The goal of this quasi-experimental clinical trial is to evaluate whether weighted jump rope (WJR) training can improve the isokinetic shoulder strength profile in male and female CrossFit practitioners.

The main questions it aims to answer are:

• Does six weeks of WJR training affect internal and external shoulder rotational peak torque relative to body mass?
• Does WJR influence the external/internal shoulder rotation ratio in dominant and non-dominant arms at varying angular velocities? Researchers will compare pre- and post-intervention isokinetic measurements to see if WJR training leads to significant changes in shoulder strength and balance.

Participants will:

• Incorporate WJR sessions three times per week into their usual CrossFit training.
• Undergo isokinetic testing of both shoulders at baseline and post-intervention at 60°/s, 180°/s, and 300°/s.
• Have their training adherence and technique monitored throughout the study.

Model: Single Group

Model Description:

This study followed a single-arm, quasi-experimental pre-post design in which all participants underwent the same intervention: six weeks of weighted jump rope (WJR) training, integrated into their regular CrossFit routines. The intervention's impact on isokinetic shoulder strength variables was assessed by comparing pre- and post-intervention measures within the same group of participants.

Number of Arms

1, Only one group received the intervention-there was no control or comparator group.

Masking Outcomes Assessor.

Masking Description:

Due to the nature of the physical intervention (WJR training), blinding participants and care providers was not feasible. However, outcome assessors conducting the isokinetic tests were blinded to the study's hypotheses and group allocations to reduce measurement bias.

Allocation N/A. Participants were not randomly assigned but instead enrolled in a single group to undergo the same intervention protocol.

Enrollment 18 participants

Inclusion Criteria:

• self-reported CrossFit training experience. Accordingly, participants were classified into one of three categories (Torres-Banduc et al., 2021): advanced level (≥36 months of regular training, defined as ≥3 sessions of ≥120 minutes per week); intermediate level (12 to <36 months); and beginner level (6 to <12 months).
• no injuries in the three months preceding the study.

Exclusion Criteria:

• musculoskeletal issues impacting muscle strength or the ability to undergo isokinetic shoulder evaluation.
• self-reported use of anabolic steroids or other prohibited substances that might influence the study results.

Individual participant data will not be publicly shared, but may be made available upon reasonable request to the corresponding author. This approach ensures data privacy and confidentiality, while still allowing access for valid scientific purposes.