parkinsons disease and segmental coordination during turning i standing turns objective many of the falls among people with parkinsons disease pd occur during sudden onthespot turning which requires systematic reorientation of axial segments towards the new direction we examined whether a disturbance in the coordination of segmental reorientation is an important cause of turning difficulty in individuals with pd and is altered by dopaminergic medicationmethods the sequence and timing of segmental reorientation during 45 and 90 onthespot turns was examined in fourteen individuals with pd while off and on medication and nineteen healthy controls hcresults regardless of the magnitude of the turn hc reoriented their head shoulder and pelvis simultaneously followed by mediolateral foot displacement pd patients displayed temporal coordination patterns similar to the hc pd however reduced the velocity and early magnitude of reorientation of each body segment which were both slightly improved by dopaminergic medicationconclusion our finding that the hc and pd patients turn en bloc when the turn is predictable and there are no time constraints shows that the strategy of en bloc turning is not wrong if the movement parameters are unconstrained however in real life situations which usually require quick and unpredictable turns the en bloc strategy may be unsafe and more likely to result in falls while in such situations hc are able to change the strategy from en bloc to sequential segmental turning pd patients may not be able to do so and continue to turn en bloc