American football is a dangerous sport and is characterized by violent contact between people that often leads to repetitive head injury. A multitude of health effects may result from this sort of head injury, but a new finding reported in the December issue of JAMA Neurology maintains that football players are at risk for developing low testosterone levels and erectile dysfunction. Rachel Grashow, PhD, from Harvard T.H. Chan School of Public Health and the Football Players Health Study at Harvard Medical School discusses the findings regarding the relationship between head injury and erectile dysfunction.