How anxiety causes muscle tension, and vice versa
We’ve already learned that anxiety causes our natural stress response to be constantly activated, and that our muscles contract as part of our stress response. When we experience anxiety, our neuromuscular system never gets a chance to recover or return to normal. Our heart rate remains elevated and our muscles retain a higher than normal level of tension.
Here’s a quick lesson on what’s happening in your muscles when they’re tense all the time:
When our muscles are constantly contracted, our cells are forced to create energy for our muscles through the process of anaerobic metabolism. In this process, glucose is synthesized into adenosine triphosphate (ATP) without the help of oxygen, and lactic acid is produced as waste.
Lactic acid is often blamed for muscle soreness, but actually, our body quickly breaks down lactic acid into lactate and hydrogen ions. A buildup of hydrogen ions, which activate our pain receptors, is likely the cause of the dull ache and burning sensation we feel in our muscles during strenuous exercise.
And a buildup of lactate is linked to anxiety. Not surprisingly, studies show that people with anxiety have higher resting levels of muscle tension, react to stress with stronger muscle contractions, and return to their baseline level of tension more slowly than control subjects. As a result of their increased muscle tension, levels of lactate in the blood are higher in anxiety patients.
But what is quite interesting is that this physiological loop goes both ways. We can actually make ourselves anxious, and even induce panic attacks, by injecting lactate into our bloodstream. So not only does anxiety increase muscle tension, but chronic muscular contraction and increased lactate levels can cause anxiety, creating a vicious cycle.
Perfectly healthy people experience increased muscle tension when they feel stress. One study found that simply having to complete word and math problems in a research lab increased the muscle tension of test subjects. In another experiment, subjects were given a picture and asked to tell a story about it. While they told their stories, their muscle tension increased because they experienced a little bit of anxiety, just as most of us would when performing in front of other people. When they finished, half of the subjects were praised for doing a good job on the task. Their muscle tension dropped back to normal levels. The other half of the subjects were criticized for their poor performance, and their muscle tension remained higher than normal—until they were reassured by a different researcher that they had actually done a good job.
Mental activity alone, not just psychological stress, is enough to increase muscle tension. Edmund Jacobson, a physician and psychologist, conducted a number of studies in the 1920s and 1930s using an electromyograph (EMG) to observe the correlation between thought and muscle tension. He developed a technique called “progressive relaxation” to guide his subjects through a process of contracting and releasing their muscles one by one. As the subjects’ muscular tension decreased, their mental activity decreased as well. Once relaxed, it was quite easy to see the elevations in muscle tension that occurred when the subjects were instructed to think about specific things.
Jacobson’s research proved that mental activity always occurred along with an increase in muscular tension, and that reducing muscle tension had the immediate effect of decreasing mental activity and the overall activity of the central nervous system.
Our level of psychological stress and the way that we process it exists on a spectrum. A moderate amount of worry triggers our stress response to a lesser degree than a diagnosable anxiety condition would. Unfortunately, it’s surprisingly easy to get used to an increased level of muscle tension and heart rate and to be completely unaware that your baseline level of stress is elevated.