"For the first time, several key rotational-biomechanic elements of the golf stroke in its entirety, from backswing to follow-through, were analyzed, and then the data were used to generate benchmark curves, said Jessica Rose, PhD, associate professor of orthopaedic surgery and senior author of the study."The medical object of the study was of course to study golf-induced injuries by studying swing fundamentals. It was found that pros do in fact swing differently than amateurs:
"Researchers analyzed several biomechanical elements of subjects’ golf swings, including S-factor (tilt of the shoulders), O-factor (tilt of the hips) and X-factor — the relative rotation of the hips to the shoulders, measured in degrees — which is considered key to power generation. Previous research has shown that pro golfers who hit the ball far generally have a larger peak X-factor than their peers, but this study is more extensive in that it considers X-factor in relation to other rotational biomechanics of the golf swing over the full duration of the motion."Of immense use to all golfers, pro or amateur, and immensely valuable to teaching professionals, the study found for the first time scientifically that it is hip rotation that initiates the downswing:
"Conrad Ray, the Knowles Family Director of Men’s Golf at Stanford University and a co-author of the study, said the findings give scientific backing to the elements of golf-swing form that professionals have long understood are vital for generating power. The study also helps to clarify some unresolved questions about golf-swing biomechanics, Ray said. “One question that always comes from students is, ‘What starts the downswing?’” he said. “People have had different answers. Some would say the hands, or others would say the shoulders or the lower body. But the study confirms that rotation of the hips initiates the downswing. So that, to me, is an interesting finding.”"