Chronic Back Pain: Muscle Flexibility, Strength, and Endurance


The best way to decrease the peripheral pain signals is to make sure that the muscles are working at their best. Muscles have three main properties. These include flexibility, strength and endurance. Any change from having sufficient flexibility, strength or endurance can cause your muscle pain receptors to start firing and telling your spinal cord something is wrong.

First, muscles must have enough flexibility or “stretchiness.” One way to think of muscles and tendons is to compare them with rubber bands. When we are young, muscles and tendons have natural elastic properties; children and teenagers frequently do not have chronic pain. The stretching exercises taught in physical education classes are intended to encourage a lifelong habit of stretching and maintaining flexibility. As we get older, we lose these elastic properties and lose some flexibility. This also explains why we get wrinkles on our skin. People who have had poor flexibility all their lives or who do not exercise are especially at risk for developing back pain; inevitably their neglect of stretching catches up with them and adds to the natural aging process. When a short, tightened muscle is stretched, pain receptors within the muscles naturally respond to alert the spinal cord of this abnormal signal.

The easiest test to see if your flexibility is causing your back pain is simply to sit in a chair and cross one leg over the other and bend your trunk forward. If this reproduces some of your pain, there is a high likelihood that muscle inflexibility is at least a treatable component of your pain. Do this on with your other leg and see if there is a difference. If there is a noticeable difference from side to side, that means the muscles on your painful side are probably shorter than the muscles on your non-painful side.

Next, muscles must have enough strength to be able to generate enough force to control our joints while we walk. Our gluteal (buttock) muscles must generate enough force to control our pelvis while standing on one leg. This concept is something we all learned when we were a year old and learned to walk. We figured out that if we can stabilize our hip, we can put all of our weight over that one leg. If we stabilized the other hip, we could take another step. By repeating this process, we learned how to walk.

People Asset Index

Another important thing to remember is that our muscles are accustomed to moving only our current weight. If you gain an extra 50 lbs, those buttock muscles have a much harder job to control your hip and are more prone to being strained or injured with sudden or unexpected activity. Even slight gains in weight may lead muscles that were previously barely able to compensate without back pain to become painful. Keep an eye on your weight and do what you can to maintain a healthy weight and a regular exercise program.

It is also helpful to consider horsepower to weight ratio, factors important for airplanes to take off properly or sports cars to accelerate quickly. Weight itself is not necessarily a factor if you have enough power to move it. Some professional athletes or football players can weigh over 300 lb. However, their muscle power is more than enough to allow them to work at a high level. People who have heavy work demands need to make sure their muscles are operating at 100% efficiency. We do not know at this time what the ideal horsepower to weight ratio in human beings needs to be to combat back pain. However, a person who weighs 250 pounds needs stronger muscles to function than a person who weighs 150 pounds. Increasing muscle power is especially important for easing back pain, and especially important if your muscles must carry additional body weight.

Third, muscles must have sufficient endurance, or the ability to be strong over a period of time. Usually if a person does not have even enough flexibility or strength to start activity, then having endurance to continue the activity is even less likely. A regular cardiovascular or aerobic exercise program is essential. As we age, our endurance can diminish. This may explain why many Olympic athletes are rarely able to perform at age 40 at the same level as when they were at age 20. What was an easy workout when we were 20 years old becomes much more difficult at age 40 if we have not maintained the same exercise program over the intervening 20 years. It doesn’t matter whether a person walks, runs, swims or bicycles; what matters is a consistent record of activity. This is the currency that your muscles understand. This is a bank you can’t keep borrowing from without contributing to on a regular basis.

Many people with chronic back pain tell us that they are already doing exercise. In that case, what your back pain is telling you is that your exercise program is still not sufficient to control your body’s muscles and current weight requirements. We recommend you increase your exercise regimen even more for another 6-12 weeks and see if your new exercise program allows your muscles to function with less pain. If you still have pain then, you’ll likely need to do even more exercise. Talking with a physical therapist or physician at that time may be a reasonable plan. Your muscles only understand recent activity. Don’t exercise for us. Exercise for your own muscles’ health and well-being.

Grey Muscle Area

We’ve discussed several possible reasons why inflexible, weak, or deconditioned muscles could be causing some of your chronic back pain. Does this sound reasonable? Do you have pain over those particular muscle groups? The typical muscle groups that cause pain are the gluteals, lumbar paraspinals, quadratus lumborum and spinal multifidi muscles (shaded areas, left).


Sometimes people don’t believe that their pain can be coming from their muscles because it is so “deep.” Many muscles are quite deep and because they attach to bones, their pain can feel like pain “coming from deep within the bone.”