Within-subject time series angular velocity differences between in-game high and low velocity fastballs in college baseball pitchers.

PURPOSE: The purpose of the current study is to investigate the within-pitcher differences in time series angular velocities of the pelvis, trunk, shoulder, and elbow for high and low velocity fastballs in college baseball pitchers.

METHODS

In-game data were retrospectively analyzed from 82 NCAA Division 1 pitchers ([1.89 ​± ​0.06] m, [92.8 ​± ​9.5] kg). Kinematic data were collected using an in-game markerless motion capture system. Time series data of pelvis, trunk, shoulder, and elbow angular velocities for each pitcher's fastest and slowest fastball were extracted for the pitch cycle (foot contact to ball release) and used for analysis. Within-subject time series comparisons were conducted using statistical parametric mapping (SPM) paired samples t-tests (α ​= ​0.012 5).

RESULTS

Each of the tested segments were significantly faster in the fastest fastball trial compared to the slowest fastball trial. The duration of significance in reference to the pitch cycle, test statistic, and p-value, for each segment are as follows: Pelvis: 0%-4%, t ​= ​3.54, p ​= ​0.012; Trunk: 30%-67%, t ​= ​5.62, p ​< ​0.001; Shoulder External Rotation: 3%-50%, t ​= ​-6.03, p ​< ​0.001; Shoulder Internal Rotation: 96%-100%, t ​= ​4.11, p ​= ​0.008; Elbow: 75%-86%, t ​= ​4.13, p ​< ​0.001.

DISCUSSION: Within-subjects differences exist in time series angular velocities when comparing the fastest and slowest fastball. These time series differences provide additional information to distinguish fastball velocity beyond what discrete metrics can provide. Pitchers should look to rotate each segment faster, and optimize the sequencing of these movements, to increase pitch velocity.