At all times, the axes of rotation of the handholds are parallel to each other and extend along {HEAD ~ a plane} that contains {TAIL ~ the axis} of circumduction of the users shoulders 
contains
At all times , the axes of rotation of the handholds are parallel to each other and extend along { HEAD ~ a plane } that contains { TAIL ~ the axis } of circumduction of the users shoulders
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH