Inter- and intrarater reliability of four single-legged hop tests  and isokinetic muscle torque measurements in children.
OBJECTIVE
Single-legged hop tests and isokinetic muscle torque are common outcome measures in the evaluation of knee function. The reliability of the single-legged hop tests in children has not been documented. The aim was to examine inter- and intrarater reliability of four single-legged hop tests and isokinetic muscle torque measurements in children.


METHODS
Twenty-eight sports-active children (12.4 ± 0.3 years old) were tested three times in two test sessions separated by 1 week. They performed four single-legged hop tests and concentric isokinetic torque measurements during knee extension and flexion. Inter- and intrarater reliability were calculated using the intraclass correlation coefficient (ICC 2,1). Relative terms of the standard error of measurement (SEM %) and smallest real difference(SRD %) were emphasized to allow comparison between the different variables.


RESULTS
Twenty-six children were included for statistical analysis. ICCs for inter- and intrarater reliability were moderate to high for the hop tests (0.62-.91) and isokinetic measurements (0.76-0.87). SEMs % were low for the hop tests (3.9-7.4 %) and the isokinetic measurements (5.2-8.9 %). SRDs % were 20.5 % or less for the hop tests, 15.7 % or less for knee extension, and 24.6 % or less for knee flexion.


CONCLUSIONS
The single-legged hop tests and isokinetic muscle torque measurements demonstrated moderate-to high reliability with low measurement error in sports-active children. A change above 20.5 % for the single-legged hop tests, 15.7 % for knee extension, and 24.6 % for knee flexion is necessary to represent a real change in knee function. Level of evidence III.
Marianne Bakke
MB
Johnsen
Ingrid
I
Eitzen
Håvard
H
Moksnes
May Arna
MA
Risberg
D056352:Athletes; D002648:Child; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology*; D007718:Knee Injuries / Q000175:diagnosis; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009048:Motor Skills / Q000502:physiology; D053580:Muscle Strength; D015588:Observer Variation; D010808:Physical Examination / Q000592:standards*; D015203:Reproducibility of Results