Relationship between hand-grip isometric strength and isokinetic moment data of the shoulder stabilisers

The purpose of this study was to examine the relationship between hand-grip (HG) isometric strength and isokinetic moment of the shoulder musculature in 18 healthy male volunteers. HG isometric strength at 0 degrees , 90 degrees and 180 degrees of shoulder flexion and isokinetic peak and average concentric moments of the shoulder rotators and abductors and the elbow flexors at 60 degrees s(-1) were measured on both the dominant and non-dominant sides. Pearson correlation coefficients revealed statistically significant positive relationships between HG isometric strength and isokinetic moments of the shoulder external rotators (r=0.40-0.54), the shoulder abductors (r=0.42-0.71) and the elbow flexors (r=0.45-0.66) regardless of hand dominance. The positive relationships between HG isometric strength and isokinetic strength of the shoulder stabilisers was probably attributed to mechanisms providing stability to the elbow and shoulder joints either by force transmission via myotendinous and myofascial pathways or by "overflow" of muscular activity via neural circuits. The results of the present findings suggested that HG isometric strength can be used to monitor isokinetic strength of certain muscle groups contributing to the stability of the shoulder joint; however, HG strength may account only for approximately 16-50% of the variability in isokinetic strength of these muscle groups.