Effect of the menstrual cycle on knee joint position sense and dynamic balance

The objective of this study was to examine how the menstrual cycle affects knee joint position sense (JPS) and dynamic balance. Forty-five physically active women (age 20.87 ± 0.54 years) participated in this study. Pain was measured with a Visual Analogue Scale (VAS). Knee JPS was measured using the passive-active repositioning method using a digital inclinometer. The modified Star Excursion Balance Test was used to assess dynamic balance (SEBT). The VAS scores were higher in the menses phase compared to the mid-luteal phase (p < 0.001) and mid-follicular phase (p = 0.002). No significant differences were found between phases of the menstrual cycle for JPS in 30° (p > 0.05) and 60° of knee flexion (p > 0.05). There were significant differences in the anterior (p = 0.028), posteromedial (p < 0.001), and posterolateral (p < 0.001) directions of the modified SEBT. The values of the anterior direction in a mid-follicular phase were higher than the menses phase (p = 0.017). Mid-luteal phase values in the posteromedial direction were greater than mid-follicular phase (p = 0.008) and menses phase (p < 0.001). The values of the posterolateral direction in the mid-luteal phase (p < 0.001) and mid-follicular phase (p = 0.009) were higher than in the menses phase. In conclusion, the knee JPS did not change during the menstrual cycle in physically active women. However, the dynamic balance performance was at the lowest level in the menses phase. The risk of injury should be considered during menstruation, especially in activities that require dynamic balance skills in physically active women.