It is dangerous to assume. It is even more dangerous when you teach assumptions and hide it as truth. I think it is better to share what we know, and also what we do not know. This is what 1080 Movement Assessment Profile (1080 MAP) is based upon; the constant development of knowledge.
That is why I would like to share the kinematic results on one test that we use. We divided the body into the following segments; foot, leg, thing, pelvis, trunk (thorax and lumbar spine), head (head and cervical spine) upper arm, forearm and hand. We then modeled these segments in three dimensions in order to see what joint motions that significantly contributed to reach distance in different directions. I will not present the full analysis here, but rather show how patterns of joint excursions where consistent, and also not consistent for the 28 subjects we tested for one particular test. The one test we have chosen to describe here is standing on the left foot in the center of 1080 Mat as shown in Figure 1 below.
Figure 1. 1080 Mat
The right foot has toe touch. Then with the left hand you reach as far as you can along a 45-degree angulation to the right relative to an anteroposterior vector. The heel, big toe and little toe have to maintain contact with the ground during the test. No support on the floor with the reaching hand is allowed. The results of the joint motions utilized to accomplish, without the magnitude, are presented in Table 1 below. After each motion, in parenthesis, the number of subjects using that motion over the total number of subjects tested (n=28) is identified. Due to the complexity of calculating shoulder motions, eight different motions in three planes of motion, only selected motions were calculated.
Table 1. Coordination of joint motions
Here is a link to how we calculated kinematics for this particular reach
Overall there are consistent patterns used by almost all subjects. You will have to wait for the details in later scientific publications for a full description and analysis of the other tests