The National Football League (NFL) has taken a new interest in the safety of its players.

In September, several new rules will go into effect, among them a rule aimed at reducing concussions.

The rule will impose a 15-yard penalty for delivery of a blow with the crown of the helmet. If the offensive and defensive player each lower their heads and uses the crown of the helmet to make contact, each will be penalized.

New magnetic resonance imaging techniques have shown that the effects of concussions are more serious than previously thought, demonstrating global atrophy one year after just a single concussion, according to a paper published online ahead of print in Radiology by Yongxia Zhou, PhD, and colleagues.