Analysis of baseball pitching and the risk of elbow injury

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H04007
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 59020:Sports sciences-related
• Research Institution: Waseda University
• Principal Investigator: Yanai Toshimasa 早稲田大学, スポーツ科学学術院, 教授 (50387619)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 肘外反ストレス / 野球 / 投手 / 投球動作 / バイオフィードバック

Outline of Final Research Achievements

All participants were able to reduce valgus stress, but only 29% were able to reduce elbow joint stress by >10 Nm when pitching fastballs at the same velocity. These pitchers successfully accomplished the two tasks (reducing elbow valgus stress while pitching fastballs at the same velocity) by altering the sequential motion of the kinetic chain. Specifically, they (a) tilted the scapula of the pitching limb posteriorly to a larger extent during the cocking phase, (b) reduced the sequentially achieved maximum angular velocities of the scapula, upper arm, and forearm, and (c) reduced the maximum elbow flexion torque and maximum shoulder horizontal adduction torque during the acceleration phase. These results indicate that although elbow valgus stress can be reduced by altering the pitching mechanics, motor learning of an effective pitching mechanics is not easily accomplished.

Free Research Field

スポーツ科学

Academic Significance and Societal Importance of the Research Achievements

肘関節ストレスという自己認識できない生体情報をリアルタイムでフィードバックすることによる運動学習効果を運動連鎖の協調的変化として提示できたことに学術的意義がある。さらに、球速を維持しつつ肘関節ストレスを大幅に低下させ得る投球メカニクスの特徴を、外傷障害の有無や個人差を排除した被験者内変動として抽出できたことは、投球メカニクスと肘関節ストレスを直接関連付け、運動力学的な因果関係を導き出すことを可能にする点で大きな意義がある。一方、球速維持と肘関節ストレス低下を両立させ得た投手が全体の約3割にとどまったことは、これらを両立させる投球フォームを学習する方法をさらに発展させる必要性を示すものとなった。