Most likely a higher shutter speed will be needed, if at all possible. This is where it gets a bit tricky with slower glass - 1/125 will freeze someone moving at about a walk, but for a gymnast you'd most likely get a good amount of motion blur. Really the closer to 1/500 you can get the better but often you'll have problems in bad lighting with slow glass getting a good enough exposure that way even at high ISO. So you try to bump up as close as you can to 1/500 and the rest is mostly just luck.