Hannah Ricci, Folland Jonathan P, Smith Stephanie L, Minshull Claire
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, 146, Queen Square, London, WC1 3BG, UK,
Eur J Appl Physiol. 2015 Apr;115(4):837-47. doi: 10.1007/s00421-014-3063-y. Epub 2014 Dec 5.
Females are known to exhibit a greater risk of ACL injury compared to males. Lower explosive hamstrings-to-quadriceps (H/Q) force ratio in the first 150 ms from activation onset could reflect an impaired capacity for knee joint stabilisation and increased risk of ACL injury. However, the explosive H/Q force ratio has not been compared between the sexes.
The neuromuscular performance of untrained males and females (20 of each) was assessed during a series of isometric knee flexor and extensor contractions, specifically explosive and maximum voluntary contractions of each muscle group. Force, in absolute terms and normalised to body mass, and surface EMG of the hamstrings and quadriceps were recorded. Hamstrings force was expressed relative to quadriceps force to produce ratios of explosive H/Q force and H/Q maximum voluntary force (MVF). For the explosive contractions, agonist electromechanical delay (EMD) and agonist neural activation were also assessed.
The H/Q MVF ratio was greater in males (56 %) than females (50 %; P < 0.001). However, the explosive H/Q force ratio was similar between the sexes at each time point (25-150 ms) from activation onset. Explosive hamstrings, but not quadriceps, force relative to body mass was greater for males compared to females. There were no sex differences in EMD or agonist activation for either of the muscle groups.
The lack of a sex difference in early phase isometric explosive H/Q force ratio suggests other factors might be more important in determining the substantially higher knee injury rates of females.
已知女性与男性相比，前交叉韧带（ACL）损伤风险更高。激活开始后的前150毫秒内，较低的爆发力腘绳肌与股四头肌（H/Q）力量比可能反映膝关节稳定能力受损以及ACL损伤风险增加。然而，爆发力H/Q力量比尚未在不同性别之间进行比较。
在一系列等长膝关节屈伸收缩过程中，评估未经训练的男性和女性（各20名）的神经肌肉表现，具体为每个肌肉群的爆发性和最大自主收缩。记录绝对力量、按体重标准化的力量以及腘绳肌和股四头肌的表面肌电图。腘绳肌力量相对于股四头肌力量表示，以得出爆发性H/Q力量比和H/Q最大自主力量（MVF）比。对于爆发性收缩，还评估了激动剂机电延迟（EMD）和激动剂神经激活情况。
男性的H/Q MVF比（56%）高于女性（50%；P<0.001）。然而，从激活开始的每个时间点（25 - 150毫秒），两性之间的爆发性H/Q力量比相似。与女性相比，男性相对于体重的爆发性腘绳肌力量更大，但股四头肌力量并非如此。两组肌肉在EMD或激动剂激活方面均无性别差异。
早期等长爆发性H/Q力量比不存在性别差异，这表明在决定女性显著更高的膝关节损伤率方面，其他因素可能更为重要。
