Influence of menstrual cycle on the relationship between joint laxity and dynamic balance ability

Background：General joint laxity （GJL） is a physical characteristic of joint hypermobility and decreased joint support function and may be involved in sports injuries and disorders of the trunk and lower limbs. Lee et al. and Shultz et al. reported that anterior knee laxity （AKL） increases during the ovulatory and luteal phases; however, Beynnon et al. reported no cyclic changes in AKL. As a result, no consensus on the knee joint has been formed. Sung et al. reported that knee and ankle joint laxity increases during ovulation, which may affect the ability to balance. Purpose：This study aimed to clarify the effect of the menstrual cycle on AKL and balancing ability. Methods：The subjects were adult women, and AKL and modified Star Excursion Balance Test （mSEBT） scores were measured. Results：AKL and mSEBT were not significantly different between the menstrual cycles for both the dominant and non-dominant legs. The correlations between AKL and mSEBT examined for the menstrual cycle showed a trend of negative correlation in the non-dominant leg during the ovulatory phases of AKL and PM （p = 0.0863）. Conclusion：In this study, a tendency for a negative correlation was found between AKL and mSEBT during the ovulatory phase, suggesting that those with high AKL during the ovulatory phase may have a relatively low dynamic balance ability.