Electrical Impedance Myography Improves Hand-Held Dynamometry Compared to Isokinetic Dynamometry in Assessment of Hamstring/Quadriceps Strength Ratio in Elite Female Football Players

Abstract

Objectives: The measurement of hamstring to quadriceps ratio (H/Q ratio) has been proposed as a possible screening tool to identify those at risk of anterior cruciate ligament injury. Unfortunately, the widespread implementation of this measurement is limited due to the lack of portability and ease of use of isokinetic dynamometry. The objective of this study was to assess the validity of using handheld dynamometry in conjunction with a new technology, electrical impedance myography, compared to isokinetic dynamometry alone to measure H/Q ratio in elite female footballers. Design: Laboratory based validity study. Methods: A convenience sample of 20 elite female footballers completed strength testing using isokinetic dynamometry and hand-held dynamometry as well as electrical impedance myography. Results: Mean H/Q ratio as measured by hand-held dynamometry was 0.68±0.14 compared to 0.54±0.07 with isokinetic dynamometry. Correlation(R) between H/Q ratio measured using hand-held dynamometry and isokinetic dynamometry was 0.21. When electrical impedance data was added the correlation improved to 0.32. Conclusions: Handheld dynamometry alone poorly predicts isokinetic dynamometry H/Q ratio. The addition of electrical impedance myography improves this relationship; however, further study is required to determine, the role, hand-held dynamometry and electrical impedance myography together can play in the measurement of H/Q ratio.