Yoga

The Science of Yoga

IIHW member George Salem collaborated with National Center for Complementary and Integrative Health (NCCIH) to provide a deeper understanding about the science of yoga. The official NCCIH article can be found here.

Q & A With Drs. Gale Greendale and George Salem

Source: NIH | Original article can be found here.

Q1. Yoga practice is prevalent across the United States. Yoga is taught in many cities in private studios, community centers, gyms, and physical fitness facilities. There is a general perception that yoga is safe. Are there safety issues to consider when practicing yoga? In particular, is it safe for older adults?

Answer: Like other forms of movement, yoga is safe in older persons if certain conditions are met. The level of the activity (e.g. intensity, balance demands, range of motion required) must be properly matched to the yoga practitioner.

Thus, we must take care to “get it right” when teaching yoga to seniors. Compared to younger adults, in general, older adults have less strength, range-of-motion, and balance. With age, we also have more “medical baggage,” (conditions such as osteoarthritis, heart disease, diabetes, etc.) that play into pose selection and modification.

We are currently conducting research into how to maximize yoga’s safety in seniors. But, how can we maximize safety of yoga in seniors in real time while that research is ongoing? The following suggestions are based on our clinical and research experience to date. Prior to beginning a yoga program, older adults should see their primary care provider to get advice on any restrictions or special advice pertaining to their health. Then the yoga student should inform the yoga instructor, so that he/she is aware of any relevant conditions.

From the yoga instructor’s perspective, heightened attention to safety and more intense supervision is paramount when teaching seniors. Because seniors have reduced sensory feedback capabilities and many have not participated in movement programs for some time, they can potentially put themselves into postures that they are not capable of safely performing. With respect to asana (pose) selection, the traditional poses should be modified in order to reduce the risk of injury. Our study provides biomechanical evidence to help instructors select appropriate poses and pose modifications for this purpose.

Q2. What is the focus of your NCCAM-funded research, and what are the main findings?

Q2a: Are there some yoga postures (“asanas”) that may be problematic for some adults? Is there any way to know in advance whether someone shouldn’t perform a given posture?

The YESS study characterized the physical demands of 22 yoga poses and pose variations in a sample of older adults who had been trained for 32 weeks. We found statistically significant differences in the Joint Moments of Force (JMOF; a measure of the muscular and joint demands of an activity) that were generated among the poses, across all joints examined. Our findings were not always intuitive and suggested that some long-held conceptions regarding pose demands and pose modifications may not be correct (e.g. tree, warrior II, and one-legged balance poses). These findings may be used to better design and tailor yoga programs to the physical capabilities of the senior practitioner, in order to increase the benefits of yoga participation and decrease injury risk. A secondary aim of the study was to examine the strength, functional performance and balance changes that occurred following the 32-week program. Our findings suggest that yoga improves physical performance in several areas including the ability to stand from a chair, rise up on your toes, and march in place. Knee flexor strength was also increased but knee extensor and hip abductor strength did not change. Balance and self-selected walking speed also did not change.

Based on the YESS results, two major areas were potential “danger zones” in seniors. Before we describe these, it is critically important to note that our study was conducted in ambulatory seniors who did not use assistive devices, who could get up and down from the floor, who could lift their arms to shoulder height and who could stand with good balance with feet side-by side. Trouble spots would be different (no-doubt greater) in seniors with more limitations.

The shoulder needs special attention. The most common problem reported in YESS (about 1/3 of subjects) was shoulder pain, despite the fact we advised participants not to exceed their comfortable range of motion and took care to supervise them very closely. Based on this experience, we believe that shoulder flexion (roughly, shoulder flexion means raising arms toward the head) should be limited in senior yoga. Based on YESS and other work in seniors (the Yoga for Kyphosis Study) we hypothesize that extreme shoulder flexion may lead to impingement syndromes. Moreover, poses with extreme flexion angles may also generate high joint torques which may be associated with overuse injuries.

The low back can be a problem area. Another common problem in YESS and in the Yoga for Kyphosis study was low back sensitivity, again despite the fact that we modified the postures to try to avoid excessive back bending at the outset and we carefully supervised the students. Our research suggests that the culprit here was excessive back extension in the lumbar region (that is, too much back-bending).

Our future research will work on how best to modify the shoulder positions for the common asanas and how to modify poses that call for back-bending. The YESS Web site shows some modifications to shoulder positions that may be useful (Article Link).

In addition to these two particular trouble spots, the pre-Yoga evaluation by the student’s primary care provider is very important. Findings from this evaluation will alert seniors (and by extension, their teachers) to existing conditions that require care during practice.

Q2b: Is it all about torque (i.e., the “load” on a joint), or is it also about duration?

The torque or moment that is created about the joint is an indirect measure of the muscular and ligamentous demands at the joint. These demands typically vary over the duration of an activity (e.g. bending into and coming out of the warrior poses). It will also depend on how long the student is “holding the pose” (that is, maintaining an isometric contraction).

Thus, in order to get a full picture of the physical demands of an activity it is important to consider both the magnitude and duration of the joint torques. A measure which captures both of these characteristics is impulse (quantified as the sum of the joint torques over time).

Q3. What is biomechanics, and how was this field utilized in your study?

Answer: Biomechanics is the study of the physical properties of biological systems. Kinesiologists, exercise scientists, and neuroscientists (along with a host of other researchers) use this discipline to study and quantify the physical attributes of human movement. That is what we did in the YESS study…we used biomechanical investigation (motion analysis with high-speed cameras & force platforms, and electromyography—a measure of muscle activation) to quantify the physical demands (joint angles, joint moments/torques, and muscle recruitment patterns) of yoga poses (asanas) used in a 32-week yoga intervention for seniors. We also used this type of analysis to quantify some of the adaptations (walking speed, balance capabilities) associated with the intervention.

Q4. What is your vision for the integration of yoga into physical therapy practice?

Answer: We believe that information from our study and future studies in other cohorts (younger adults and persons with disability) will be used by physical therapists to design rehabilitation protocols that include yoga as a therapeutic intervention. For example, physical therapists can use the biomechanical profiles we created to select individual poses for their patients that target weak muscle groups or unload structures at risk for further injury (e.g., sprained ligament). These poses can then be integrated with other exercise activities and physical therapy modalities to provide a more holistic (and perhaps fun) approach to patient management.

We also believe that evidenced-based yoga programs will be developed for patients once they have exhausted their number of insured therapy visits, so that they can continue to rehabilitate in a safe, structured, environment. The USC Division of Biokinesiology and Physical Therapy, is committed to promoting the integration of evidenced-based complementary and alternative medicine modalities (including yoga) into traditional physical therapy practice, and we have established a new center, the Center for Integrative Rehabilitation, to support this initiative. Together with other researchers and faculty members from USC and UCLA, the center will use rigorous scientific study, clinical implementation, and new curricula to expand the integration of complementary and alternative medicine in physical therapy practice.

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