Effects of trunk stabilization using manual support on lower trapezius muscle strength in college baseball players

Yuki Nomura, Satoshi Ichikawa, Shu Asano, Keigo Okuyama, Kazuma Yamagata, Yoshinari Sakaki, Shun Watanabe, Hajime Toda, Masaki Katayose
Purpose:

This study aimed to compare LT muscle strength in college baseball players under two conditions: with trunk stabilization using manual support (LT-s) and without trunk stabilization (LT-ns). Additionally, we aimed to investigate the relationship between shoulder rotational muscle strength and LT muscle strength, with or without trunk stabilization.

Methods:

Twenty-five male college baseball players with no upper-body symptoms participated in this study. Isometric muscle strength values for LT-ns, LT-s, shoulder internal rotation (IR), shoulder external rotation in the neutral position (ER), and shoulder external rotation at end range (ER-e) were measured using handheld dynamometry. For each participant, the average muscle strength across two trials was used as the representative value.

Results:

The shoulder strength measurements for the throwing arm were as follows: 2.6 N/kg for LT-ns, 2.8 N/kg for LT-s, 2.3 N/kg for IR, 2.1 N/kg for ER, and 1.6 N/kg for ER-e. LT-s was significantly higher than LT-ns (p 0.01). LT-s showed significant correlations with IR (r = 0.55, p 0.01), ER (r = 0.59, p 0.01), and ER-e (r = 0.79, p 0.01). LT-ns also demonstrated significant correlations with IR (r=0.47, p0.05), ER (r=0.58, p0.01), and ER-e (r=0.68, p0.01).

Conclusion(s):

These findings suggest that LT muscle strength increases when trunk stabilization is applied. Additionally, baseball players with higher LT muscle strength tend to have greater shoulder rotational strength, regardless of trunk stabilization. These findings suggest that LT muscle strength increases when trunk stabilization is applied. Additionally, baseball players with higher LT muscle strength tend to have greater shoulder rotational strength, regardless of trunk stabilization.

Implications:

For baseball players who show improved LT muscle strength with trunk stabilization, a training program that emphasizes trunk stability could be advantageous. Conversely, for players whose LT strength remains unchanged with trunk stabilization, a program focusing specifically on the LT muscle might be more beneficial. Implementing these targeted training programs may result in more effective conditioning strategies aimed at preventing shoulder injuries.

Funding acknowledgements:
No funding was received to assist with the preparation of this study.
Keywords:
Scapular stability
Trunk stability
Baseball pitching
Primary topic:
Sport and sports injuries
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
Sapporo Medical University Ethical Committee
Provide the ethics approval number:
30-2-52
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

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