Lou Gehrig, a heroic slugger for the Yankees baseball team, was famed for brushing aside repeated fractures and batting after nearly being knocked unconscious, before giving his name to the disease that was said to have killed him.

But a new study suggests that the player may not have died of Lou Gehrig's disease, formally known as amyotrophic lateral sclerosis (ALS), a type of motor neurone disease. Instead, it may have been the baseballs bouncing off his head that claimed his life in 1941.

According to a paper to be published tomorrow in a leading journal, Gehrig and a string of American football players and soldiers recorded as dying of ALS, may instead have died due to brain traumas.

Research at the Veterans Affairs Medical Centre in Massachusetts and Boston University's medical school have identified markings in the spinal cords of two American football players and a boxer who were said to have died of ALS that suggest they died as the result of a disease caused by concussion or other head trauma that attacks the central nervous system.

The finding, published in the Journal of Neuropathology & Experimental Neurology, now means doctors may have to reassess how to treat athletes suffering lasting effects from concussion, and particularly the rising numbers of American soldiers returning from Iraq and Afghanistan with brain injuries caused by roadside bombs.

Gehrig, who built a heroic reputation for playing on despite injuries - he played 2,130 games over 14 years - is not named in the study. But Dr Ann McKee, the director of the neuropathology laboratory for the New England Veterans Administration Medical Centers, and the lead neuropathologist on the study, said that the implication is that he may well have died not from the disease named after him but from the repeated concussions he received on the baseball field as well as when he played American football in school and at university.

"Here he is, the face of his disease, and he may have had a different disease as a result of his athletic experience," McKee told the New York Times.

The ALS Association in the US says that about 30,000 people have the incurable fatal disease that mostly kills men aged 40 and older by the wasting away their muscles. Among its most prominent victims in the UK is the physicist Stephen Hawking.

• This article was amended on 18 August 2010. Due to an editing change, the original said that Lou Gehrig's disease was formerly known as amyotrophic lateral sclerosis (ALS). The headline said: Lou Gehrig killed by baseball not Lou Gehrig's disease, study finds. This has been corrected.