Updated: Jan 28, 2019
In the SCA, Kingdom of An Tir, the center of a target for axe or knife must be between 40 and 60 inches above the ground. To achieve the highest scores, I've found it best to throw at a target that is as close to shoulder height as possible. This way you are not throwing 'uphill' or 'downhill' but straight from shoulder to target. At 6' 4" I try to throw at a target with a 5' center height (60 inches). My scores are about 5 points per weapon higher at this height than at 40 inches. I've also thrown with several people whose scores will drop by several points by trying to throw uphill to a 5' target.