Associations of Masticatory Muscles Asymmetry and Oral Health with Postural Control and Leg Injuries of Elite Junior Soccer Players.

The influence of asymmetry between masticatory muscles on postural control is still under debate and only few studies examined the impact of oral health on injury risk. The present study investigated the relationships between masticatory muscles asymmetry, oral health, postural control and the prevalence of (non-contact or traumatic) leg injuries in a sample of 144 male elite junior soccer players. sEMG of the masseter and temporal muscles was performed during maximum teeth clenching, postural control was tested by measuring sway velocity during the unipedal stance with eyes closed, while oral health and the number of leg injuries were assessed using a questionnaire. The time-1 assessment was repeated in a subgroup of 69 players after one year. Pearson and partial correlation coefficients and adjusted odds ratios (OR) were used to assess associations. Asymmetry between the masseter and temporalis muscles (AMTM, quantified as anteroposterior coefficient, APC) was associated with higher sway velocity on the dominant leg (using time-1 data partial r = -0.24, p = 0.004, using longitudinal data partial r = -0.40, p = 0.005). Higher prevalence of two or more leg injuries throughout a competitive season was associated with poor oral health (adjusted OR (95%CI) using time-1 data = 2.14 (1.02-4.46), using longitudinal data = 4.47 (1.25-15.96)). These results indicate that AMTM has a negative influence on the sway velocity of the dominant leg only, possibly because frequent balancing exercises on the non-dominant leg may counteract negative influences of AMTM. The association of oral health with leg injuries underlines the need for oral health promotion and monitoring strategies in sports.