The assessments of the internal (IR) and external (ER) rotator muscle strength of the shoulder are often studied from a hand held accessory gripped. In these conditions, even if the wrist is in alignment with the radius, it is not possible to eliminate any compensatory movements of the wrist during maximal contractions of the shoulder muscle rotators. The objective of this study was to investigate the movements of the wrist in flexion/extension during an isokinetic assessment of the strength of shoulder rotators.

Twenty-two healthy participants were explored. Participant previously installed in a seated position, the shoulder test was performed for IR and ER in concentric (CON) and eccentric (ECC) modes on each shoulder (dominant: D; non-dominant: ND), at 60°/s and 180°/s using an isokinetic dynamometer and an electronic goniometer fixed on the wrist. Data acquisition was recorded continuously and calculated with an analysis software.

No significant difference founded in wrist mobility depending on muscle groups (IR or ER) and laterality (D or ND) whereas dominant PT was higher at all velocity for ER (in CON and ECC modes) and for IR ECC. No significant correlation between the movements of the wrist and the strength parameters was shown. However, the wrist movements were greater in the concentric modality (P<0.05). In addition, we observed a significant difference (P<0.05) between angular velocities for the ND side, with greater movements at low speed (60°/s).

These results highlight compensation strategies of the wrist during isokinetic assessment of the shoulder depending on modality of contraction with a locking strategy in ECC mode, and angular velocity selected. To conclude, isokinetic assessment is to evaluate the muscle potential of an isolated joint by limiting the compensation, but it is important to focus on the surrounding joints due to the fact that the human body is a set of interacting segments with interconnected influences.