There are several factors that may put an athlete more at risk for certain injuries than others. Intrinsic or personal factors that could put an athlete at higher risk for injury could be gender. For example, female athletes are typically more prone to injuries such as ACL tears. There are approximately 1.6-fold greater rate of ACL tears per athletic exposure in high school female athletes than males of the same age range. Other intrinsic factors are age, weight/body composition, and height, lack of flexibility or range of motion, coordination, balance, and endurance. In addition, biological factors such as pes planus, pes cavus, and valgus or varus knees that can cause an athlete to have improper biomechanics and become predisposed to injury. There are also psychological factors that are included in intrinsic risk factors. Some psychological factors that could make certain individuals more subject to injury include personal stressors in their home, school, or social life. There are also extrinsic risk factors that can effect an athlete's risk of injury. Some examples of extrinsic factors would be sport specific protective equipment such as helmet, shoulder pads, mouth guards and shin guards, and whether or not these pieces of equipment are fitted correctly to the individual athlete to ensure that they are each preventing injury as well as possible. Other extrinsic factors are the conditions of the sport setting, such as rain, snow, and maintenance of the floor/field of playing surface.