American football American football American football, referred to as football in the United States and Canada and also known as gridiron, is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, which is the team controlling the oval-shaped football, attempts to advance down the field by running with or passing the ball, while the defense, which is the team without control of the ball, aims to stop the offense's advance and aims to take control of the ball for themselves. The offense must advance at least ten yards in four
Health issues in American football to field condition. Because American football is a full-contact sport, head injuries are relatively common. According to the San Francisco Spine Institute at Seton Medical Center in Daly City, California, up to 1.5 million young men participate in football annually, and there are an estimated 1.2 million football-related injuries per year. An estimated 51% of injuries occur during training sessions, while 49% occur elsewhere. Injuries are nearly 5 times more likely to happen during contact training sessions than in controlled, non-contact sessions. Older players are at the most risk for injuries, while teams with experienced coaches and more assistant coaches