Here’s the setting: The cavernous Virtue Field House at Middlebury College, 10 a.m. on a quiet Sunday morning early in the fall, the football season. Some 40 to 50 young men, all dressed similarly, shorts and t-shirts with “Middlebury Football” lettering, are arranged in front of a solitary figure who is leading these men, 300-pound linemen as well as 180-pound backs and receivers, through a series of yoga poses and mind-body exercises.