Due to the brutal nature of American football, collegiate athletes run the risk of sustaining head injuries over the course of playing the game. High-speed collisions involving blows to the head are especially dangerous.
Suppose the president of the National Collegiate Athletic Association (NCAA) imposes a new rule that requires college football players at all levels to wear a soft, protective covering over their helmet, designed to reduce the impact of hits to the head that occur when playing the sport.
While the new protective coverings worn over helmets (increase or decrease) the probability of injury resulting from blows to the head, the additional safety measures could also incentivize football players to play more (carefully or recklessly) , which could potentially (decrease or increase) the amount of high-speed collisions and thus the number head injuries suffered by college players, all else equal.