Validation of Electrogoniometry for the Assessment of Countermovement Jump and Landing Knee Angle

Abstract

Knee angle influences jump performance and landing kinetics. Knee flexion angle during landing is important for ACL injury risk assessment. Video analysis of jumping and landing characteristics relies on costly cameras and labor intensive analyses. Electrogoniometry is relatively inexpensive compared to video analysis and provides instantaneous angle quantification; however, electrogoniometry has yet to be validated to quantify knee angle during jumping. PURPOSE: To validate the use of electrogoniometry to assess countermovement jump and landing knee angle in the sagittal plane. METHODS: Twenty-two recreationally active men and women (21.25 ± 1.12 yrs) performed 3 countermovement jumps while knee angle was simultaneously assessed using biaxial electrogoniometry and video analysis (600fps). Root mean square error was used to compare the accuracy and reliability of electrogoniometry from the initiation of the movement to the lowest point of the center of mass during the landing. Additionally, a two-way repeated measures ANOVA was used to compare the differences between electrogoniometry and video for maximum countermovement and landing knee flexion angle and angle at maximum vertical ground reaction force. RESULTS: The average error of electrogoniometry derived knee angle throughout the entire movement was 7.03 ± 2.69°. Excellent reliability was demonstrated by the electrogoniometer (ICCsingle = 0.875; ICCavg = 0.954). However, significant differences in root mean square error between the two instruments were found between trials 1 and 3 (p = 0.019). Maximum countermovement knee angle, maximum landing knee angle and angle at maximum vertical ground reaction force were 12.0, 10.9, and 5.7° higher, respectively, when assessed using electrogoniometry (p < 0.001). CONCLUSIONS: Precise calibration and attachment of the electrogoniometer to the lower limb may enhance accuracy and reliability. The electrogoniometer can be a cost effective and time efficient alternative to video analysis if the error is accounted for.