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

‘Yips’ 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 ‘choking’. We hypothesized that in mild-yips golfers, the yips-like shots demonstrate features that are distinguishable from normal-shots allowing for an objective classification. 15 professional golfers with subjective complaints of yips were assessed via motion-capture and surface electromyography during a ‘putting’ task. Normal-hits and yips-shots were identified by golfers’ subjective responses over the trials. Angular velocities of putter club and muscle synergies were analyzed during the swing phase using 1-dimension statistical parametric mapping. Participants had long golfing careers with considerable duration of yips symptoms. While task-based video evidence was inconsequential, in a subset of golfers, we found significant differences in angular velocities of the putter club and altered synergy neural coefficients during the downswing phase. Our findings showed that golfers with mild-yips require precise motion-capture to define movement instabilities which may not be evident with simple videography. 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. Dystonia in mild-yips therefore obligates sensitive multimodal assessment to differentiate from golfers with ‘choking’.