In a complex sequential movement, what component of the motor program is improved with intensive practice, sequence timing or ensemble motor learning?

We investigated whether the higher maximum speed of complex athletic movements attained by experts compared with novices might solely be ascribed to the acquisition of a more efficient timing of the initiation of the simple movements that comprise complex sporting gestures. Six novices in fencing and five experts in fencing performed three experimental series: 7 trials of touche, 7 trials of lunge (control series) and 50 trials of lunge + touche (test series), where the touche and lunge were initiated with different chronological sequences imposed by the experimenter. The lunge and the touche can be assimilated to a fast forward step and to a pointing task, respectively. We compared the maximum speed of touche between the two groups, recorded by an accelerometer fixed to the hand guard of the foil, and the speed of the centre of mass obtained from a force plate. The speed of the centre of mass was not statistically different between the two groups in the control and in the test series. The maximum speed of touche was not statistically different between the two groups in the control series. In contrast, in the test series, the maximum speed of touche was higher in the fencers' than in novices' groups, while the timing of initiation of the lunge and the touche was similar. The results of the test series show that the higher maximum speed of touche of fencers compared with novices cannot solely be ascribed to the acquisition of a more efficient initiation timing in motor programming. In a complex fencing gesture, the higher maximum speed of touche following intensive practice is discussed with regard to the inhibition of negative effects linked to the "refractory period" associated with the initiation of two closely spaced motor programs.