The Science of Yoga

human body. It lets the arm achieve an astonishing range of motion—up, down, sideways, rotated—through a clever but risky stratagem that centers on a shallow ball-and-socket joint. The rounded head of the humerus, the main arm bone, rests in a very modest socket on the scapula, or shoulder blade, which children like to call angel wings. The shallowness of the socket gives the humerus wide freedom of movement but also raises the risk of the ball popping out. The job of holding it in place goes mainly to the rotator cuff. Its four or five muscles (the number depends on the authority) originate on the scapula and fasten to the head of the humerus through the tough cords known as tendons. Atop the humeral head, the tendons merge to form a taut cap of connective tissue that not only holds the shoulder tightly in place but also, in something of a contradiction, helps move the arm.
    Tears of the rotator cuff usually involve the tendons, limit arm motion, and can be quite painful. Athletes who raise their arms in repetitive patterns—swimmers, tennisplayers, baseball pitchers—know the problem well. The tears most often occur in the tendon of a muscle known as the supraspinatus, which lies above the rotator group. Its name derives from its origin just above a bony spine that runs across the scapula.
    Fishman said he tore his right rotator cuff while skiing. He had surgery on it and then, a few years later, tore his left rotator cuff as well. His surgeon judged the tear quite serious and suggested he get an appointment with the city’s best specialists. It was a total supraspinatus tear, and Fishman experienced the usual pain and arm limitations. Without assistance, he could raise his arm no higher than eighty degrees—a bit less than perpendicular to his body.
    One day at home, during the month-long wait for a surgical consultation (yes, even physicians get caught in that kind of delay), Fishman was doing yoga and decided to attempt a Headstand. He found he could do it. Getting his head down and arms into the right position was no problem.
    “My wife said, ‘What are you doing? ’ ” he recalled. “I got up to tell her and found I could raise my arm. Before, I couldn’t. I went to the office and did it again. It kept working.”
    Astonished, Fishman threw himself into a program of research and confirmation, including visits with top surgeons. Both said he no longer needed surgery and expressed bewilderment at how little science understood the mechanics of the arm.
    At his own office, Fishman led an investigation into how the Headstand had achieved the cure. His main tool was the electromyograph—the heir to Jacobson’s methods for tracking muscle activity. It let Fishman and his aides zero in on rotator activation. The team took measurements as he stood upright and on his head. The readings showed that two other rotator muscles had joined the action—the subscapularis and the rhomboid major. They engaged most when Fishman inverted his posture and proceeded to raise his shoulders—a key feature of the Iyengar Headstand. Iyengar taught that, once students were upside down, they should widen and raise their shoulders as far from the floor as possible. That extra lift turned out to be the main factor that produced the healing benefits.
    Fishman concluded that the Headstand taught the other rotators to assume new roles. “It’s training yourself to use a different muscle,” he said, smiling, talking amile a minute. By another name, it was muscle substitution—avoiding an existing problem by using other muscles.
    Pleased with the results, Fishman decided to see if the benefits could extend to others. He asked the next patients with torn rotator cuffs if they would like to try the Headstand cure. Sure, ten answered. He and his assistants taught them an easy form of the inversion that they could do with the help of a folding chair.
    Fishman’s prescription? Do it once a day for thirty seconds. Nothing more. At the end of six weeks, he and his team checked the patients. To Fishman’s delight, nine of the ten found they could move their arms like a person with a healthy shoulder. All decided to forgo surgery.
    Sharon Williams, a development director at Dance Theater of Harlem, had come to Fishman with chronic pain in her right shoulder. It had ached for a month, and examination revealed a partly torn rotator cuff. After she started the Headstands, the pain went away and she found that her arm could once again