Nearly 40 percent of NFL players last season wore a helmet model that got the second-lowest rating for reducing the risk of concussions in a study by Virginia Tech researchers. Riddell's VSR-4 helmet received just one star in a study of football helmets led by Virginia Tech professor of biomedical engineering Stefan Duma and released Tuesday. Another Riddell model -- the Revolution Speed -- was the only helmet that earned five stars, the top rating. Five models -- two made by Riddell, two by Schutt and one by Xenith -- received four stars. According to Riddell, 38 percent of NFL players wore the low-rated VSR-4 in 2010. The company also said 39 percent wore one of the various models that fall under the Riddell Revolution name or the new Riddell 360. Read more: http://sports.espn.go.com/nfl/news/story?id=6517927
