Brief Summary We want to find out whether training with a weighted vest can help improve speed in U-14 baseball players. To do this, we will conduct a study with athletes like you, comparing performance before and after the training program.

How will we do it?

Participants will be randomly assigned to one of two groups:

Group 1: Will train with a weighted vest.

Group 2: Will train without a weighted vest.

Both groups will follow the same training program over 16 sessions. Running speed will be measured before and after the program to evaluate any improvements.

Who can participate?

Boys aged 13 to 14 years.

Members of the Tigres Baseball Club from San Pedro de Urabá.

Must have permission from a parent or legal guardian.

Who cannot participate?

Players with current injuries.

Those who regularly practice another sport.

Those who leave the club or are unable to complete the pre- and post-tests.

Is it safe? Yes! All procedures follow safety guidelines and will be conducted with informed consent from players and their families. Our goal is to enhance sports performance in a safe and effective way.

This randomized controlled trial aims to evaluate the effects of sprint training with and without a weighted vest on running speed in male U-14 baseball players. The intervention will consist of a standardized sprint training program performed over 16 sessions (2-3 sessions per week for approximately 6 weeks). Participants will be randomly assigned into two groups: an experimental group using weighted vests and a control group without weighted vests.

The weighted vest will represent approximately 10% of the participant's body weight and will be worn during specific sprint training exercises. Both groups will perform the same sprint-based training protocol, including linear sprints and acceleration drills, under the supervision of qualified coaches.

The primary outcome will be sprint performance, assessed via time over 20 meters (with or without intermediate splits, depending on equipment availability). Measurements will be taken at baseline and after completion of the training program.

Inclusion and exclusion criteria have been defined to ensure participant safety and homogeneity of the sample. Ethical approval has been obtained, and informed consent will be secured from parents or legal guardians before participation. This study intends to contribute to evidence-based strategies for improving speed in youth baseball players through load-based sprint training interventions.

Inclusion Criteria:

• Male athletes aged 13 to 14 years
• Member of the Tigres Baseball Club of San Pedro de Urabá
• Signed informed consent from parent or legal guardian
• Regular attendance at training sessions during the intervention period

Exclusion Criteria:

• Current musculoskeletal injury
• Regular participation in other sports or physical training programs
• Failure to complete pre- and post-intervention tests
• Withdrawal from the club during the study period

IPD will be shared upon reasonable request. De-identified data may be available to qualified researchers after publication of the main findings.

IPD and supporting documents will be available beginning 6 months after publication of the main findings and will remain available for up to 3 years.

De-identified individual participant data (IPD) will be available to qualified researchers upon reasonable request. Requests should include a brief research proposal and ethical approval (if applicable). Data will be shared via secure file transfer upon agreement with the principal investigator.