Yoga studies
One of the first studies that caught my eye was conducted by the folks at the American Council on Exercise in San Diego. Working with researchers from the University of Wisconsin, La Crosse, the ACE experts set out to determine what effect regular yoga would have on 34 healthy (but sedentary) women with an average age of 33.

The women were divided into two groups: a yoga group and a non-yoga control group. All the women were evaluated for flexibility, muscular strength and endurance, balance, pulmonary function, and fitness level. The non-yoga control group did no exercise for eight weeks, while the yoga group took three 55-minute Hatha yoga classes per week.

Each class started with five minutes of relaxation and yoga breathing (pranayama), followed by 10 minutes of warmup exercises including sun salutations, 35 minutes of yoga postures (asanas), and, finally, five minutes of relaxation and yoga breathing in the corpse pose (savasana), according to an ACE write-up of the study.

Improved flexibility, endurance
At the end of the eight-week study, both groups were evaluated for changes in their fitness levels. The results are not really surprising: the researchers found that on average, the flexibility of the yoga group improved between 13 and 35 percent. The yoga group also built muscular strength and endurance and improved their balance: on average they performed six more push-ups and were able to hold their one-leg poses for 17 seconds longer than the control group.

Yoga may do much more than keep you flexible, however. According to research from the Yale University School of Medicine, people who practice yoga and meditation at least three times a week can reduce their blood pressure and their risk of heart disease. What’s more, the study found improvement with just six weeks of practice. The study’s yoga program included 40 minutes of postural yoga, 20 minutes of deep relaxation, 15 minutes of yoga breathing, and 15 minutes of meditation.

Additional benefits
Other studies have linked yoga to relief of menopausal symptoms, weight loss, and reduction of insomnia, anxiety, and/or depression.

And the studies continue, boosted by an increased interest in the benefits of complementary and alternative medicine. Researchers at Ohio State University (OSU) and the National Center for Complementary and Alternative Medicine (NCCAM) are conducting a clinical trial designed to examine the impact of yoga on immune and hormone function in healthy individuals.

Yoga for cancer patients
Researchers at Wake Forest University and the National Cancer Institute are conducting a clinical trial designed to test whether yoga can improve the symptoms and quality of life and reduce stress in patients with ovarian or breast cancer.

Why investigate yoga? “Everyone thinks yoga has health benefits, but a look at the literature shows we just don’t have good evidence proving these benefits exist,” said Janice Kiecolt-Glaser, PhD, principal investigator on the OSU study. “That’s what this study is about—to see if we can find that evidence.” If the trial results reveal that yoga can reduce levels of stress hormones, then those findings may have implications for reducing the risk of other diseases, OSU researchers note.

If the studies bring more people to the practice of yoga, that’s great. For the rest of us, we’ll just keep doing what we know is good for us.

Barbara C. Bourassa is a freelance writer and editor living in North Andover, Mass.