Kimberley Luu and associate professor Peter Hall, of the School of Public Health and Health Systems at the University of Waterloo in Ontario, Canada, report their study in the journal Mindfulness.
Yoga and meditation, once regarded as predominantly Eastern customs, are becoming mainstream in the West.
The U.S. workforce is rapidly taking to yoga and meditation. A recent study from the Centers for Disease Control and Prevention (CDC) found that yoga practice among workers in the U.S. more than doubled between 2002 and 2012, rising from 6 to 11 percent. Meditation practice also rose from 8 to 9.9 percent.
Hatha yoga and mindfulness
Of the many styles of yoga, the one most commonly practiced in the West is Hatha yoga, which combines breathing with meditation and movement and concludes with relaxation. Ashtanga and Iyengar yoga are examples of Hatha yoga.
Mindfulness meditation is an approach that emphasizes paying attention to what is going on in the mind without evaluating or judging it. While yoga often includes some aspects of mindfulness, it can also be practiced on its own.
Prof. Hall explains, “Hatha yoga and mindfulness meditation both focus the brain’s conscious processing power on a limited number of targets like breathing and posing, and also reduce processing of nonessential information.”
He explains that he and Luu were interested in finding out whether the two practices might have a “positive carryover effect” that helps people to “focus more easily on what they choose to attend to in everyday life.”
In a comprehensive review of the evidence, the two authors had already concluded that there was a need for “more good-quality studies” on the effects of Hatha yoga on executive function.
In that paper, they describe the executive function as “a set of high-order cognitive processes” that allows control of behavior, emotion, and thought independently of stimuli.
The executive function operates through the prefrontal cortex of the brain and other centers that are linked to it. It typically involves working memory, mental flexibility, and inhibitory control.
Many researchers also regard executive function as inclusive of other processes such as decision-making, problem-solving, and attention control because they are closely linked to it or highly dependent on it.
For their new study, the researchers invited 31 healthy, “moderately experienced” practitioners aged 28 years, on average, to complete three sessions of Hatha yoga (including an element of mindfulness meditation), mindfulness meditation (without yoga), and quiet reading (control task).
They used a “within-subjects experimental design,” which meant that the participants did not complete the tasks in the same order (each was assigned the order at random).
Improved executive function, mood, energy
The researchers assessed executive function before each session and at 5 minutes and 10 minutes after each session using a standard test known as the “Stroop interference task.” This test also measures inhibitory control.
The team found that the participants significantly improved their executive function scores after the Hatha yoga and mindfulness meditation sessions compared with the before and after scores of the reading session.
However, they note that the improvement only showed in the 10-minute post-session tests and not in the 5-minute post-session tests.
Using a self-reporting tool called Profile of Mood States, the researchers also found that both Hatha yoga and mindfulness meditation resulted in significantly improved mood scores compared with reading.
This tool includes a “vigor-activity subscale” that measures energy levels. On this subscale, while both Hatha yoga and mindfulness meditation compared favorably with reading, Hatha yoga showed “significantly greater benefits.”
Luu explains that there are “a number of theories about why physical exercises like yoga improve energy levels and cognitive test performance. These include the release of endorphins, increased blood flow to the brain, and reduced focus on ruminative thoughts. Though ultimately, it is still an open question.”
Because the participants were not representative of the general population, more studies are now needed, involving diverse groups of people, to find out whether Hatha yoga and mindfulness meditation might benefit the wider public.
“Although the meditative aspect might be even more important than the physical posing for improving executive functions, there are additional benefits to Hatha yoga including improvements in flexibility and strength. These benefits may make Hatha yoga superior to meditation alone, in terms of overall health benefits.”