it shows us that every single player who s played the game at some point is thinking and wondering and worried about it. it is something it is pervasive. reporter: at the university of alabama birmingham, an effort to update helmet tests that haven t changed since 1969. tracking not only the head-on force but the twisting torque and rotation that causes even more damage to the player. hits that have all nfl players from quarterback to linebacker concerned for their health. jim avila, abc news, new york. and last night dan marino explained his decision saying within the last year i authorized a claim to be filed on my behalf in the event that i later suffered the effects of head trauma. in doing so, i didn t realize i would be listed as a plaintiff in the lawsuit against the nfl. marino went on to say he is sympathetic to other players who suffered head injuries but he is withdrawing as a plaintiff. the most highest profile plaintiff in the suit. very high profile.
it shows us that every single player who s played the game at some point is thinking and wondering and worried about it. it is something it is pervasive. reporter: at the university of alabama birmingham, an effort to update helmet tests that haven t changed since 1969. tracking not only the head-on force but the twisting torque and rotation that causes even more damage to the player. hits that have all nfl players from quarterback to linebacker concerned for their health. jim avila, abc news, new york. and last night dan marino explained his decision saying within the last year i authorized a claim to be filed on my behalf in the event that i later suffered the effects of head trauma. in doing so, i didn t realize i would be listed as a plaintiff in the lawsuit against the nfl. marino went on to say he is sympathetic to other players who suffered head injuries but he is withdrawing as a plaintiff. the most highest profile plaintiff in the suit. very high profile.