Kendra Sickinger

Objectives  Anatomy orientation  Surfaces  Coefficient of friction  Impulse  Prevention

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

Anatomy Orientation

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:// turf-sports-injury-prevention.asp  Goal-Tek Innovations ltd. Soccer Safety E- Book. Turf Field Hazards (5). tek.com/SoccerSafety_ch05.asphttp://  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).