Defining movement instabilities in yips golfers using motion capture and muscle synergies.

9Yips9 is an involuntary movement disorder seen in some professional golfers. The diagnostic challenge in yips is to distinguish symptoms of task-specific dystonia from psychological 9choking9. We evaluated 15 professional golfers with mild symptomatic yips via anxiety tests, motion-capture and surface electromyography during a 9putting9 task. Movement instabilities were analyzed via temporal statistical methodologies (one-dimensional statistical parametric mapping). In a subset of golfers, we found significant differences in angular velocities of the putter-club rotation and altered synergy neural coefficients during the downswing phase. Our results showed that golfers with mild yips require sensitive motion-capture evaluations wherein movement instabilities become evident. Particularly the downswing is affected, and the ensuing perturbations in phasic muscle activity share dystonic features that are consistently identified as abnormal muscle synergy patterns. Despite a strong subjective feeling of yips that golfers complain of, movement analysis can reliably exclude those with 9choking9 from those with task-specific dystonias.