Schubert Manuel F, Awan Tariq M, Sciascia Aaron D, Figueroa Emily G, DeMink Jennifer M, Selak David M, Snyder Corey M, Gagnier Joel J, Freehill Michael T
Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan, USA.
Department of Orthopaedic Surgery, Detroit Medical Center, Detroit, Michigan, USA.
Orthop J Sports Med. 2024 Jun 18;12(6):23259671241256294. doi: 10.1177/23259671241256294. eCollection 2024 Jun.
Ulnar collateral ligament (UCL) injuries in youth pitchers continue to be concerning despite the institution of pitch count limits. Flexor-pronator mass fatigue can lead to diminished dynamic stability, resulting in greater stress on the UCL.
PURPOSE/HYPOTHESIS: To evaluate fatigue of the flexor-pronator mass by assessing changes in medial elbow laxity; noninvasively characterizing alterations in muscle glycogen; and identifying changes in subjective fatigue, strength, range of motion (ROM), pitching velocity, and accuracy with increasing pitches thrown by youth pitchers to their recommended 75-pitch count limit. It was hypothesized that, with increased pitches, medial elbow laxity would increase and that the glycogen content of the flexor-pronator mass would decrease.
Descriptive laboratory study.
Healthy male pitchers aged 10 years (n = 22) threw 3 sets of 25 pitches with 12 minutes between sets (3 timepoints). Bilateral ulnohumeral joint gapping was measured by applying a standardized valgus force and utilizing ultrasound imaging. Relative changes in muscle glycogen in the bilateral flexor carpi radialis (FCR), and the flexor digitorum superficialis/flexor carpi ulnaris (FDS/FCU) muscles were measured with ultrasound software and recorded as fuel percentiles. Additional measures obtained included subjective fatigue, strength, ROM, velocity, and accuracy.
There were no differences in medial elbow joint-line gapping between the throwing and nonthrowing arms or between timepoints. The throwing arm demonstrated a significant decline in fuel percentile of the FCR from baseline to after 75 pitches ( = .05). There were no differences across timepoints for FDS/FCU fuel percentile values. Fatigue measurements for both arms were significantly higher at all timepoints compared with baseline (≤ .03). Grip strength of the dominant arm after 75 pitches was decreased significantly compared with after 25 pitches ( = .02).
Although an increase in medial elbow joint gapping was not demonstrated within the recommended 75 pitch count limit in 10-year-olds, a relative decrease in glycogen stores of the flexor-pronator mass did occur, as well as a decrease in grip strength, with increasing subjective fatigue.
This study provides a foundation for further objective testing of physiologic changes that occur with pitching to better guide pitch count limits and improve the safety of young athletes.
尽管实施了投球数限制，但青少年投手的尺侧副韧带（UCL）损伤仍然令人担忧。屈肌-旋前圆肌团疲劳会导致动态稳定性下降，从而增加UCL上的压力。
目的/假设：通过评估内侧肘关节松弛度的变化来评估屈肌-旋前圆肌团的疲劳；无创性地描述肌肉糖原的变化；并确定随着青少年投手投球数增加至推荐的75球限制，主观疲劳、力量、活动范围（ROM）、投球速度和准确性的变化。假设随着投球数增加，内侧肘关节松弛度会增加，屈肌-旋前圆肌团的糖原含量会减少。
描述性实验室研究。
10岁的健康男性投手（n = 22）进行3组每组25次投球，组间间隔12分钟（3个时间点）。通过施加标准化外翻力并利用超声成像测量双侧尺肱关节间隙。使用超声软件测量双侧桡侧腕屈肌（FCR）以及指浅屈肌/尺侧腕屈肌（FDS/FCU）肌肉中肌肉糖原的相对变化，并记录为燃料百分位数。获得的其他测量指标包括主观疲劳、力量、ROM、速度和准确性。
投球手臂与非投球手臂之间或各时间点之间，内侧肘关节间隙没有差异。投球手臂的FCR燃料百分位数从基线到75次投球后显著下降（P = .05）。FDS/FCU燃料百分位数在各时间点之间没有差异。与基线相比，所有时间点双臂的疲劳测量值均显著更高（P≤.03）。75次投球后优势手臂的握力与25次投球后相比显著降低（P = .02）。
尽管在10岁儿童推荐的75球投球数限制内未显示内侧肘关节间隙增加，但随着主观疲劳增加，屈肌-旋前圆肌团的糖原储备确实相对减少，握力也下降。
本研究为进一步客观测试投球时发生的生理变化提供了基础，以更好地指导投球数限制并提高年轻运动员的安全性。
