**5. Conclusions**

A six-week core-training program along with regular swimming training significantly improved the freestyle swimming performance and core muscle properties, such as contractility (contraction time), excitability, extensibility, and elasticity, of the experimental group compared with the group that did not undergo the core-training program. These results can serve as evidence to assist coaches, trainers, and therapists in improving the swimming performance of young swimmers.

**Author Contributions:** A.K. and S.N. made substantial contributions to the concept, design, and study preparation. R.J., T.S.A. and Q.M. reviewed and edited the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board of Imam Abdulrahman Bin Faisal University (IRB-PGS-2019-03-241).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data that support the findings of this study are available from the corresponding author upon request.

**Acknowledgments:** Special thanks to the staff of the public authority for the sport swimming pool in Dammam for helping us throughout the data collection and giving us all the resources that we needed. The funding for this article was supported by each author from their own sources, to design the study and apply the training program. We also thank the Saudi Ministry of Health and Imam Abdulrahman Bin Faisal University, which allowed us to use their equipment for research and supported us throughout the research.

**Conflicts of Interest:** The authors declare no conflict of interest.
