The effect of elbow position on the handgrip strength test in children: validity and reliability of TKK 5101 and DynX dynamometers

Background and Study Aim: One of the most widely applied methods to assess upper-body strength in children and adolescents is the handgrip strength test. While in adolescents it has been determined which elbow position, and which type of dynamometer are most appropriate for achieving the maximal grip strength, in children is still not clear. Therefore, the purpose of this study was to investigate whether elbow position and the type of dynamometer affect the handgrip strength in children. Material and Methods: Grip strength was measured by TKK and DynX dynamometers, and their validity and reliability were also analysed. A total of 60 children, 6 to 11 years old, participated in this study, and performed the handgrip strength test with their elbow extended and flexed at 90°. Results: While using the TKK dynamometer, grip strength was significantly higher when the test was performed with elbow extended, in contrast to those obtained with elbow flexed (14.58±3.04 kg vs 12.97±2.99 kg, p<0.001 for right, and 14.25±3.05 kg vs 12.61±2.99 kg, p<0.001 for left hand). Likewise, when using the DynX dynamometer, the difference between the two elbow positions was smaller but still significant (13.84±3.22 kg vs 13.35±3.01 kg, p=0.035 for right, and 13.35±2.95 kg vs 12.77±2.96 kg, p=0.003 for left hand). Conclusions: Both dynamometers provided sufficient results in terms of their reliability and the TKK dynamometer showed to be more valid. Performing the handgrip strength test with elbow extended appears to be the most appropriate position in order to obtain maximal results in children.