates the lowered pain threshold and unprovoked pain that comes after and is caused by an activity or treatment is that they are caused by a physiological process that takes a relatively long time. It is common for after-pain to start several hours after the activity. Sometimes it does not start until the day after.

The same time-consuming physiological process that is responsible for after-pain in normal pain-free people, namely local inflammation in the body as a result of small injuries, could be responsible for after-pain in fibromyalgia. 

The reason why those with fibromyalgia easier get after-pain can be that the spinal pain nerves are more sensitive to the incoming signaling from the peripheral pain nerves. This means that weak signals that would not normally be passed on to the spinal pain nerves reach the brain.(2)  

Another possible cause of after-pain in fibromyalgia is inflammation in the central nervous system. As I mentioned earlier, those with fibromyalgia have higher levels of inflammatory cytokines in the spinal fluid.(3-5) Increased production of inflammatory cytokines could start as a result of incoming signals from the peripheral pain nerves or even from the sensory nerves of someone with fibromyalgia when an activity is being performed. 

The production, release, and effect of inflammatory cytokines on nerve cells involved in creating the experience of pain are just like the inflammatory process in the body a time-consuming process, which means that it could explain after-pain in fibromyalgia.

In summary, the most likely reasons why people with fibromyalgia experience after-pain easier than others are that the spinal pain nerves are more sensitive to weak signals from the peripheral pain nerves that start due to minor injuries and inflammation and/or that an activity increases the levels of inflammatory cytokines in the spinal cord which makes the spinal pain nerves to more easily send signals to the brain.

Before we move on to the next pain phenomenon, I just want to explain why I am making this video.

Although I have worked clinically with people who have chronic pain for over ten years and have trained as a specialist in pain and pain rehabilitation, there is much that I do not know about the causes of chronic pain and fibromyalgia and the other symptoms associated with the pain. I also do not know everything about how to treat and manage the pain.

Making this video and hopefully more videos allows me to dive deeper into the research and learn more, and hopefully you will also learn things that you find interesting.

However, the ambition is not only that the videos shall be interesting, but also useful for those who have chronic pain, for those who are relatives, and for those who work with people who are in pain. I hope you want to be part of a journey where we learn more about the causes of, and how to best treat and manage chronic pain.

If you want to be a part of this journey, click the like button. Subscribe to the channel and share the videos you like on social media. It improves the chances for me to continue making similar videos, and for you and others to see them. 

I do not see the videos as one-way communication. I would like to have a conversation on the subjects with you. 

Write in the comments what you think and feel about what I am talking about, if there is something in the video that you think can be improved, if there is something you think is good, and if there is something else that you want me to make a video about.

Now we move on to the phenomenon of widespread pain.

Widespread pain

Having pain in large parts of the body defines fibromyalgia and is included in both the old and new diagnostic criteria.(6,7) Just as with after-pain, widespread pain can be divided into a lowered pain threshold, -that it hurts more easily in different parts of the body when loading or exposing it to sensory stimulation and unprovoked pain – that it hurts spontaneously. 

The unique thing about this pain phenomenon is that it occurs in large parts of the body. What, then, are the most likely causes of widespread pain in fibromyalgia? It is not very likely that local injuries occur more easily in those with fibromyalgia in so many places in the body that it could explain the extent of the pain.(8,9) But if the widespread pain in fibromyalgia is not due to local injuries in the body, then what is the cause?

Because the pain is occurring in such large parts of the body and the cause does not seem to be in the body, it likely originates in the spinal cord.

Just like with several of the other pain phenomena, altered activity in the descending pain modulating pathways is one of the probable causes of widespread pain in fibromyalgia..(9-11) When testing parts of the pain-modulating pathways by exposing any part of the body to pain, the effect on the pain-modulating pathways is not local to the places that are exposed, but general to the whole body.(12)

Testing of the descending pain-modulating pathways by pain stimulation of one part of the body gives a higher pain threshold in the whole body in those who are normally pain-free but a lower pain threshold in the whole body in those with fibromyalgia.(10,11)

This makes it clear that at least parts of the descending pain modulating pathways modulate incoming pain signals from the whole body throughout the spinal cord. This means that the descending pain modulating pathways may be, at least in part, responsible for widespread pain in fibromyalgia.

Another possible cause may be elevated levels of inflammatory cytokines in the spinal cord, just as I have mentioned with several other pain phenomena. As stated earlier, people with fibromyalgia have higher levels of inflammatory cytokines in the spinal fluid, which suggests that there are also higher levels in the spinal cord.(3-5) 

If you assume that the elevated levels of the cytokines are generally found throughout the spinal cord, it is not so strange if that creates pain in large parts of the body. Animal experiments show that adding inflammatory cytokines to the spinal cord can start pain in different parts of the body.(13)  

Another clue is that lack of sleep leads to both elevated levels of inflammatory cytokines and lowered pain threshold throughout the body in normally pain-free people.(5, 14-16) 

A third clue is that when normally pain-free people become ill in for example Influenza, they often experience pain and tenderness in large parts of the body – that is, widespread pain. Influenza causes elevated levels of inflammatory cytokines in the body and the central nervous system.

This means that there is evidence indicating that altered function in descending pain-modulating pathways and elevated levels of inflammatory cytokines can cause widespread pain in fibromyalgia.


So to summarize why it hurts in fibromyalgia. In the videos, I have told you that pain in fibromyalgia consists of five different pain phenomena. Lowered pain threshold, amplified pain, unprovoked pain, after-pain, and widespread pain. 

I also told you about the most likely causes of the various pain phenomena. Common to all the phenomena is that they can be caused by elevated levels of inflammatory cytokines.

Altered descending pain modulation is also a likely cause of four of the five phenomena. Due to its immediate effect, downward pain modulation is probably not the cause of after-pain. 

In amplified pain and possibly also in after-pain the physiological effect of central sensitization where the spinal pain nerves get sensitive faster may also be a cause of the pain those with fibromyalgia experience.  

If you liked this video, press the like button and share it on social media. If you want to see more similar videos, subscribe to the channel. Write in the comments what you think and feel about what I have been talking about, if there is something that you think can be improved, if there is something you think is good, or if there is something else that you want me to make a video about


1. Hotfiel T, Freiwald J, Hoppe MW, Lutter C, Forst R, Grim C, et al. Advances in Delayed-Onset Muscle Soreness (DOMS): Part I: Pathogenesis and Diagnostics. Sportverletz Sportschaden. 2018;32(4):243-50.

2. Brodal P. A neurobiologist’s attempt to understand persistent pain. Scand J Pain. 2017;15:140-47.

3. Bjurstrom MF, Giron SE, Griffis CA. Cerebrospinal Fluid Cytokines and Neurotrophic Factors in Human Chronic Pain Populations: A Comprehensive Review. Pain Pract. 2016;16(2):183-203. 

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7. Wolfe F, Clauw DJ, Fitzcharles MA, Goldenberg DL, Häuser W, Katz RL. 2016 Revisions to the 2010/2011 fibromyalgia diagnostic criteria. Semin Arthritis Rheum. 2016;46(3):319-29.

8. Hawkins R. Fibromyalgia: A Clinical Update. J Am Osteopath Assoc. 2013;113(9):680-9. 

9. Harte SE, Harris RE, Clauw DJ. The neurobiology of central sensitization. J Appl Biobehav Res. 2018;23(2):e12137. 

10. Potvin S, Marchand S. Pain facilitation and pain inhibition during conditioned pain modulation in fibromyalgia and in healthy controls. Pain. 2016;157(8):1704-10. 

11. Harper DE, Ichesco E, Schrepf A, Hampson JP, Clauw DJ, Schmidt-Wilcke T, et al. Resting Functional Connectivity of the Periaqueductal Gray Is Associated With Normal Inhibition and Pathological Facilitation in Conditioned Pain Modulation. J Pain. 2018;19(6):635.e1-e15. 

12. Nir RR, Yarnitsky D. Conditioned pain modulation. Curr Opin Support Palliat Care. 2015;9(2):131-7. 

13. Ji RR, Nackley A, Huh Y, Terrando N, Maixner W. Neuroinflammation and Central Sensitization in Chronic and Widespread Pain. Anesthesiology. 2018;129(2):343-66. 

14. Schuh-Hofer S, Wodarski R, Pfau DB, Caspani O, Magerl W, Kennedy JD, Treede RD. One night of total sleep deprivation promotes a state of generalized hyperalgesia: a surrogate pain model to study the relationship of insomnia and pain. Pain. 2013;154(9):1613-21.

15. Staffe AT, Bech MW, Clemmensen SLK, Nielsen HT, Larsen DB, Petersen KK. Total sleep deprivation increases pain sensitivity, impairs conditioned pain modulation and facilitates temporal summation of pain in healthy participants. PLoS One. 2019;14(12):e0225849.

16. Mullington JM, Simpson NS, Meier-Ewert HK, Haack M. Sleep loss and inflammation. Best Pract Res Clin Endochrinol Metab. 2010;24(5):775-84. 

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