The weather has changed in Whatcom County. The winds are blowing a cold chill and the autumn season has arrived. The change in seasons brings bright leaves, blueberries in the mountains, snowcapped peaks in the distance, and harvest festivities around town. The seasonal change also brings darker days, cooler temperatures, and increased precipitation.
For many people, a weather change can mean an ache or pain becomes more pronounced. You or a friend may have commented that a knee hurts more when it is cold or it rains.
This may sound like an old wives’ tale, but there is a physiological process that explains this phenomenon. It is not in your head! The weather can and does affect a pain experience based on changing ion channels.
All pain experiences are complex and incorporate multiple body systems interactions. This article is going to briefly cover one small aspect of the large puzzle we call pain.
A Brief Overview of the Nervous System
The nervous system is a wildly complex and interesting network in the human body. There are over 45 miles of nerves in the average human. This system is important for moving our muscles and also relaying input from our environment up to the brain. The brain is constantly taking in information about temperature, immune system function, hormones, and stretch/tension.
A quick review of very basic nerve conduction: Nerves relay messages by the conduction of an electrical impulse. The nerve must reach a threshold to be activated. It reaches the threshold when enough negatively charged ions enter the nerve through ion channels. This activated nerve than propagates a signal down or up (away from or to the brain).
There are different types of ion channels and the ratio of these ion channels changes every two days. There are ion channels for temperature, immune, hormones, movement, and more. The distribution of these ion channels adjusts to help the brain/body stay up-to-date with current conditions. A change in the ratio of ion channels can make the nerve reach the firing threshold more quickly or slowly. This alerts the brain/body to certain changes in order to respond to environment conditions appropriately.
The most common example of an ion channel affecting pain is during the flu. It is common to be achy all over while you are sick. This does not mean your body has systemic muscular injury. First, the ratio of immune ion sensors has likely increased in your body in response to the flu. Second, the immune system is in high gear to be aware of bacteria/viruses. Third, the increased immune sensors allow more ions to flow into the nerve and the nerve fires more quickly. This means that the nerve reaches the firing threshold more rapidly, making the nervous system more sensitive. Finally, a more sensitive nerve conveys a danger message to the brain more easily.
This danger message can become part of a pain experience.
Changes in Temperature & Ion Channel Response
The same thing can happen with a change in temperature. When the temperature changes, the body could respond with more temperature ion channels. The increase in temperature sensors can make the nerve more sensitive and convey danger messages to the brain more easily.
This does not mean that the pain you are having when the weather changes is “in your head;” this means your ion channels are doing their job and reporting appropriate information to the brain/body regarding the weather change. As a result, the body changes ion channel distribution to improve information it is getting from the environment. In another couple of days the ion channels will likely change again.
What’s the Takeaway?
Next time you or a friend thinks an ache or pain is worse when the weather changes, know that there is physiology backing up that notion. The ion channels change every few days. The nervous system is letting you know the weather is changing. So thank your ion channels and bundle up out there!
Katie Schaner is a physical therapist at CorePhysio and a certified Therapeutic Pain Specialist. She is passionate about helping people get back to the activities they love. Katie is excited to clip on her cross-country skis and hit the frosty trails. She doesn’t let rain, snow, or seasonal aches and pains stop her from moving, and she can help you do the same.
References and resources:
Louw A, Zimney K, O’Hotto C, Hilton S. The clinical application of teaching people about pain. Physiotherapy Theory and Practice. 2016.
International Spine and Pain Institute. www.ispinstitute.com
Pain Guidebook by Greg Lehman available at www.greglehman.ca/pain-science-workbooks