Friesen Kenzie B, Shaw Regan E, Shannon David M, Dugas Jeffrey R, Andrews James R, Oliver Gretchen D
College of Kinesiology, University of Saskatchewan, Saskatchewan, Canada.
Sports Medicine and Movement Lab, School of Kinesiology, Auburn University, Auburn, Alabama, USA.
Orthop J Sports Med. 2021 Mar 23;9(3):2325967121990920. doi: 10.1177/2325967121990920. eCollection 2021 Mar.
A lack of lumbopelvic-hip complex (LPHC) stability is often associated with altered pitching mechanics, thus increasing pain and injury susceptibility. The single-leg squat (SLS) is a simple diagnostic tool used to examine LPHC stability.
To examine the relationship between trunk compensatory kinematics during the SLS and kinematics at foot contact during the windmill pitch.
Descriptive laboratory study.
Participants included 55 youth and high school softball pitchers (mean age, 12.6 ± 2.2 years; height, 160.0 ± 11.0 cm; weight, 60.8 ± 15.5 kg). Kinematic data were collected at 100 Hz using an electromagnetic tracking device. Participants were asked to complete an SLS on each leg, then throw 3 fastballs at maximal effort. Values of trunk flexion, trunk lateral flexion, and trunk rotation at peak depth of the SLS were used as the dependent variables in 3 separate backward-elimination regression analyses. Independent variables examined at foot contact of the pitch were as follows: trunk flexion, trunk lateral flexion, trunk rotation, center of mass, stride length, and stride knee valgus.
The SLS trunk rotation regression ((1,56) = 4.980, = .030) revealed that trunk flexion predicted SLS trunk rotation (SE = 0.068, = 2.232, = .030) and explained approximately 7% of the variance in SLS trunk rotation ( = 0.083, adjusted = 0.066). The SLS trunk flexion regression ((1,56) = 5.755, = 0.020) revealed that stride knee valgus significantly predicted SLS trunk flexion (SE = 0.256, = 2.399, = .020) and explained approximately 8% of variance in SLS trunk flexion ( = 0.095, adjusted = 0.078).
Additional trunk rotation and trunk flexion at peak depth of the SLS showed increased knee valgus and trunk flexion at foot contact of the pitch, both of which indicate poor LPHC stability during the softball pitch and may increase the potential for injury.
Players and coaches should implement SLS analyses to determine their players' risk for injury and compensation due to poor core stability.
腰骶骨盆髋关节复合体（LPHC）稳定性不足常与投球力学改变相关，进而增加疼痛和受伤易感性。单腿深蹲（SLS）是用于检查LPHC稳定性的一种简单诊断工具。
研究单腿深蹲期间躯干代偿性运动学与风车式投球时脚触地瞬间运动学之间的关系。
描述性实验室研究。
参与者包括55名青少年和高中垒球投手（平均年龄12.6±2.2岁；身高160.0±11.0厘米；体重60.8±15.5千克）。使用电磁跟踪设备以100赫兹的频率收集运动学数据。要求参与者每条腿各完成一次单腿深蹲，然后尽全力投出3个快球。单腿深蹲最大深度时的躯干前屈、躯干侧屈和躯干旋转值在3项独立的向后逐步回归分析中用作因变量。在投球脚触地时检查的自变量如下：躯干前屈、躯干侧屈、躯干旋转、重心、步长和步幅膝外翻。
单腿深蹲躯干旋转回归分析（(1,56)=4.980，P=.030）显示，躯干前屈可预测单腿深蹲时的躯干旋转（标准误=0.068，β=2.232，P=.030），并解释了单腿深蹲躯干旋转约7%的方差（R²=0.083，调整后R²=0.066）。单腿深蹲躯干前屈回归分析（(1,56)=5.755，P=0.020）显示，步幅膝外翻显著预测单腿深蹲时的躯干前屈（标准误=0.256，β=2.399，P=.020），并解释了单腿深蹲躯干前屈约8%的方差（R²=0.095，调整后R²=0.078）。
单腿深蹲最大深度时额外的躯干旋转和躯干前屈表明在投球脚触地时膝外翻增加和躯干前屈增加，这两者均表明垒球投球过程中LPHC稳定性较差，可能会增加受伤风险。
运动员和教练应进行单腿深蹲分析，以确定运动员因核心稳定性差而受伤和代偿的风险。
