What is normal isokinetic shoulder strength or strength ratios? A systematic review

Purpose: To systematically review the literature regarding isokinetic testing to identify values for isokinetic shoulder strength and agonist/antagonist ratios in the general population which may be used as reference values when assessing, planning and implementing shoulder rehabilitation. Methods: Electronic databases were systematically searched and reference lists of all retrieved papers were hand searched and nine relevant studies were identified. Two independent reviewers assessed methodological quality and extracted data. Results: Seven studies reported the effect of limb dominance on strength with four reporting no significant difference between the dominant and non-dominant limbs. The studies which compared muscle strength with gender concluded that men were significantly stronger than women at all speeds in all directions. Age was reported to have no significant effect on muscle strength. Four studies agreed that adduction and extension muscle strength were greater than other directions and flexion, abduction, internal rotation and external rotation were the next strongest in that order. Conclusions: Nine low and moderate quality research papers have attempted to establish isokinetic shoulder strength in a general population. Poor consistency with respect to sample sizes, randomization and selection of testing velocities and positions did not allow direct comparison of the results. Future research involving symptomatic subjects will need to be matched to a group of subjects from the general population of the same age, gender and physical profile with adequate sample sizes representative of the symptomatic population.