Legendary running back Earl Campbell, of University of Texas and Houston Oilers fame, is suffering from debilitating ailments that have left doctors looking for answers. Tests have come up negative for Lou Gehrig’s disease, but his physicians are initiating nerve treatments in hopes that a solution can be found.

According to the AP, the NFL Hall of Famer and Heisman Trophy winner “compares the effects of the nerve problem to a robot that moves its right leg when instructed to move its left.”

Campbell will be hospitalized in Houston. His aggressive style of play also took a toll on his knee, and since undergoing surgery last year has had to make use of a walker to aid his mobility.