Eiling E, Bryant A L, Petersen W, Murphy A, Hohmann E
Department of Orthopaedic Surgery, Kiel University, Kiel, Germany.
Knee Surg Sports Traumatol Arthrosc. 2007 Feb;15(2):126-32. doi: 10.1007/s00167-006-0143-5. Epub 2006 Jul 5.
The high risk of anterior cruciate ligament (ACL) injuries in female athletes may be related to hormonal fluctuations resulting in an increased laxity of ligaments and muscles. This study examined changes in lower limb musculotendinous stiffness (MTS) and knee laxity over the course of the menstrual cycle and investigated the interaction of warm-up on MTS. Eleven female netball players aged 16-18 years who were not using hormonal contraceptives and demonstrated regular menstrual cycles participated in this study. Test-sessions were conducted at onset of menses, mid-follicular phase, ovulation and mid-luteal phase. ACL laxity was determined at each test-session using a KT2000 knee arthrometer. MTS was assessed prior to, and following a standardised warm-up. Repeated measures ANOVA revealed significant (P < 0.05) main effects of test-session and warm-up on MTS. MTS was found to significantly decrease by 4.2% following the warm-up intervention. MTS was significantly lower at week 3 (ovulatory phase) in contrast to weeks 1 and 2 (8.7 and 4.5%, respectively). For knee laxity measures, repeated measures ANOVA revealed no significant (P < 0.05) differences across the menstrual cycle. A reduction in MTS results in greater reliance on reflexive response from the contractile components of the muscle due to a decreased contribution from passive elastic structures and will also increase electromechanical delay. Given that extreme loads are applied to the knee joint within milliseconds, the contractile components cannot respond quickly enough to counteract these sudden and potentially damaging forces. These effects are augmented following a moderate warm-up. Oestrogen fluctuations had no significant effect on anterior knee laxity, however, the effects on MTS over the 28-day cycle were considerable. Future studies should use matched subjects who are using the monophasic oral contraceptive pill to investigate the effects of oestrogen supplementation on lower limb MTS.
女性运动员前交叉韧带（ACL）损伤风险较高，可能与激素波动导致韧带和肌肉松弛增加有关。本研究考察了月经周期过程中下肢肌肉肌腱僵硬度（MTS）和膝关节松弛度的变化，并研究了热身对MTS的影响。11名年龄在16 - 18岁、未使用激素避孕药且月经周期规律的女子无挡板篮球运动员参与了本研究。测试在月经开始时、卵泡中期、排卵期和黄体中期进行。每次测试时使用KT2000膝关节测径仪测定ACL松弛度。在标准化热身前后评估MTS。重复测量方差分析显示测试阶段和热身对MTS有显著（P < 0.05）的主效应。发现热身干预后MTS显著降低了4.2%。与第1周和第2周相比，第3周（排卵期）MTS显著更低（分别为8.7%和4.5%）。对于膝关节松弛度测量，重复测量方差分析显示整个月经周期无显著（P < 0.05）差异。MTS降低导致由于被动弹性结构贡献减少而更依赖肌肉收缩成分的反射性反应，并且还会增加机电延迟。鉴于在数毫秒内膝关节会承受极大负荷，收缩成分无法足够迅速地做出反应以抵消这些突然且可能具有破坏性的力量。适度热身会增强这些影响。雌激素波动对膝关节前侧松弛度无显著影响，然而，在28天周期内对MTS的影响相当大。未来研究应使用服用单相口服避孕药的匹配受试者来研究雌激素补充对下肢MTS的影响。
