Because we are only discussing one variable at this time (height), consider the following ergonomic principles: 1) all work activities should permit the worker to adopt several different, but equally healthy and safe postures 2) where muscular force has to be exerted it should be done by the largest appropriate muscle groups available. 3) work activities should be performed with the joints at about mid-point of their range of movement. This applies particularly to the head, trunk, and upper limbs. If possible, position the center of the reel six inches below your belt.