A recent research concluded that restricting participation of patients with single kidney from contact sports is totally unwarranted.
It has been a practice of most physicians to recommend that children with single kidney should not participate in football. This was proven by the survey of 436 members of the American Society of Nephrology wherein 62% of them stated that they would not allow contact sports for these patients and 86%, particularly in American football. What is notable about the survey is that only 5% barred cycling.
The irony is that cycling is the most common cause of sports related injury. And this is three times greater than football.