In other throwing events it is common to throw in each direction. How many throws should you take in the opposite direction and how good does technique need to be in that direction? My concern is that training just to one side might provoke scoliosis or other spinal injuries. -Thomas
Throwing in the opposite direction is indeed less common in the hammer throw than in other throwing events. Tony Dziepak has compiled a list of ambidextrous throwing records which include impressive performances like Hank Kraychir putting the shot 20.55-meters with his right hand and also going over 18-meters with his left hand. With the amount of technique involved, it is natural that hammer throwers generally do not throw as much in the other direction. But in looking at the necessity of it, the same rules apply to all throwing events.