Effects of soccer boot sole design and prophylactic ankle bracing on knee muscle activity and performance of soccer players

Abstract

Purpose: The major aim of this study was to determine the influence of two different soccer boot sole designs and the use of prophylactic ankle bracing, and their interaction, on the (1) ball flight velocity, (2) passing accuracy, and (3) maximum amplitude of the electromyographic activity in the quadricep and hamstring muscles of the supporting leg of male soccer players performing a side foot pass on artificial turf. Methods: Twenty-five male participants (mean age ± standard deviation = 20.5 ± 2.0 years) were exposed to two boot sole design conditions (i.e., artificial grass boots and natural grass boots) and two ankle bracing conditions (i.e., bracing and no bracing) while performing a side foot pass on artificial turf. The maximum quadriceps and hamstring muscle activity was recorded with surface electromyography and expressed as a percentage of the electromyographic amplitude recorded during a maximal voluntary isometric contraction of the respective muscles; the ball velocity was measured using a sport radar gun; and the number of successful hits of a cone was counted manually. Results: Two-way repeated measures analysis of variance results revealed that natural grass boots increased the quadricep (p = 0.020) and hamstring (p = 0.011) maximum electromyographic amplitude compared with artificial grass boots. No significant difference in the knee muscles maximum electromyographic magnitude was found between the two bracing conditions (p > 0.05). Neither boot sole design nor ankle bracing influenced the soccer performance - ball flight velocity or passing accuracy (p > 0.05). Conclusion(s): Soccer boots designed for natural grass induced higher levels of quadricep and hamstring muscle activity in the supporting leg during a side-foot passing maneuver on artificial turf compared to soccer boots designed for artificial turf, although the actual player performance (passing accuracy and ball velocity) did not differ between the two types of boot sole design. In addition, prophylactic ankle bracing did not affect knee muscle activity or player performance. Implications: Soccer players are advised to use artificial turf boots when playing on artificial turf as they require less knee muscle activity and do not impede player performance. In addition, given its known beneficial effects in preventing ankle sprains, we recommend prophylactic ankle bracing to soccer players and coaches. Key-Words: 1. Soccer shoes 2. Playing surface 3. Ankle brace Funding Acknowledgements: No funding was provided for this study. Ethics Approval: Human Research Ethics Committee of the Institute of Human Performance, the University of Hong Kong.