Yoga has long been associated with a host of health benefits - and it may even boost physical capabilities associated with longevity, new research suggests.
A systematic review by Brigham and Women's Hospital in Boston published in the Annals of Internal Medicine this week found that yoga improves health indicators linked to reduced frailty and increased longevity in older adults. Looking at 33 randomized controlled trials across 12 countries involving more than 2,000 participants, researchers determined with "moderate certainty" that doing yoga improved certain frailty markers including walking speed, lower extremity strength and endurance.
Julia Loewenthal, a geriatrician at Brigham and Women's Hospital who was involved in the research, said this was significant because many frailty markers are "connected with clinically meaningful outcomes like living independently and mortality." She said she hopes older adults will be "encouraged by this research and empowered to adopt a regimen that works for them."
Yoga incorporates physical poses, breathing and meditation, and previous studies have looked at how it can improve balance and mobility, physical function and mental well-being in older adults. The authors of the Brigham review say it is the first to examine the effects of yoga on frailty - a multifaceted, difficult-to-treat health condition associated with increased falls, hospitalization and morbidity that is at the forefront of public health concerns as countries around the world deal with rapidly aging populations.
Frailty affects 7 to 12 percent of people over age 65 in the United States, according to the Medical University of South Carolina. It points out that the loosely defined condition has symptoms including weakness, slowness, easy exhaustion, low endurance and weight loss.
Researchers at Brigham and Women's Hospital were particularly enthusiastic about the strong association between yoga and walking speed, which has a "well-established connection" with survival, Loewenthal said. "Slower walking may indicate that the vicious cycle of frailty is developing, which is associated with earlier death," she said.
While standards have not been established for optimal "yoga dosage," the authors note that previous studies have recommended two to three one-hour sessions per week.
The Brigham researchers caution that the review has limitations. The studies they looked at used different yoga styles, though most were based on Hatha, and the length of the yoga interventions ranged from 4 to 28 weeks. Many studies also had small sample sizes.
Yoga also did not appear to improve handgrip, another metric associated with frailty, and there was less evidence it improved balance, possibly because many of the studies used chair-based methods. The practice is also not necessarily more beneficial than other forms of exercise, such as tai chi, the authors note.
"All of these practices work across multiple body systems, which is why they are likely helpful for frailty, and they are all healthy choices," Loewenthal wrote, adding that more research is needed to compare different forms of exercise and their effects on frailty.
Christian Osadnik, a professor of physiotherapy at Australia's Monash University who studies frailty, said it was "difficult to draw any firm conclusions" from the Brigham research. He added that the review "didn't, unfortunately, have any strong outcome evidence that actually says even that yoga does help, prevent, or reverse frailty."
Still, he says the review offers a pathway to further research and might counter negative stigma around frailty. "[Some people think that] if someone has frailty, they're in the 'too hard' basket, and we can't do much to help them," Osadnik said. "This kind of information helps us to perhaps appreciate that we can do something."