To answer this question you need to know that the inflammatory response is very much influenced by the (autonomic) nervous system. If you want to know more about the nervous system and in particular when which part of the autonomic nervous system is active click HERE. And that muscle aches/pain/soreness days after a workout are mainly caused by the inflammatory response.
To give you a quick summary: the autonomic nervous system is part of the peripheral nervous system (consisting of all the nerves in your body) and controls the basics for life (think of blood pressure, heart rate and respiration). The autonomic nervous system consists of two parts:
1 The 'stress system' aka the sympathetic nervous system (SNS) for the ‘fight or flight response’
and 2 The 'rest system' aka the parasympathetic nervous system (PNS) for ‘rest and digest response’.
You use the stress system (SNS) during times of action: training, doing a presentation or watching a scary movie.
And you use the rest system (PNS) when you are fully relaxed doing (almost) nothing.
The stress system (SNS) can influence the inflammatory response by releasing (nor)-adrenaline and cortisol, these hormones are known to suppress inflammation.
So it’s easy: stimulate the SNS and suppress inflammation!
But the autonomic nervous system works (just as it says in the name) automatically, so how could we possibly influence that?
There has been done quite a lot of research on the subject and researchers discovered decades ago that the resting system (PNS) is easily stimulated (read about that HERE). But stimulating the SNS remained a mystery, until only a few years ago.
Activating the SNS.
As said you can suppress inflammation by activating the SNS, but how? The SNS is activated in times of stress and doing things that excite you so go: bungee jumping, skydiving or crocodile wrestling.
Luckily there is also an easier way: breathing exercises, yes again: just as with the PNS.
But this time you will have to do the exact opposite: a deep inhale and a short exhale for around 30 breaths. This is called hyperventilation and increases the amount of oxygen in the blood and simultaneously decreases CO2 levels. During this technique you can feel some light-headedness and tingling in the hands and feet. After one set of 30 breaths most people are able to hold breath for 1.5 to 2 minutes.
This breathing technique has two major effects: it stimulates anti-inflammatory agents and raises pH.
Hyperventilation has been proven by research [1,2] to releases anti-inflammatory agents. Known as the Wim Hof method this technique was tested on test subjects in a hospital setting. The test subjects were injected with a dead bacteria that normally caused fever like symptoms. The group was split in two, one group got training by Wim Hof consisting of various hyperventilating breathing exercises and the other group got no training. During the experiment, the not trained group got sick within 30minutes whereas the trained group didn’t got sick at all. The trained group showed increases in: adrenaline and IL-10 (anti-inflammatory) and a decrease is pro-inflammatory TNF, IL-6 and IL-8.
The trained group showed increases in: adrenaline and IL-10 (anti-inflammatory) and a decrease is pro-inflammatory TNF, IL-6 and IL-8.
This technique is also known to raise pH due to the decreased CO2 levels in the blood. By raising the pH the body becomes more base. Wim Hof’s method has showed to be able to increase the pH to 7.75  were the normal average lies between 7.35-7.45. This has numerous consequences, raising pH is associated by de-activating acid-sensing ion channels that normally activate (nociceptive) pain sensors . So by raising pH you can restrict pain sensing signals: you experience less pain.
Combining this breathing technique with ice baths is for that reason often used, because ice baths can be very painful. But as there is a chance of passing out, you should never perform this technique alone and/or underwater. Read more about the effects of ice baths HERE.
So you can decrease pain by decreasing inflammation:
Stimulate the SNS: do 30 breaths focusing on breathing in. Inhale deep and exhale short, this will produce some light-headedness and tingling/numbness in hands and feet. After 30 breaths you exhale and try to hold your breath for as long as you can (should be for more than 1.5 min).
Do not do this underwater.
If you want to learn more: Wim Hof (aka the iceman) wrote several books about this breathing method.
- Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans
- The role of outcome expectancies for a training program consisting of meditation, breathing exercises, and cold exposure on the response to endotoxin administration: a proof-of-principle study
- acid-sensing ion channels in pain and disease