This is a real problem for a lot of people – delayed pain.
If you have, for example, knee pain from Patellofemoral Pain Syndrome, Chondromalacia, or Degenerative Joint Disease and it’s a mild case, meaning that you can do everyday activities like just walking around without symptoms, you might think you’re fit enough to go for a run.
So, you do.
And, things seem to go well until about two days later.
What we all do is look back in time about twenty-four hours from the onset of pain and, within that time span, we search for any evidence that supports our current situation.
One of my clients was absolutely convinced that his increase in knee pain was from performing quad sets – an exercise with extremely low joint loads – when actually, he had drastically increased his daily activity, the amount of walking, climbing stairs, etc., a couple of days prior. Even though this translated into thousands of pounds of extra force, because the offending activity was so far removed from the present, he couldn’t see the connection. So, he concluded that a low joint load exercise of about 50 reps was the cause of his knee pain.
One of the reasons that joint pain is often delayed is that the message travels on a slower nerve pathway, Type C Fiber, than more acute pain. If I pinch your skin really hard, you’ll hurt right away. But joint overload is cumulative and the pain mechanisms are different. It can be anywhere from six to 48 hours, even 72 hours, before you notice the pain.
Remember, your joint cartilage doesn’t have any nerve fiber in it. So, as the forces exceed the joint surface capacity, those forces get absorbed by the synovium, bone, ligaments, tendons, and joint capsule. The pain receptors are slow to respond in these tissues because you load them everyday over a variety of functions. You need to be able to do things without hurting all the time. If the receptors in these tissues had low thresholds or were easy to stimulate, you would hurt a lot and a lot of the time.
In fact, one of the problems of joint inflammation is a lowering of the threshold of these receptors. (Think about how much your finger hurts when you have a sliver of wood in it.) This makes it easier for everyday activity to become painful for some people.
When you think about it, the design of the joint is smart.
Imagine how much you would hurt if your cartilage actually had nerve fiber in it?
Delayed pain is why, when you return to running, you have to do so in a more structured and careful way. Otherwise, you’re more apt to re-injure yourself and getting healthy and fit will be very difficult to do.