by Nikhil Ramburn and Sat Bir S. Khalsa, Ph.D.
Osteoporosis is the degeneration of bone tissue that occurs when new bone creation doesn’t keep up with the body’s natural process of old bone removal. Individuals may experience a decrease in height over time and localized pain, but many people have no symptoms until they experience a bone fracture. Women are more likely to develop osteoporosis, and a reduction in estrogen levels in women at menopause is one of the strongest risk factors for developing osteoporosis. Other risk factors include a diet low in calcium, obesity, comorbid inflammatory conditions such as Lupus and Rheumatoid Arthritis, and a sedentary lifestyle. Osteoporosis is considered a serious public health concern given that over 200 million people worldwide suffer from this disease, and approximately 30 percent of all postmenopausal women have osteoporosis in the United States.
Conventional pharmacotherapy includes bisphosphonates, a class of drugs for preventing bone density loss, although these have possible side effects including gastrointestinal toxicity, death of bone tissue in the jaw and other sites, and severe (and sometimes irreversible) leg cramps and bone pain. However, bone density is sensitive and responsive to physical activity. Numerous, controlled studies have demonstrated that people who exercise regularly have greater bone density than their sedentary counterparts. Resistance training and weight-bearing exercises can help slow down bone loss in part due to the dynamic loads delivered to the skeleton, which stimulates the deposition of more bone tissue. In addition, a diet containing green leafy vegetables along with nuts and legumes can provide the necessary calcium to reduce the risk of osteoporosis.
Complementary and integrative approaches such as yoga may offer many of the benefits of conventional exercise, while also enhancing balance, posture, flexibility, strength, and quality of life in the elderly. Indeed, yoga exercises may decrease fall risks and fractures because of their positive effects on balance. In addition, the ability to modify yoga exercises to accommodate individuals with a high risk of falls or fractures and who have limited strength makes this intervention particularly suitable to elderly osteoporotic patients. The combination of mild spinal flexion and extension, which are common within yoga practices, may decrease the risk for vertebral compression fractures whereas the moderate weight-bearing exercises in yoga can strengthen the core muscles that support the spine. A small 2009 feasibility pilot study found that markers of bone formation increased in osteogenic postmenopausal women after a 12-week yoga series, thereby indicating that yoga may have beneficial bone building effects in this group. Furthermore, a 2012 study at the University of Calgary investigated the reaction forces applied by Hatha yoga practitioners for the first time. The researchers found that a common 28-posture sequence applied a low impact Ground Reaction Force (GRF) to upper and lower extremities; however, further research is necessary to determine whether those forces are sufficient to maintain current bone health in yoga practitioners.
Preliminary biomedical research on the efficacy of yoga for osteoporosis is promising. In a single-group pilot study at the Columbia College of Physicians and Surgeons in New York in 2009, patients with osteoporosis or osteopenia (lower bone density than normal but not yet pathological) practiced a regimen of 10 yoga postures which were modified according to individual limitations. The poses included the triangle pose (Trikonasana), the upward and downward dog poses (Adho Mukha Svanasana and Urdhva Mukha Svanasana) amongst others. Each position was held for 20 to 30 seconds. Unfortunately, compliance was poor and only 11 patients out of 117 completed the 2-year protocol. Nevertheless, the results revealed statistically significant improvements in bone density scores in yoga practitioners, 5 patients with osteopenia were reclassified as normal, and 2 patients with osteoporosis were reclassified/downgraded to as osteopenia, thereby indicating that yoga exercises for as little as 8 to 10 minutes daily will increase bone density in older patients.
A subsequent study with a larger sample size was published in 2016 and documented a 10-year study of 741 internet-recruited volunteers. Participants used a 12-minute DVD of the yoga poses that would stimulate bone density (the same exercises from the pilot study described above). The poses were specifically selected to produce torque and bending of the proximal femur, compression of the pelvis, and twisting of the lumbar vertebral bodies as these are the most common sites of osteoporotic fractures. The researchers found that bone mineral density improved in hips, spine, and femur in the 227 moderately and fully compliant patients. In fact, monthly gain in bone density scores was significant in both the spine and femur while gains in hip bone density did not achieve statistical significance. Furthermore, no yoga-related injuries were imaged or reported. This current study therefore supports the efficacy and safety of yoga as a treatment for osteopenia and osteoporosis.
Another landmark study was a 5-year retrospective evaluation of Bikram Yoga in a select group of female Bikram Yoga instructors that had been practicing for at least three years and some for over 20 years. While high impact exercises can improve bone health, those same exercises are also well-documented to damage the hip and knee joints. The researchers therefore set out to ascertain whether the potential benefits of low impact weight-bearing Bikram Yoga exercises could offset those deleterious effects. The participants routinely did 4.5 hours of yoga a week but also actively taught yoga classes where they modeled the correct poses. These same participants, who remained active as instructors and practitioners, were scanned five years later. The researchers found that the premenopausal subjects showed an increase in bone density scores at the femoral neck, hip, and lumbar spine. In contrast, there was a decrease in bone mineral density in those same areas for post-menopausal subjects. Consequently, these results suggest that Bikram Yoga may be an effective countermeasure for preventing osteoporosis in pre-menopausal women but may not necessarily confer the same benefits to postmenopausal women.
More recently, researchers from the Bone Density Research Laboratory at the University of Oklahoma looked at the effects of an 8-month Ashtanga Yoga intervention on middle-aged premenopausal women using a randomized control design, the gold standard of scientific research. Thirty-four premenopausal women were randomly assigned to either a Yoga group (n = 16) or a control group (n = 18). The participants performed 60 minutes of an Ashtanga Yoga series including 15 minutes of warm- up exercises, 35 minutes of Yoga postures and 10 minutes of cool-down. After 8 months, the researchers found that serum markers of bone growth were maintained in the yoga group but significantly decreased in control subjects. On the other hand, no improvements in bone mineral density or tibia bone characteristics were noted. Therefore, these results suggest that regular, long-term Ashtanga Yoga had a small positive effect on bone formation.
In summary, the current body of evidence points towards increased bone mineral density with yoga practice, suggests improvements in serum markers of bone growth, and even demonstrates the potential for yoga to reverse bone loss that has reached the stages of osteopenia and osteoporosis. However, additional studies with larger randomized controlled trials and further investigation including a younger osteopenia-free population are necessary to support these findings and establish the benefits of yoga in relation to conventional exercises. Finally, some researchers warn that new pain and fractures can occur after participation in yoga flexion exercises given the extreme strain of some yoga positions. An assessment of fracture risk in older persons is critical in designing an effective and safe therapeutic yoga intervention.