The Effects of Fatigue on Knee Joint Position Sense in Female Athletes
Keywords:proprioception, knee joint position sense, women athletes, fatigue, estrogen, progesterone
The effects of muscle fatigue include a decrease of angle position sense (proprioception) and a decrease of movement control in static balance examination. It has been reported that when the values of estrogen and progesterone increase, kinesthesia and neuromuscular coordination decrease. The aim of this study was to examine the possible effect of menstrual cycle phases on the angle position sense of the knee joint before and after fatigue of the knee’s extensor and flexor muscles. Ten women athletes, 18-25 years old, (height 164.2 ± 9.2 cm, weight 59.5 ± 5.5 Kg, and percentage of body fat 21.2 ± 4.5% volunteered for this study. An isokinetic dynamometer (CYBEX®, Ronkokoma, NY) was used to evaluate angle position sense and to perform a fatigue protocol. We measured knee joint position sense at rest and after a fatigue protocol of the knee extensors and flexors, at 3 knee flexion’s target angles, 30º, 45º and 60º, (with the full extension taken as 0º position). We used a statistical analysis of variance in repeated measures with two factors (2x2). A non-statistically significant effect of menstrual phases was observed in knee joint position sense in 45ο (p>.05) and in 30ο (p>.05), at rest and at fatigue. There was no statistically significant interaction between the phase of menstrual cycle and fatigue in 45ο and 30 ο (p>.05). Fatigue significantly affected knee joint position sense at 60ο (p=.041), in both phases of the menstrual cycle. The main effect of the menstrual
phases on knee joint position sense at 60ο, while apparent, was not statistically significant (p=.082). We found no statistically significant interaction between the phase of menstrual cycle and fatigue, at 60ο (p>.05). Based on our results, the phase of the menstrual cycle seems not to affect knee joint position sense in the examined angles (30º, 45º and 60º). The effect of the localized fatigue protocol on the knee joint position sense seems to depend on the examined knee joint angle and appears independent of the menstrual cycle phase.