背景:前臂屈前肌在棒球投球过程中充当对抗肘部外翻负荷的动态肘部稳定器。这些肌肉的弹性随着俯仰而增加。然而,目前尚不清楚肌肉弹性的增加是否与俯仰时肘部外翻扭矩的增加有关。这项研究旨在确定年轻棒球投手投球过程中前臂屈前肌的弹性与肘部外翻扭矩之间的关系。
方法:我们招募了124名9至12岁的年轻棒球投手。排除标准包括当前的俯仰疼痛,被测试肢体的手术史,或在过去12个月内受测肢体受伤。考试前,参与者填写了一份关于他们年龄的问卷,高度,体重,支配手臂和每周练习时间。尺侧腕屈肌应变比(FCU),指浅屈肌(FDS),使用超声应变弹性成像测量肌肉弹性指数。参与者以最大的努力在52英尺6英寸(16m)的距离投下三个快球,同时佩戴记录肘部外翻扭矩的传感器套筒。进行了多元线性回归分析,以检查肌肉弹性与肘部外翻扭矩之间的关联。调整年龄,高度,体重,练习时间。
结果:最终分析包括107个投手。在调整协变量后,FCU的应变比增加与更大的肘部外翻扭矩显著相关(系数=0.038,95%置信区间[CI],0.016-0.059,P<.001)。同样,FDS应变比的增加与肘部外翻扭矩的增加显著相关(系数=0.027,95%CI,0.013-0.042,P<.001).
结论:在年轻棒球投手投球过程中,FCU和FDS的高弹性与较大的肘部外翻扭矩相关。这些肌肉的高弹性是一种保护性反应,对于在投球过程中肘部外翻扭矩更大的年轻棒球投手来说可能是必要的。在肘部外翻扭矩更大的年轻棒球投手中,那些无法产生这些肌肉较高弹性的人在投球时可能会有更大的肘部外翻负荷,肘部受伤的风险更高。FCU和FDS的弹性测量可能有助于识别有肘部受伤风险的年轻棒球投手。
BACKGROUND: The forearm flexor-pronator muscles act as a dynamic elbow stabilizer against elbow valgus load during baseball pitching. The elasticity of these muscles increases with pitching. However, it is unclear whether increased muscle elasticity is associated with greater elbow valgus torque during pitching. This study aimed to determine the relationship between the elasticity of the forearm flexor-pronator muscles and elbow valgus torque during pitching in young baseball pitchers.
METHODS: We recruited 124 young baseball pitchers aged 9 to 12 years. The exclusion criteria included current pain with pitching, history of surgery on the tested extremity, or injuries on the tested extremity within the past 12 months. Before the examination, participants completed a questionnaire about their age, height, weight, dominant arm, and practice time per week. The strain ratios of flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), and pronator teres as the index of muscle elasticity were measured using ultrasound strain elastography. Participants pitched 3 fastballs at a distance of 16 m (52 ft 6 in) with maximum effort while wearing a sensor sleeve that recorded the elbow valgus torque. A multiple linear regression analysis was conducted to examine the association between muscle elasticity and elbow valgus torque, adjusting for age, height, weight, and practice time.
RESULTS: The final analysis included 107 pitchers. After adjusting for covariates, increased strain ratio of the FCU was significantly associated with greater elbow valgus torque (coefficients = 0.038, 95% confidence interval, 0.016-0.059, P < .001). Similarly, increased strain ratio of the FDS was significantly associated with greater elbow valgus torque (coefficients = 0.027, 95% confidence interval, 0.013-0.042, P < .001).
CONCLUSIONS: The high elasticities of the FCU and FDS were associated with greater elbow valgus torque during pitching in young baseball pitchers. The high elasticity of these muscles is a protective response and may be necessary for young baseball pitchers with greater elbow valgus torque during pitching. Among young baseball pitchers with greater elbow valgus torque, those who are unable to produce the higher elasticities of these muscles could have greater elbow valgus load during pitching and be at a higher risk for elbow injuries. The measurement of the elasticities of the FCU and FDS may be useful for identifying young baseball pitchers at risk of sustaining elbow injuries.