Why do muscles get sore after long periods of inactivity, like quarantine?
In: Biology
I have read two hypotheses on this. They both focus on the idea that unused muscles are recycled by the body and shrink in size, a process called atrophy. One explanation is that muscles are connected to the brain by nerves, and when you lose some muscle tissue, you’ve disrupted a nerve connection that your brain is used to being there. Some nerves that make muscles contract also convey sensory information, and the disrupted nerve signal reads as pain. Something kinda-sorta like this can happen when someone loses a limb.
Another explanation is that atrophied muscle can cause the release of cell contents into the space between the cells that remain. Some of these molecules interact with the nearby nerve cells and cause pain. This type of discomfort is known to occur when you don’t work out for a long time and then hit the gym too hard, and goes by the name of Delayed Onset Muscle Soreness, but it is close to the same mechanism.
If someone has a more definitive understanding, I’m interested in learning more as well.
In a very general sense, your muscles shouldn’t be getting sore after being inactive. However, there are reasons they could become sore, stiff, or otherwise uncomfortable.
You don’t ask much in the way of specifics, so I’ll do my best to guess what you are experiencing. If it’s muscle stiffness in the low back, shoulders, or even some areas of the limbs… the likely culprit is poor posture. I’m not talking just about standing or sitting upright.. but also sleeping, chores, etc. There are ways of moving (or in this case not moving) that are simply better for you.
For a visual example.. imagine you buy a couch. When you first buy it.. everything feels nice, every spot is pretty much the same soft feeling, every cushion reacts the same way when you sit down on it. Over time, you find that spot that you like. You sit on that same spot over the months and years and now that spot is wearing out. The springs are stiff or broken, the cushion stuffing is disproportionally placed around where you sit, and the other spots just don’t feel the same.
The same goes for your body, but it’s not about where you personally sit. It’s about where the load (stress) of your bodyweight sits on your body. In a low back example.. lets say you sit on a chair for 4 hours. We all have a decent image in our mind of what proper posture looks like. While the image you think of is probably not exactly correct, it’s close. The problem is we don’t usually follow it. Instead we allow our upper body to slouch and we round our lower back (backwards).
The spine and muscles of the spine are oriented in a very particular way for proper load distribution. When we sit with bad posture, this orientation is disturbed and one side has to make up all of the extra work. Over time (in this case hours / days rather than months / years) the muscles get tired and probably inflamed. Inflammation is a painful signal, but it’s to get you to stop using those muscles so they can repair.
It may not sound like a sitting with a bit of a rounded back can apply all that much extra stress, but the pressures and strengths of these muscles is more than you think. Even doing something like a crunch exercise can put many hundreds of pounds of stress on one side of the spine that isn’t applied to the other side. This is due to a variety of physics things I won’t go into like moment arms.
The key is to do everyday activites with good posture. This balances the load, which can drastically reduce stress and tension for muscle groups (and joints!). For the shoulders and stuff.. the simple relaxing the shoulders down and back works pretty well. The low back is.. less intuitive.. I won’t bore you to death with it.. but finding a good lumbar support to keep the shape of the natural curvature of the spine should help a lot.
On the other hand.. if it’s soreness after starting to do things again after being inactive. That’s delayed onset muscle soreness (DOMS). While typically associated with exercise, any new movement can cause it. The muscle cells are ripped apart and this causes inflammation and pain for the next few days. It doesn’t happen right away as not all of the signaling and repair processes begin immediately (probs wouldn’t bode well for early survival), so usually the pain doesn’t show up for a few hours or until the next day.
If that’s the case, just getting back into the habit of being active and your muscles adapting to the new stress is needed. Does take a bit of time.. up to as long as 4 -8 weeks, but usually only a week or so for a new light activity.
My case is the first. I have an old bed because I can’t afford a new one. So the springs and stuff have worn out where I like to sleep at.. my back flattens, losing it’s natural curve which puts stress on the postural muscles of the spine overnight. A new bed with better form fitting would help a lot. I could do some other ways of fixing it if it gets bad enough.. putting a towel under my low back to help keep the curve. Pillow under the knees, etc.
If neither of those are your issues. I need more specifics.
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