Giới Thiệu · American Football Wallpapers
If you are American football fan you will undoubtedly be ardent fan of the American football wallpapers. A great number of wallpapers are offered, just take your time and select your favorite one. Throw a pass on your screen but don't forget the helmet. Easy-to-browse interface enables you to find the desired wallpaper in no time. Customize the wallpaper to fit your taste and screen. Zoom, un-zoom, rotate, move, scale, adjust brightness, add various effects and save your background design.American Football NFL is a tough contact sport that dominates the American sporting scene and is gaining popularity in Europe. It is a game requiring all-round physical fitness. Players have to be fast, strong, and proficient in the six basic skills. Some of them are passing and catching. But running and blocking are not less important. American football has always been associated with a large number of injuries, not surprising when the game commonly involves players in excess of 240 pounds colliding with each other at full speed. In the United States, it is estimated that more than 300 000 high school players, 35 000 college players, and half of the National Football League players are injured to some extent each season. Head and neck injuries are common: there are approximately 250 000 incidents of concussion each year. Some injuries have been fatal or have resulted in players becoming permanent quadriplegics. However, the number of very severe injuries has declined in recent years. This is probably due to rule changes concerning tackling and blocking with the head, and improvements in protective equipment which were introduced in 1976. There has also been a greater emphasis in training on strengthening the muscles of the neck and learning good tackling techniques. This is particularly important in the younger age group. Protective clothing is an essential feature of modern game, but this makes the players vulnerable to heat stroke. One study reported 12 heat stroke deaths among college and high school players over a three year period. The victims were all interior linemen, probably the players required to work hardest and longest; most were stricken during pre-season practice so they may have been in poor physical condition; all were dressed in full uniforms which increases workload and interferes with heat loss; and most were not permitted to drink water during practice.
