What is an ankle sprain? Stretching or tearing of ligaments surrounding bone Ankle is in unnatural position, uneven surface, “roll in” Grade I, II, III
Which is more common?
Friction and Forces Friction is the force that opposes efforts to slide or roll one body over another Force needed to plant the foot Surfaces with high coefficients of friction requires large amount of force Higher coefficients leads to more force to more injuries
Coefficient of Friction Rolling friction helps soccer players to determine how the ball will react on turf vs. grass Smaller coefficient, easier for the surfaces to begin rolling or slide Coefficient of 0.0 would indicate a frictionless surface Friction is dependent on the force holding the surfaces together and force needed to slide one surface over Coefficient decreases as f(max) decreases
Why do ankle sprains happen? An unnatural twisting motion Planted awkwardly Ground is uneven Unusual amount of force is applied to the joint Unaware Supporting weight and ankle size
Turf Surface High friction between cleat and playing surface Greater number of injuries due to friction Hardness/sticky feeling In 2000 created synthetic infill artificial surface (eg. FieldTurf, AstroPlay) to create less friction How this ties to impulse F= m(Vf-Vi) T
Different surfaces GrassSand Speed of play is slower (time) Landing on softer surface vs. indoor court Harder to maintainCourt rules Unaware of uneven surfaces time F= m(Vf-Vi) T
Gymnastics Surface Padded surface Fast velocities High impact forces Small margin of error Dorsiflex Overuse
Tied To Class Learned that friction is a force that acts upon opposite direction Too much friction can cause injury Coefficient gets higher, more friction Increasing friction = better performance as well as decreasing friction F= m(Vf-Vi) T Only impact on force is time
Prevention Stability/balance exercises Ankle braces Proper shoe Strengthen muscles around ankle Range of motion
Conclusion Turf vs. grass is still controversial Force and friction Friction surface plays a dominate role in ankle sprains in sports Impulse equation Never 100% prevent F= m(Vf-Vi) T
References Drakos, M. (2008). Artificial Turf: Does it Increase the Risk of Sports Injuries? Hospital for special surgery. turf-sports-injury-prevention.asphttp://www.hss.edu/conditions_artificial- turf-sports-injury-prevention.asp Goal-Tek Innovations ltd. Soccer Safety E- Book. Turf Field Hazards (5). tek.com/SoccerSafety_ch05.asphttp://www.goal- Kinesiology: Scientific Basis of Human Motion. 11th ed. New York: McGraw-Hill, Print. Nicholas Institute of Sports Medicine and Athletic Trauma (2007) Ankle Sprains. Vormittag, K., Calonje, R., & Briner, W. W. (2009) Foot and ankle injuries in the bare sports. American College of Sports Medicine, 8(5).