Final answer:
The differences in shoulder range of motion during a reaching task between individuals with previous rotator cuff tears and those with no shoulder injuries are primarily in angular motion variables, measuring the degree of rotation around an axis.
Step-by-step explanation:
When assessing the shoulder range of motion during a reaching task, it is important to compare individuals with previous rotator cuff tears to those with no shoulder injuries. The shoulder joint allows a wide range of motions, such as abduction, adduction, circumduction, and flexion-extension.
In people with previous rotator cuff injuries, these movements may be altered due to the formation of scar tissue, muscle degeneration, or changes in the shoulder joint structure, often leading to a condition known as adhesive capsulitis or “frozen shoulder”. As a result, these individuals typically experience angular motion variables that are different from those with uninjured shoulders.
An angular motion variable refers to the measurement of rotation around an axis, which in the case of the shoulder, would be the degrees through which the shoulder can move in various directions. This contrasts with linear motion, which corresponds to the movement following a straight line, and translational motion, which describes the movement of a body from one point to another.
The distinction is important because while linear and translational movements might be limited in people with shoulder injuries, it is the angular restrictions that are the immediate concern when it comes to shoulder joint injuries.
Therefore, the correct option for the differences in shoulder range of motion during a reaching task between individuals with previous rotator cuff tears and those with no shoulder injuries would be b. an angular motion variable.