Once the domain of New Agers and suburban moms, yoga has become firmly planted in Baltimore’s inner city, and now researchers believe the ancient practice may help elementary school students cope with the stress of growing up in impoverished, violent neighborhoods.

Researchers and lay people alike think yoga may help adults reduce stress. The popularity of the practice has surged, and it’s used as therapy for cancer patients and battered women, and as a treatment for back pain and depression.

But even as schools get in on the trend, the effect of the practice on children has …