Context: Previous authors suggest that lack of strength is an important risk factor for injuries in water polo. Hand-held dynamometers have potential as a clinical tool to measure strength, but they have not been validated in water polo players.
Objective: The purpose of this study was to estimate intertrial variability and concurrent validity of hand-held dynamometer shoulder strength measurements in elite water polo players.
Methods: A total of 19 male and 20 female elite water polo players performed isometric external (ER) and internal (IR) rotation strength tests against a hand-held dynamometer bilaterally in supine position with the shoulder in a 90-90 position. In addition, concentric IR and ER was captured at 90 deg/s with an isokinetic dynamometer, and torque values were determined near the 90-90 position.
Main outcome measures: Spearman correlation coefficients were calculated for ER torque, IR torque, and ER/IR ratios between the devices. Two-way mixed-model intraclass correlations were used to assess intertrial variability.
Results: Correlations between the devices were strong to very strong (ρ = .65-.82, P < .01) for absolute IR and ER but low for ER/IR ratios (ρ = .29, P = .07). There was less agreement at higher torque values. Intertrial variability was low with intraclass correlation values .88 to .93, P < .05.
Conclusions: These results show that hand-held dynamometers are adequate clinical alternatives to measure absolute shoulder strength in water polo players. Stronger players may require stronger evaluators to resist the player's push and obtain reliable results.
Keywords: aquatic; athlete; dynamometer.