Rest or Move?

Everything hurts, time to get some rest. My knee feels a bit funny, I’m going to take it easy. My back is sore, I better sit this one out. With this decision I go relax on the couch and watch a nice long movie marathon. The longer I sit, “relaxing”, the stiffer my joints get, and the harder it becomes to get up off the couch that is supposed to be making me feel better. At the end of the evening, I hobble over to go to sleep, wondering why I took the time off.

So why wasn’t my attempt at recovery successful? Everyone needs a rest day, right? What about our body needing time to rejuvenate after hard training? Well, it turns out that when we move, there are several mechanisms at play that help us loosen up and actually heal from injury.

The most obvious one is increased circulation due to physical activity. Blood flow improves with exercise as our blood vessels expand and the heart starts pumping harder. In fact, physical activity is one of the best ways to control high blood pressure. Additionally, the increased amount of blood transports the necessary nutrients throughout the body, such as anti-inflammatory cytokines, that promote tissue repair and healing, reducing muscle soreness.

That’s already a pretty good reason to get moving. Another less obvious reason is the improved flow of lymph throughout the body due to physical activity. The lymphatic system runs along side our veins and arteries, but does not have a central pump similar to the heart. It relies on peristalsis, or contractions in the lymph capillaries, and on compression due to contractions of the nearby skeletal muscles and arteries.

Once again we see that it’s all connected. So more muscle movement and blood flow from physical activity also means better circulation of lymph which is responsible for removing cell waste, absorbing nutrients, and transporting white blood cells for our immune system, thus promoting tissue repair and healing. That’s a pretty big job that is directly aided by us getting moving.

Yet another related mechanism that is activated with movement is the lubrication of joints with synovial fluid. As shown in the image, as the joint moves, the synovial cavity is mechanically squeezed to release synovial fluid that reduces friction and cushions the articular cartilage. This mechanism has another amazing characteristic called rheopexy. The more shearing force is applied to the synovial fluid, the thicker and more viscous it becomes creating more cushion. Any joint in our body that articulates, has this property. In other words, for all the joints we have that move, the more we move them, the more well oiled they get.

Articular cartilage in the knee Joint

Let’s pause here, in awe of the human body. Here are three systems that rely specifically on us being physically active. Given the way our circulatory and lymphatic systems, and our synovial joints are designed, we are guaranteed to get more stiff and sore if we sit around, and to feel better and heal faster if we go for a walk. I’d call that a pretty good return on investment.

So in practical terms, if you planned to go to the gym but are feeling too tired, can you still go, modifying the workout to stay consistent? If your knee feels funny, how can you work around it? Can you find activities that don’t aggravate it, but still get you moving? If you’ve trained a lot of jiu jitsu, and your back hurts, can you still go to class and drill techniques, but not spar? Or if you need a mental break, can you go do something else that still keeps you active?

Takeaways

  • The more we move, the better our blood flow gets, contributing to overall health and reduced muscle soreness
  • The more we move, the better our lymph circulates, promoting healing and a stronger immune system
  • The more we move, the more lubricated and less stiff our joints get
  • Being active helps us feel better faster

Comment below if you’ve experienced being sore and stiff only to feel much better after some physical activity. What are some of your favorite ways to get moving?