Alireza Aminaee - PhD Student of Motor Control, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran
Shahzad Tahmasebi Boroujeni - Associate Professor of Motor Behaviour, Department of Motor Behaviour and Sport Psychology, University of Tehran, Tehran, Iran
Elahe Arab Ameri - Associate Professor of Motor Behaviour, Department of Motor Behaviour and Sport Psychology, University of Tehran, Tehran, Iran
Mehdi Shahbazi - Associate Professor of Motor Behaviour, Department of Motor Behaviour and Sport Psychology, University of Tehran, Tehran, Iran
Ali Sharifnezhad - Associate Professor of Sport Biomechanics, Department of Sport Biomechanics and Technology, Sport Science Research Institute, Tehran, Iran

Highlights: Expert Table Tennis players demonstrate higher APA magnitude of dorsal muscles than novice counterparts. Expert and Novice Table Tennis players show similar APA onset time. Skilled Table Tennis players have ability to anticipate body position change more effectively than novice player. The greater the available time for motor preparation, the better anticipation of the APAs Abstract Background: Skilled athletes’ optimal performance might be due to their postural ability to counteract perturbation. However, how expertise influences coordination of anticipatory postural adjustment (APA) and main movement under temporal pressure needs more investigation. This study aimed to investigate how available time (temporal pressure) for central nervous system to prepare postural and motor commands, differentiates skilled and novice postural capacity during performing Table Tennis Forehand stroke. Methods: ۱۰ skilled (۲۰.۳±۱.۱۵ years old) and ۱۰ novice (۱۹.۹±۰.۹۹ years old) Table Tennis players while maintaining Forehand stroke position on two force plates, stand in front of a screen that presenting Coincident Anticipation Timing stimulus. Participants completed a block of ۲۰ trials consisted of random-order presentation of fast and slow stimuli and surface muscle activity of postural muscles were recorded using Electromyography device, simultaneously. Results: The results of two-way MANOVA showed that, more/less temporal pressure for central nervous system led to later/earlier onset time of APA with lower/higher magnitude, respectively. Skilled players’ postural strategy was higher magnitude of APA in dorsal muscles (Erector Spainae, Biceps Femoris and Gasterocnemous), more backward peak excursion and lower velocity of centre of pressure. Conclusion: Although such findings may be beneficial factors for coaches in programming athletes’ training, however, the similarity in anticipatory postural adjustments’ onset time of novice and skilled players, do not let certain conclusion about the effects of expertise on feed-forward control of posture.

Electromyography, Coincidence Anticipation, Anticipatory Postural Control, Table Tennis, Muscle Activation