A study of was done comparing the performance of athletics competitors at the 1984 Summer Paralympics. It found there was no significant difference in performance in times between women in A1, A2 and A3 in the discus, women in A1 and A2 in the javelin, women in A1 and A2 in the 100 meter race, men in A1, A2 and A3 in the discus, men in A1, A2, A3, A4, A5, A6, A7, A8 and A9 in the javelin, men in A1, A2 and A3 in the shot put, men in A1 and A2 in the 100 meter race, and men in A1, A2, A3 and A4 in the 400 meter race. Double below the knee amputees also have a competitive advantage when compared to double above the knee amputees. From the 2004 Summer Paralympics to the 2012 Summer Paralympics, there was no significant changes in performance times put up by male sprinters in 100 meter, 200 meter and 400 meter events.