Internal/External Rotations

The position of the scapula needs to be set before movements take place. I recommend a scapula angle of 15 degrees (see below) as this offers the best alignment for the rotations to occur with minimal scapula involvement.

The next consideration is the angle of the gleno-humoral joint. Most authors recommend neutral as the optimal position but I find this impossible to achieve so I am always guided by subject comfort. Either of the positions shown below are adequate.

Some clinicians use a spirit level to align the humerous to level with the floor but I prefer a position somewhere near 75 degrees abduction (remember consistency is the key!). The elbow should be flexed to 90 degrees (see below).

Once the position of the scapula and gleno-humeral joint neutral has been reached then the actuator should already be co-linear with that of the humerus through the olecranon (Wilk et al. 1991). Or in other words once you have the subject in place the elbow will be opposite the actuator axis as the designers have made it that way. Stabilization is achieved with thoracic strapping.

As velocities in some sports (any involving throwing an object) are known to reach thousands of degrees/second (Pappas et al., 1985) testing using a dynamometer will never be functional. (Even if this speed could be achieved it is over such a small arc that the results gained would be fruitless.) Generally it is accepted that speeds of 60 degrees/second and multiples of this should be used. Speeds over 300 degrees/second have been found to be difficult to achieve by even baseball pitchers (Cook et al., 1987).