Shaw, 30, revealed his diagnosis in a video posted Tuesday to the Titans website.
“I'm here today to stand up and fight with all of you against this disease,” he said before dumping a Gatorade bucket full of ice water over his head. He then challenged the Titans organization, the Penn State football team and coach James Franklin, and his community in Clarenceville, Michigan, to follow suit.
ALS is considered a rare disease, affecting an estimated two in every 100,000 Americans each year, according to the ALS Association. But some studies suggest football players have a higher risk, with one 2012 report finding NFLers were four times more likely to die from the disease. Some evidence points to a higher risk among soccer players, too.
“It remains unclear whether exercise is indeed a risk factor and what types of exercise may be of concern,” the ALS Association’s website reads, noting that “pesticides or some other chemical encountered on maintained playing fields” might also be involved. Chronic traumatic encephalopathy or CTE -- a neurodegenerative disorder linked to concussions -- also shares symptoms with ALS.
Pete Frates, the 29-year-old behind the ice bucket challenge, played baseball, like Lou Gehrig himself.
"The concept that this disease could be over-represented among athletes has been in the medical literature for a long time, and no one underscores that concept more than Lou Gehrig," Dr. Robert Brown, chair of the Department of Neurology at the University of Massachusetts Medical School in Worcester and president of the ALS Therapy Alliance said in a 2012 story about Frates’ diagnosis. "But the interesting question is: Does athleticism set the stage for motor neuron degeneration, or does that same property that makes a person a great athlete also make them susceptible to the disease?"
Most people with ALS are diagnosed between the ages of 40 and 70, according to the ALS Association, and only 25 percent of them are alive five years later.
Brown said the “sense of tragedy looms even larger” for people diagnosed in their 20s and 30s, like Frates and Shaw.
"The irony is that at a time when their muscles are wasting away, we see extraordinary courage and motivation, and what can only be called strength,” he said.