Legendary boxer Muhammad Ali passed away this summer after living for more than 30 years with Parkinson’s disease. It’s a neurological disorder that affects the way the brain communicates with the body. Some speculate repeated head trauma contributed to Ali’s illness. But except for the contact side of the sport, boxing may slow the progression of the disease. That idea is the foundation of a study led by Northern Arizona University testing the benefits of boxing on people with Parkinson’s.