Acute effects of baseball movements on lumbar intervertebral discs and their associations with lumbar lordosis and anterior pelvic tilt

Abstract

This repeated-measures study investigated the acute effects of baseball movements on T2 and apparent diffusion coefficient (ADC) values of the lumbar intervertebral discs (LIVDs) and their associations with static lumbar lordosis and anterior pelvic tilt angles. Sixteen baseball or softball players (twelve men and four women) participated over four days. Participants performed pitching, batting, and ground-ball catching on separate days. Magnetic resonance imaging before and after each baseball movement assessed T2 and ADC values. Lumbar lordosis and anterior pelvic tilt angles during maximum anterior pelvic tilt while standing and squatting were measured on another day. Two-way ANOVA demonstrated no significant interactions or main effects of baseball movements or lumbar levels on percentage changes in T2 or ADC values. While T2 values did not change significantly after baseball movements, ADC values increased following pitching and ground-ball catching. Positive correlations were observed between specific disc-level changes and lumbar lordosis or anterior pelvic tilt angles. These findings suggest that limited static lumbar lordosis and anterior pelvic tilt may be associated with differences in acute diffusion responses within the LIVD during repetitive pitching and ground-ball catching movements. Given the exploratory nature of the analyses, these associations should be interpreted cautiously. J. Med. Invest. 73 : 398-409, August, 2026