Resumen de Elbow Position Affects Handgrip Strength in Adolescents: Validity and Reliability of Jamar, DynEx, and TKK Dynamometers

Vanesa España Romero, Francisco Bartolomé Ortega Porcel, Germán Vicente Rodriguez, Enrique G. Artero, J. Pablo Rey, Jonatan Ruíz Ruíz

• We examined whether elbow position affects the handgrip strength in adolescents. The criterion-related validity and reliability of the Jamar, DynEx, and TKK dynamometers were also analyzed. A total of 66 adolescents aged 12 to16 years performed the handgrip strength test with the elbow extended and flexed at 90°. The validity and reliability of the Jamar, DynEx, and TKK dynamometers was analysed by using known weights. The highest score was obtained when the test was performed with the elbow in full extension and when using the TKK dynamometer. The criterion-related validity analyses showed a systematic bias of -1.92, -1.43, and 0.49 kg for the Jamar, DynEx, and TKK dynamometers, respectively (all p < 0.05). The reliability analyses revealed a systematic bias of 0.23, 0.26, and 0.02 kg in the Jamar, DynEx, and TKK dynamometers, respectively (all p > 0.05). Performing the handgrip strength test with the elbow extended appears the most appropriate protocol to evaluate maximal handgrip strength in adolescents when using the TKK. In addition, the TKK dynamometer appears to provide the highest criterion-related validity and reliability. The present study provides useful and relevant information indicating which elbow position, and which type of dynamometer, yield maximal handgrip strength in adolescents.