The effect of positioning, sex and leg dominance on the plantar and dorsal flexors strength at the ankle

In the last decade, more attention is drawn to the complex function of the ankle joint. Isokinetic devices provide an objective and standardised protocol to evaluate the functional plantar and dorsal flexors strength at the ankle. The purpose of this study is to document the effect of positioning, sex and leg dominance on the plantar and dorsal flexion strength. Forty-six subjects (26 females, 20 males) were participated in this study on voluntary base (age range 19-31 year). They were in no way engaged in sports competitions. Isokinetic data was collected using a cybex-II dynamometer at two speeds (60 and 120 degrees/s) and in two positions (prone with extended knee and supine with 90 degrees flexion at the knee and 45 degrees at the hip). Statistical analysis of the peak torque to body weight ratio has revealed significant differences for the plantar as well as the dorsal flexors at 60 degrees/s and 120 degrees/s, with higher values in the prone extended position. We have only found differences between sexes in dorsal flexion at 60 degrees/s for both legs in both positions. No significant differences were obtained between extremities. These findings suggest that plantar and dorsal flexion strength depend on the test position. Sex was a significant factor for dorsal flexion strength at 60 degrees/s. The lack of differences between both legs is an advantage in pathological situations. The non affected limb can be used as a control value. We prefer the prone position with extended knee. Factors that influenced our conclusion are higher strength, better standardisation and better patient comfort.