How do your muscles protect your joints from injury and wear and tear?
If someone has arthritis in a joint, is there anything that you can do to help?
Will muscle strengthening help the joint?
When there is pain around a joint, your instinct may be to protect your joints by limiting your movement, but that usually leads to a downward spiral of disuse, weakening and further pain. But the joints themselves are nourished and lubricated by movement and firing muscles will keep the support structures around the joint healthy. A popular saying in rehabilitation is “motion is lotion.”
Muscles are sometimes thought of as guy wires or springs and though this isn’t exactly how they operate at the muscle cell level (they only contract they don’t push back), functionally they do behave like guy wires and springs.
Think of how muscles and tendons operate together. When we run or jump the Achilles tendon stores energy as it is stretched and releases energy when we push-off or jump. So with this in mind, let’s begin by examine the leg muscles.
When you walk, run or squat, there are muscles on either side of the knee and hip that contract at the same time, allowing you to move, but also provide support and cushioning to the joint as well. In fact all the muscles that surround the joint, under normal circumstances, will fire to support optimal alignment and create movement.
However, because of injury, pain or disuse muscles can weaken and not fire optimally or in a coordinated way. By strengthening the muscles around the joint you can provide spring-like protective support, and therefore a greater proportion of the body weight will be absorbed by the muscles instead of the joint.
Looking at the spine we see that in cadaver studies, the spine with discs and ligaments intact (but no muscles) can only withstand about 20 pounds of compressive force before it buckles. That means that the spine is inherently not very stable. The activation of the core muscles provides the support for the trunk so it is able to withstand forces of even hundreds of pounds of force in some athletes without harming the spine itself.
However, the spine can withstand fairly high forces even with low to modest force of muscle activation.
That means that heavy strength training for the trunk muscles is not required for the vast majority of people, even athletes. What is required is a combination of moderate strength and endurance (the ability to contract at low levels for a long period of time).
When the spine or trunk muscles are injured it is usually a problem of firing the muscles (‘motor control’) in the proper way as well as the positioning of the spine in its neutral posture.
This explains why you can suffer a back injury by just bending over and picking up a pencil. It’s not so much the weight of the object, it’s how you control the muscles firing around the spine that count.
Even though strengthening is almost always beneficial, care must be taken to assure proper alignment is achieved while strengthening, because you don’t want to be reinforcing poor joint positioning while exercising as this can irritate a joint.
There may be many exercises that are off-limits for people with a particular type of arthritis or when joints are swollen and inflamed. The amount and form of exercise recommended for each individual will vary depending on various issues including the type of arthritis, the specific joint in question, level of stability or inflammation or whether the person has a joint replacement. A therapist prescribing strengthening exercises should take these issues into account.
Discuss your specific conditions and goals with your family doctor so they can make the necessary recommendations for treatment.
Kerry Senchyna holds a bachelor of science
degree in kinesiology and is owner of West Coast Kinesiology in Maple Ridge.
