J Sport Rehabil. 2019 Jul 1;28(5):413-420. doi: 10.1123/jsr.2017-0132. Epub 2018 Dec 4.
Strength, functional performance, and limb symmetry are common objective clinical assessments used by clinicians to guide safe return to physical activity following injury. Population-specific unilateral limb outcomes or estimates of limb symmetry of these assessments should be established. To compare lower-extremity strength, functional performance, and limb symmetry in healthy participants based on sex and level of activity. Descriptive laboratory study. Laboratory. A total of 117 healthy participants (72 males and 45 females; mass = 73.67 [13.60] kg, height = 1.76 [0.12] m, and age = 21.44 [2.92] y) without history of injury within 6 months were included. Participants completed isokinetic concentric and isometric knee extension and flexion strength tasks at 90°/s, 180°/s, and 90°, respectively, and 4 hop tasks (single, cross-over, triple, and 6-m timed) during 1 session. Groups were separated by sex (male and female) and activity level (athlete and nonathlete). Participants rostered on National Collegiate Athletic Association (NCAA) Division I (DI) teams were considered as athletes, and non-NCAA DI healthy, uninjured participants were considered as nonathletes. Limb symmetry index (LSI), maximal voluntary isometric contraction (N·m/kg), peak torque (N·m/kg), average power (N·m/s), distance (m), and time hopped (s) were assessed. LSI was calculated by dividing the lower limb outcome by the higher limb outcome of the nondominant or dominant limb. Group differences were assessed through Mann-Whitney tests and Cohen's effect sizes for all comparisons. LSI differences did not exist between groups. Mean LSIs for all participants ranged between 83.52% (12.54%) and 96.16% (3.82%). On average, males were stronger (range: = 0.63-1.54), hopped farther (range: = 1.52-1.63), and hopped faster (range: = 1.67-1.68) than females. On average, some strength differences existed between athletes and nonathletes, but athletes hopped farther (range: = 0.71-0.82) and faster (range: = 0.87-0.88) than nonathletes. Unilateral limb strength and functional performance outcomes differ between sex and activity level, but not limb symmetry. These differences may be important for a clinician's understanding of normative values of common return-to-play assessment tasks.
力量、功能表现和肢体对称性是临床医生用于指导受伤后安全恢复身体活动的常见客观临床评估。应该建立特定于人群的单侧肢体结果或这些评估的肢体对称性估计值。
本研究旨在基于性别和活动水平比较健康参与者的下肢力量、功能表现和肢体对称性。
描述性实验室研究。
实验室。共纳入 117 名健康参与者（72 名男性和 45 名女性；体重=73.67 [13.60] kg，身高=1.76 [0.12] m，年龄=21.44 [2.92] y），他们在 6 个月内没有受伤史。参与者在 1 次测试中分别完成了 90°/s、180°/s 和 90°的等速向心和等长膝关节伸展和屈曲力量任务，以及 4 项跳跃任务（单腿、交叉、双腿和 6 米计时）。根据性别（男性和女性）和活动水平（运动员和非运动员）将参与者分组。参加美国大学体育协会（NCAA）一级（DI）运动队的参与者被认为是运动员，而非 NCAA DI 的健康、未受伤的参与者被认为是非运动员。
肢体对称性指数（LSI）、最大自主等长收缩（N·m/kg）、峰值扭矩（N·m/kg）、平均功率（N·m/s）、距离（m）和跳跃时间（s）进行了评估。LSI 通过将非优势或优势肢体的下肢结果除以优势肢体的下肢结果来计算。通过曼-惠特尼 U 检验和科恩效应大小对所有比较进行了组间差异评估。
组间没有 LSI 差异。所有参与者的平均 LSI 范围为 83.52%（12.54%）至 96.16%（3.82%）。平均而言，男性力量更强（范围：=0.63-1.54），跳跃距离更远（范围：=1.52-1.63），跳跃速度更快（范围：=1.67-1.68）。平均而言，运动员和非运动员之间存在一些力量差异，但运动员跳跃距离更远（范围：=0.71-0.82），跳跃速度更快（范围：=0.87-0.88）。
下肢力量和功能表现结果因性别和活动水平而异，但肢体对称性没有差异。这些差异对于临床医生了解常见重返运动评估任务的正常值可能很重要。
