Why do muscles tighten? Almost everyone has excess muscle tension that they’re carrying. It’s a major complaint in chiropractic and massage therapy offices. It’s also the target of most therapies and muscle overuse is almost ubiquitously blamed as being the cause of clients’ pain. However, a muscle only ever contracts if the nervous system tells it to; and the nervous system can just as easily release that contraction and allow the muscle to relax. The question that has to be asked before you ever blame a muscle for being tight is “Why is the nervous system telling that muscle to fire?”. Once that question is answered a much more logical treatment plan can be constructed to resolve the tension that’s been created. There are essentially four reasons why muscles remain in a contracted state. They are:
Nociception, Instability, Poor Brain Function and Psychologic Tension.
We’ll address nociception in this blog. Nociception is often incorrectly thought of as pain signals. However, pain is an output of the brain, not an output of the tissues. Nociception is a stress signal, notifying the brain of potential (or actual) tissue damage. If this signal is strong enough, depending on the context of the signal, you may experience pain. Context is important because if you’re in a war zone, or in a championship game you’ll experience significantly less pain given the same amount of nociception. Nociception has additional effects though, independent of contributing to a pain experience. Even at “sub-pain threshold” levels, nociception has physiologic effects, such as increasing sympathetic nervous system activity (blood pressure, heart rate, sweating) as well as increasing muscle tone. If your low back is being disproportionately stressed due to the way you sit, breathe, lift etc. the levels of nociception from the joints and ligaments of your low back will signal your spinal cord and brain stem to increase muscle tone around your low back to protect it; completely without your knowledge that this is happening. All you feel (if you’re aware enough) is the muscle tension. And when your back does start to hurt, you’ll probably blame it on the tight muscles.
Another very common source of nociception is neural tension. Nerves do not like to be stretched. When they’re stretched it can be extremely painful. When a nerve is stretched it sends a very powerful nociceptive signal to increase muscle tension to prevent any additional stretching. This occurs anytime a nerve is entrapped, and unable to slide and glide across joints and between neighboring tissues. Releasing undiagnosed, or asymptomatic, nerve entrapments is often a very quick way to release muscle tension.
In the following blogs we’ll discuss how instability, poor brain function, and psychologic tension all contribute to excess muscle tone and poor posture.