Grip strength is not related to increased medial elbow joint-space gapping induced by repetitive pitching

Hiroshi Hattori; Kiyokazu Akasaka; Takahiro Otsudo; Toby Hall

doi:10.1016/j.jseint.2020.07.007

Grip strength is not related to increased medial elbow joint-space gapping induced by repetitive pitching

JSES Int. 2020 Aug 1;4(4):1026-1030. doi: 10.1016/j.jseint.2020.07.007. eCollection 2020 Dec.

Authors

Hiroshi Hattori^{1

2}, Kiyokazu Akasaka^{1

3}, Takahiro Otsudo^{1

3}, Toby Hall⁴

Affiliations

¹ Graduate School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan.
² Department of Rehabilitation, Kawagoe Clinic, Saitama Medical University, Kawagoe, Saitama, Japan.
³ School of Physical Therapy, Saitama Medical University, Moroyama, Saitama, Japan.
⁴ School of Physiotherapy and Exercise Science, Curtin University, Perth, WA, Australia.

Abstract

Background: Pitching induces elbow valgus stress, which can lead to an increase in medial elbow joint-space gapping when repeated. Previous basic research on the medial elbow joint shows that the contraction associated with gripping reduces medial elbow joint-space gapping. However, no studies have investigated the relationship between grip strength and increased medial elbow joint-space gapping during repetitive pitching. The purpose of this study was to investigate whether grip strength is related to medial elbow joint-space gapping during repetitive pitching. Our hypothesis was that increased grip strength would correlate with a reduction in medial elbow joint-space gapping.

Methods: A total of 25 high school baseball players participated in this study. Each subject pitched 100 times. The medial elbow joint-space gapping and grip strength were measured before and after pitching. Correlation analysis was used to identify the relationship between medial elbow joint-space gapping and grip strength.

Results: Medial elbow joint-space gapping (mm) increased by 25.5% ± 8.0% after 100 pitches (gapping before, 5.0 ± 0.9; gapping after, 6.2 ± 1.1; P < .001). Grip strength (kg) after 100 pitches decreased by 2.8% ± 7.4% to that before pitching (before, 40.4 ± 5.5; after 39.2 ± 5.6; P < .05). There was no significant correlation between the change rate of medial elbow joint gapping and grip strength at any time (grip strength: before pitching, P = .74; after pitching, P = .40; change rate from before to after pitching, P = .24).

Conclusions: Grip strength is not related to increased medial elbow joint-space gapping induced by repetitive pitching. This indicates that physical ability expressed by grip strength is not associated with preventing increases in medial elbow joint-space gapping during repetitive pitching. Further studies are required to investigate the stabilization mechanism of the medial elbow joint during pitching.

Keywords: Elbow; baseball; grip strength; medial elbow joint-space gapping; repetitive pitching; ultrasound.