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Aim: The purpose of the present study was to evaluate the associations between body composition and functional movement patterns in athletes of different sports. Methods: A cross-sectional study was conducted on 85 voluntary athletes (age 25.9 ± 5 years), representatives of 5 professional Italian teams: 30 volleyball players, 25 soccer players and 30 rugby players. Whole-body impedance measurements and Bioelectric Impedance Vectorial Analysis (BIVA) were performed in order to assess body composition in the athletes. Functional Movement Screen (FMS) was used to assess the presence of dysfunctional and asymmetrical movements. For a more detailed analysis, FMS was separated into three parts: FMSmove, FMSflex and FMSstability. Results: Total FMS score was significantly negatively correlated with percentage of fat mass (%F) and body mass index (BMI). A one-way analysis of variance showed significant differences in body composition and functional movement patterns measures in the three groups. A Tukey post hoc analysis revealed that rugby players have higher %F and body cellular mass (BCM) values than the other groups; moreover, they showed lower scores in FMSflex. The highest scores in FMSflex were obtained by the volleyball players. Conclusions: The main finding of this study was the significant association between higher %F and BMI with poorer functional movement in athletes. Furthermore, with respect to the sport played, rugby players showed significant differences in body composition and movement patterns compared to soccer and volleyball players. In general, reaching an optimal body composition is essential to improving the quality of movement, in order to achieve high performance. However, a large body mass in rugby players could be advantageous in some phases of the match. Reference 1. Fuller JT, Chalmers S, Debenedictis TA et al. (2017) High prevalence of dysfunctional, asymmetrical, and painful movement in elite junior Australian Football players assessed using the Functional Movement Screen. J Sci Med Sport. 20:134–138.

Aim: Investigation of the combined occurrence and characteristics of saccades and microsaccades during free-viewing sport task, with the intention to explore gaze behaviour that would optimize information gathering for action outcome prediction. Methods: Gaze behaviour of expert and novice table tennis players was recorder during a task in which subjects were instructed to predict the ball future direction after the opponent’s throw. Response accuracy, reaction time, fixations, microsaccades and saccades were recorded to estimate the relationship between gazing strategy and success in the task. Analysis of the sequence of saccades/fixations and microsaccade dynamics (during fixations) allowed to study allocation of overt or covert attention in successful predictions. Results: Compared to novices, experts showed more correct responses (70% vs. 64%) with shorter reaction time (411.88±94.62 vs. 468.56±123.22 ms). Experts fixated more times and for longer periods, with more saccades and microsaccades, on hand-racket during forehand and on trunk during backhand drive technique. Furthermore, experts showed a narrower frequency distribution of microsaccade orientations when fixating on hand-racket and trunk areas, meaning that the attention was focused on those small locations. Conclusions: Microsaccades and saccades can be related to the salience of interest areas during performance. Athletes who play ball games are repeatedly exposed to motion stimuli during their training, improving their perception of moving objects. The link between visuomotor performance and covert attention shifts could have a potential impact upon sports, as for example assessments of visual performance that can help to predict people who have elite potential. On these premises, one can suggest that vision training offers a mean to improve performance. References: 1. Piras A, Raffi M, Lanzoni IM, Persiani M, & Squatrito S. (2015) Microsaccades and prediction of a motor act outcome in a dynamic sport situation. Invest Ophthalmol Vis Sci Title, 56(8), 4520–4530. 2. Piras A, Lanzoni IM, Raffi M, Persiani M, & Squatrito S. (2016). The within-task criterion to determine successful and unsuccessful table tennis players. Int J Sports Sci Coach, 11(4).

Aim: The self-motion perception produced by optic flow fields is part of the sensorimotor integration process finalized to the postural control. Depending on the stimulated portion of the retina, the corticocortical signals are differently processed. The aim was to investigate if retinal impairments modify the activity of postural muscles. Methods: We evaluated the electromyographic (EMG) activity of the tibialis anterior and soleus in 34 volunteers. Thirteen people at early stage of retinopathy were included in the ‘‘retinopathy group’’ (average age 62), eight people with a laser treatment on the peripheral retina were included in the ‘‘laser group’’ (average age 62) and thirteen healthy subjects formed the ‘‘control group’’ (average age 59). The EMG activity was recorded while the subjects viewed radial optic flow stimuli presented in the foveal, peripheral and full visual field. A repeated measures ANOVA was performed on the normalized EMG of each muscle, with side (right–left) as within-factor and group and stimuli as between-factors. Results: The EMG analysis of the tibialis showed a significant effect for group (p = 0.012) and an interaction effect side by group (p = 0.06). The EMG analysis of the soleus showed a significant effect for group (p\0.001) and an interaction effect side by group (p\0.001). Further, the retinopathy group showed the highest values of muscles activation, while the laser group presented the lowest. The retinopathy and the laser groups activated predominantly muscles of the same side, left and right respectively. The control group activated left tibialis and right soleus. Conclusion: Results showed that the retinal functionality influences the activity of postural leg muscles. We hypothesize that in presence of retinal damage the postural control system may induce a co-contraction of leg muscles in order to maintain stability. Results seem to indicate that an impairment of the peripheral retina reduces the muscles activity. References 1. Peterka, R. J. (2002). Sensorimotor integration in human postural control. Journal of neurophysiology, 88(3), 1097–1118 2. Raffi, M., Piras, A., Persiani, M., & Squatrito, S. (2014). Importance of optic flow for postural stability of male and female young adults. European journal of applied physiology, 114(1), 71–83. 3. Raffi, M., & Siegel, R. M. (2004). Multiple cortical representations of optic flow processing. In Optic flow and beyond (pp. 3–22). Springer Netherlands.

Optic flow is crucial for the maintenance of quiet stance in the upright position. However, little is known about the correlation between stimulus type and postural response. Aim of this study was to investigate the optic flow effect on the distribution of the prevalent direction of postural sway. Stabilometric data were recorded in 24 right-handed young volunteers who stood with each foot on a Kirstel force platform, facing a wide screen. Optic flow stimuli were full screen expansion and contraction, while random dot motion was used as control. For each stimulus we computed the maximum variance of sway direction (the prevalent oscillation direction) and the mean vector. The vector of the prevalent direction of postural sway was 127.7° in expansion, 223.7° in contraction and 211.4° for random stimulus. All stimuli showed a uniform distribution at the Rayleigh test, but we did not find a correlation between the stimuli, meaning that each stimulus evokes a proper postural sway. Contrary to males, females showed a prevalent forward sway during contraction. A possible explanation for this might be that a different muscular activation could cause a different posture during the stimulus presentation. It is possible that the activation of either plantaflexors or plantaextensors during the trial caused a continuous oscillation in anteroposterior direction. That would require the generation of a stronger vertical force to keep postural stability and to avoid backward fall.

While retinal optic flow (OF) is considered a major cue for self-motion and postural stability, it is still debated the relative importance of central vs peripheral vision in visuo-postural responses. Psychophysical studies, by assessing the body sway in response to OF stimuli give more importance to visual periphery as source of compensatory postural responses, while the central vision would play an accessory role. Aim of this study was to verify the different influence of central vs peripheral optic flow stimulation on the activation of lower limb postural muscles: bilateral tibialis anterior and gastrocnemius medialis. Surface EMG was recorded in 24 male and female participants while radial (expansion and contraction) OF stimuli were presented either in a central or peripheral region of a wide screen. The activity of the right tibialis anterior was the most affected by OF stimuli. We found an interaction of sex by muscle in favour of male subjects (78%). The majority of the subjects had a greater postural response for either central or peripheral stimulation, meaning that the influence of visual field region on visuo-postural balance may be subject-specific, probably depending on other stimulus parameters

Introduction Several researches have been aimed at studying the balance control looking at the variation of the center of pressure (COP) trajectory induced by variation of the visual field (Collins & De Luca, 1995; Accornero, 1997). Indeed, presence of a visual stimulus produce less sway speed than the dark (Lee & Lishman, 1975). However, little is known about the modulation of optic flow stimuli on the body sway. Aim of this study was to verify how the direction of optic flow can affect the COP parameters like speed, trace length, equivalent area and equivalent radius. Methods Stabilometric data were recorded in 24 healthy right-handed volunteers (12 M and 12 F, mean age 24.5±2.9) who standed on two Kirstel force platforms. Experiments were performed in the dark. Stimuli were presented on a wide screen, placed 115 cm from the subjects’ eyes, covering 135 x 107° of visual field. Stimuli were two full screen optic flow, expansion and contraction, and random dots motion as control stimulus. Postural responses data were acquired by the SMART BTS® at 1000 Hz (BTS® Bioengineering Inc.). Data acquisition included 5 trials per stimulus for about 30-s each. Results We performed a repeated measure ANOVA on the 24 subjects for each COP parameter. Speed: we found significant differences across the optic flow stimuli (p=0.042) and significant interaction between stimulus and sex (p=0.009). Trace length: results showed significant interaction between stimulus and sex (p=0.001). Equivalent area: we found significant interaction between stimulus and sex (p

A feedback control based on the visual perception self-motion contributes to postural stability, however little is known about the visual modulation of postural muscles. Aim of this study was to investigate the effect of optic flow direction on the muscle activation and to verify the correlation between visual stimuli, muscle activity and body sway. We used surface electromyography (EMG) and stabilometry on 24 right-handed young adults. Center of pressure (COP) and EMG data were acquired at once. We analyzed the bilateral activation of tibialis anterior and gastrocnemius medialis during full field expansion or contraction optic flow stimulation. A stimulus made of dots moving in random directions was used as control. The activity of the tibialis anterior and gastrocnemius medialis resulted well correlated to the antero-posterior COP displacement. We analyzed the highest EMG amplitude values to evaluate if optic flow differently modulated the muscle responses. The stimulus effect was significant in 23 subjects (96%). In the tibialis anterior we found a laterality effect in males (p