Department of Orthopedic Surgery, Seoul National University Bundang Hospital, Seongnam, Korea.
Department of Orthopedic Surgery, Yeson Hospital, Bucheon, Korea.
Clin Orthop Surg. 2021 Sep;13(3):385-394. doi: 10.4055/cios20187. Epub 2021 Apr 13.
Baseball players are subjected to repeated loads on the supraspinatus and long head biceps tendon from youth, and repetitive pitching motions can cause shoulder injuries. The purpose of this study was to evaluate the immediate changes caused by pitching in the supraspinatus muscle-tendon, long head of the bicep tendon (LHBT), and shoulder range of motion (ROM) and to verify their recovery over time in youth baseball players.
Fifteen youth baseball players (mean age, 11.5 ± 1.3 years) were enrolled. The thicknesses of the supraspinatus tendon and LHBT and the strain ratios (SRs) of supraspinatus muscle and tendon were measured by sonoelastography. ROMs of shoulder joints (abduction, external rotation at 90° of abduction [ABER], and internal rotations at 90° of abduction [ABIR]) and horizontal adduction (HA) were measured using a goniometer. All measurements were performed on the throwing shoulders before and immediately after pitching (mean pitch count, 78.3 ± 13.3) and at 30 minutes, 24 hours, and 72 hours after pitching.
The thickness of supraspinatus tendon (6.64-6.27 mm, = 0.026) and that of LHBT (2.56-2.26 mm, = 0.021) significantly decreased immediately after pitching. The SRs of supraspinatus muscle tended to decrease, whereas SRs of supraspinatus tendon tended to increase immediately after pitching. ABER increased (119.7°-127.3°, = 0.001) and HA decreased (34.7°-29.3°, = 0.023) immediately after pitching. All immediate changes recovered 72 hours after pitching.
The immediate effects of pitching on the supraspinatus muscle-tendon, LHBT, and shoulder ROM in youth baseball players were confirmed in the current study. These changes were recovered to pre-pitch levels 72 hours after pitching. Therefore, we recommend that youth baseball players should rest for three days after pitching to minimize the risk of shoulder injury.
棒球运动员从年轻时就会反复受到来自肩袖的冈上肌和肱二头肌长头的负荷，并且反复的投掷动作会导致肩部受伤。本研究的目的是评估投球对冈上肌肌腱、肱二头肌长头（LHBT）和肩部活动范围（ROM）的即时变化，并验证它们在青年棒球运动员中的随时间恢复情况。
共纳入 15 名青年棒球运动员（平均年龄 11.5±1.3 岁）。通过超声弹性成像测量冈上肌腱和 LHBT 的厚度以及冈上肌和肌腱的应变比（SR）。使用量角器测量肩关节的 ROM（外展、外展 90°时的外旋[ABER]和外展 90°时的内旋[ABIR]）和水平内收（HA）。所有测量均在投球前（投球次数平均为 78.3±13.3 次）、投球后即刻以及投球后 30 分钟、24 小时和 72 小时进行。
冈上肌腱厚度（6.64-6.27mm， = 0.026）和 LHBT 厚度（2.56-2.26mm， = 0.021）在投球后即刻明显下降。冈上肌的 SR 倾向于下降，而冈上肌腱的 SR 倾向于上升。ABER 增加（119.7°-127.3°， = 0.001），HA 减少（34.7°-29.3°， = 0.023），均在投球后即刻发生。所有即刻变化在投球后 72 小时恢复。
本研究证实了投球对青年棒球运动员冈上肌肌腱、LHBT 和肩部 ROM 的即时影响。这些变化在投球后 72 小时恢复到投球前水平。因此，我们建议青年棒球运动员在投球后休息三天，以最大程度地降低肩部受伤的风险。
