Immediate changes and recovery of supraspinatus, long head biceps and shoulder range of motion after pitching in youth baseball players: How long is the rest needed after pitching?

Abstract

Introduction: Baseball players usually get injuries such as rotator cuff tear, SLAP lesion due to repetitive pitching since youth. However, there have been few researches regarding effects of pitching on shoulder muscles and time-based recovery of youth baseball players. The purpose of this study was to evaluate the effect of pitching on supraspinatus muscle-tendon, long head biceps tendon (LHBT) and shoulder ROM, and time-based recovery of youth baseball players using sonoelastography.

Material and Methods: Fifteen youth baseball players (mean age: 12.1 ± 3.5 yrs) were enrolled at a single institute. The thickness of supraspinatus tendon and LHBT and the strain ratios (SR) of supraspinatus muscle and tendon were measured using sonoelastography, and ROM of shoulder joint (abduction, external rotation (ER) at 90° abduction (ABER), internal rotation (IR) at 90° abduction (ABIR), horizontal adduction (HA) were measured by a bubble goniometer. Every measurement was performed on throwing shoulders before and immediate period after pitching (mean pitch count (n)

78.3 ± 13.3), 30 minutes, 24 hours, and 72 hours after pitching.

Results: At the immediate measurement after pitching, the thickness of supraspinatus tendon (before pitching, 6.64 mm

after pitching, 6.27 mm, p = 0.026), and LHBT (before pitching, 2.56 mm

after pitching

2.26 mm, p = 0.02) were significantly decreased. Those decreases of thickness of two tendons were recovered at 72 hours after pitching. The SR of supraspinatus muscle was tend to be decreased, and the SR of supraspinatus tendon tend to be increased at the immediate period after pitching, but recovered at 72 hours after-pitching. For shoulder ROM, ABER was increased (119.7° to 127.3°, p = 0.001) and HA was decreased (34.7° to 29.3°, p = 0.02) at the immediate measurement after-pitching. Those ROMs were recovered at 72 hours (ABER

p = 0.017, HA

p = 0.04).

Conclusion: The immediate effect of pitching on supraspinatus muscle-tendon, LHBT, and shoulder ROM of youth baseball players was confirmed through the current data. These changes were recovered to pre-pitch level at 72 hours after pitching. Therefore, it is recommended to take enough rest until third day after pitching to prevent injuries of youth baseball players.