Cincinnati Children's Hospital, 3333 Burnet Avenue, MLC 10001, Cincinnati, OH 45229, USA.
Am J Sports Med. 2010 Sep;38(9):1829-37. doi: 10.1177/0363546510367425. Epub 2010 Jun 3.
Yearly changes in active joint stiffness may help explain when neuromuscular sex differences emerge in adolescent athletes that may relate to increased anterior cruciate ligament injury risk in females.
Pubertal males would demonstrate increases in knee stiffness while pubertal females would not. Second, postpubertal female athletes would have significantly lower knee joint stiffness than postpubertal male athletes.
Cohort Study; Level of Evidence 2 and Cross-Sectional Study; Level of Evidence 3.
Two hundred sixty-five females and 50 males participated in 2 testing sessions approximately 1 year apart. The subjects were classified as either pubertal (n = 182, age 12.4 +/- 0.9 years) or postpubertal (n = 133, age 14.5 +/- 1.4 years) based on the modified Pubertal Maturational Observational Scale at each visit. Active joint stiffness of the ankle, knee, and hip was estimated during a drop vertical jump. Stiffness was calculated as the slope of the moment-angle curve from a least squares linear regression during the stance phase.
All athletes showed increased active knee stiffness during the span of a year (P < 0.05). However, this increase was not different when stiffness was normalized to body mass. Only males demonstrated greater magnitudes of ankle and hip active stiffness (P < .05). Peak ankle and hip moments, but not knee moments, in postpubertal males were significantly greater than postpubertal females (P < .05). Females had a higher knee to hip moment ratio than males (P < .05).
Both males and females showed increased active knee stiffness during the span of a year; males demonstrated increased ankle and hip active stiffness as well. Differences in hip joint posture at initial contact (greater flexion in males) and external hip flexion moment (greater flexion magnitude in males) may indicate that males use a different hip recruitment strategy during drop vertical jumps than females.
活跃关节僵硬的年度变化可能有助于解释青少年运动员中何时出现神经肌肉性别差异，这些差异可能与女性前交叉韧带损伤风险增加有关。
青春期男性的膝关节僵硬会增加，而青春期女性则不会。其次，青春期后女性运动员的膝关节僵硬显著低于青春期后男性运动员。
队列研究；证据水平 2 和横断面研究；证据水平 3。
265 名女性和 50 名男性参加了大约相隔 1 年的 2 次测试。根据每次访问时的改良 Pubertal Maturational Observational Scale，受试者被分类为青春期（n = 182，年龄 12.4 ± 0.9 岁）或青春期后（n = 133，年龄 14.5 ± 1.4 岁）。在垂直跳跃下落期间，估计脚踝、膝盖和臀部的活跃关节刚度。刚度是通过在站立阶段进行最小二乘线性回归来计算的力矩-角度曲线的斜率。
所有运动员在一年内都表现出活跃膝关节刚度的增加（P < 0.05）。然而，当刚度按体重归一化时，这种增加并没有差异。只有男性表现出更大的踝关节和髋关节主动刚度（P <.05）。青春期后男性的峰值踝关节和髋关节力矩明显大于青春期后女性（P <.05）。但膝关节力矩则不然。青春期后男性的膝关节到髋关节力矩比高于女性（P <.05）。
男性和女性在一年内都表现出活跃膝关节僵硬的增加；男性还表现出踝关节和髋关节主动刚度的增加。在初始接触时髋关节姿势（男性更大的屈曲）和外部髋关节屈曲力矩（男性更大的屈曲幅度）的差异可能表明，男性在垂直跳跃下落时使用了不同于女性的髋关节募集策略。
