Last updated: March 20, 2020
This concern generally takes the form
Stressing of joints is dangerous because the joints can be taken too far and become hyperextended. The only way to prevent damage to a joint is to make sure that the muscles surrounding the joint are engaged so that they take the stress, not the joint. Do not relax your muscles when you are stressing a joint!
Rather than create fear and say that “stressing of joints is dangerous,” it is far better to say, “stressing of a joint could be dangerous, but it is not always dangerous, and most of the time it is required for the joint to be healthy.”
All tissues require stress to regain and maintain optimal health (see the article on Antifragility), and this includes our joints. They need stress, which can also be called load, or exercise. Part of the fear surrounding exercising joints is confusion over the two types of exercises we use to stress tissues: exercises can be either dynamic and active, or passive and static. If we apply an active, dynamic stress to our joints, there is a possibility of destabilizing the joint capsule, in the same way that bending a credit card back and forth repeatedly weakens the plastic. When subjected to this type of stress, it makes sense to co-contract the muscles around a joint, which is protective. However, Yin Yoga does not employ dynamic stress; it employs passive, static, long-held stresses, and this type of stress has been found to be therapeutic for joints.
Yin Yoga for healthy joints
“Use it or lose it.” This common saying speaks to what happens when you don’t stress your joints. When a healthy joint is deprived of stress, it undergoes contracture. Contracture results in a loss of mobility. There are many causes of contracture: illness, nerve damage, muscle atrophy, or problems with the joint’s cartilage or ligaments. Laurence Dahners of the University of North Carolina lead a team investigating this question and discovered a mechanism whereby the body shrink-wraps our joints when they are not stressed. He noted, “A common clinical finding is that unloaded ligaments not only atrophy, but also undergo contracture.”
An example of shrink-wrapping contracture is the classic frozen shoulder syndrome. For example: Grandma falls and breaks her arm, the bone is reset, and the arm rests in a sling for several weeks. When the time comes, the sling is removed and the bone has healed, but grandma’s shoulder is frozen. What happened? While there are multiple causes of frozen shoulder syndrome, this cause was the lack of use of the shoulder joint. The body took away materials no longer needed or used, contracting the joint and shrinking the joint capsule. When the time came to use the shoulder again, it couldn’t respond.
Professor Dahners’s studies have shown that joints need stress to be healthy. But, what kind of stress is best? To answer that, we can turn to studies of how damaged joints heal through stress.
Yin Yoga for damaged joints
Passive, long-held, non-maximal stresses have been found to enhance damaged joints’ lost range of motion with minimal or no tissue damage. The type of stress employed in these therapies is identical to the quality and quantity of stress applied in Yin Yoga.
One study of contracture repair concluded that “the clinician’s ideal treatment program for a patient with passive joint limitation should be mild stretching [of the joint], as much as is practical throughout the 24-hour day, 7 days a week, and to start this program as soon as joint motion is allowed.” This study showed that it is not only safe to stress or exercise our joints, it is required, and that the stress should be passive. The study contrasted short, intense stresses like we find in a yang yoga practice with long-held, mild stresses like we find in a Yin Yoga practice. The researchers concluded “the longest period of low force stretch produces the greatest amount of permanent elongation, with the least amount of trauma and structural weakening of the connective tissues. Consequently, permanent elongation of connective tissue results in range of motion increases for the patient.” The shorter, more intense stresses were observed to have resulted in “a higher proportion of elastic response, less remodeling, and greater trauma and weakening of the tissue.”
In other words, longer holds of less intense force work better for regaining lost range of motion within a joint with the least amount of tissue trauma, and that is our prescription for Yin Yoga practice.
Yin-like therapy for the joints are beneficial
One final therapy for joints is worth noting. It is called static progressive stretch, or SPS for short. SPS is one of a group of therapeutic interventions used to help patients regain lost joint range of motion while decreasing pain, stiffness and swelling. It is used with patients who have undergone surgery or trauma that required immobilization of a joint. The immobilization may have been necessary to protect the joint from excessive stress during the initial healing phase, but immobilization can lead to significant complications and pathologies, including contracture of the joint as just observed.
To recover lost range of motion, the first option is to use physical therapy to passively stretch the joint with progressively greater loads of force to take the joint beyond its limited range of motion. (We can consider this therapy to be a form of Yin Yoga being done on the client rather than by the client.) However, physical therapy is limited in the number and duration of sessions. You can only visit your therapist so many times a week, and certainly not 3 or 4 times every day. Thus stretching devices may be considered as an adjunct to, or in place of, physical therapy.
There are several possible devices that can be used, but of interest is static progress stretch (SPS), which is like Yin Yoga being done by the client on herself. With these devices the joint is taken to its tolerable limit of movement for a period of time. Once the sensation ebbs, the patient then is free to increase the stress, taking the joint to a new edge, and again hold there. Through this progressive approach, at each setting the joint is subjected to a constant level of stretch, and as the joint is held at this position, the stress level within the tissues lessens. Thus we have the name static progressive stretch. These devices have been used for restrictions in mobility of ankles, knees, shoulders, elbows and wrists.
There are interesting correlations to Yin Yoga in the way SPS devices are used:
- The stress is static and passive, which is the same in Yin Yoga: we don’t continually move and the muscles are not used to create the stress.
- A tolerable depth is obtained.
- The duration of the stress is on the order of 30 minutes. In a Yin Yoga class, we do not hold any one particular posture that long, but throughout the whole class, the cumulative time spent stressing a particular joint could be 15~30 minutes.
- If the sensations decrease, the patient decides to go deeper and adjusts the device to allow more range of movement; in the same way, in Yin Yoga the student controls the depth in a pose. If the sensations ebb away (the edge “moves”) then the student allows herself to go deeper.
In short: All tissues need stress to be healthy and our joints are no exception. However, the best way to stress yin-like tissues, such as our joint capsules and ligaments, is with a yin-like stress: a long-held, passive, non-maximum stress. Several therapies employ exactly this kind of stress to heal damaged joints. It is possible to go too far and over-exercise joints, or any tissues, but this must not be confused with never stressing them. Unstressed joints lead to contracture and atrophy. Joints need stress and yin stresses have been proven to be healthy and protective. It is okay to do Yin Yoga on your joints, as long as you practice with intention and attention.
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 Laurence Dahners, “On Changes in Length of Dense Collagenous Tissues: Growth and Contracture,” Laury Dahners’ Orthopedic Page (accessed January 10, 2020). https://laury.dahners.com/assets/documents/orthopedic/KD%20paper%20for%20web%202020.pdf
 George R. Hepburn, “Case Studies: Contracture and Stiff Joint Management with Dynasplint,” Journal of Orthopaedic and Sports Physical Therapy 8.10 (April 1987): 498–504. doi:10.2519/ jospt.19126.96.36.1998.
 Other devices include serial casting, static braces, or dynamic splints that provide low-load, prolonged stretch. Dynamic splints use spring loading or elastic bands to provide low-intensity tension (less than that exerted by a physical therapist) and are designed to be worn over relatively long periods (for example, 6 to 8 hours at a time or overnight). With these devices the angle of the joint may slowly change over time. With an SPS orthosis, the angle of the joint remains constant until the patient resets it, and the device is generally only worn for up to 30 minutes at one time.