Olympic shot-putt champion Randy Barnes, suspended for a second time after testing positive for a banned substance, has filed an appeal with USA Track and Field for a hearing.

The 1996 Atlanta gold medalist and world indoor and outdoor record holder is trying to avoid a lifetime ban after testing positive for the nutritional substance androstenedione, in an out-of-competition test in April.

Barnes was first suspended for two years in 1991 by the International Amateur Athletic Federation for using the steroid methyltestosterone.