Kinematic Sequence Differences Between Trained Baseball Players and Untrained Adolescent Individuals

An overhead throwing motion is a common gross motor skill often taught in early childhood to improve physical activity participation. Yet, research investigating motor efficiency in overhead throws often focuses on improving performance in trained individuals. This project compares kinematic sequencing between trained and untrained youth. After a brief warm-up, untrained high school students (N = 9) and trained high school and college students (N = 10) threw a weighted tennis ball for accuracy (N = 10 throws). Upper extremity angular velocities were collected using 3-dimensional inertial sensor motion capture. Kinematic sequencing of joints and segments (pelvis, trunk, shoulder, elbow, and wrist) was assessed using Kruskal-Wallis test; Friedman and Wilcoxon tests identified group differences between sequences. Seven independent kinematic sequences were identified (N = 2 unique trained; N = 3 unique untrained; N = 2 shared). The rankings for the trained group maintained a mostly consistent pattern with only elbow and wrist joints producing similar rankings. The untrained group lacked that consistency with similar rankings of elbow versus wrist and shoulder versus elbow. Trained individuals threw with a more efficient proximal-to-distal sequencing pattern than the untrained participants, specifically at the trunk and shoulder. Continuous training of gross motor skills beyond initial skill development is necessary to maintain motor proficiency.