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