## 2 Materials and Methods
### Protocol  
Participants completed a Sociodemographic and Clinical Questionnaire to accurately characterize the sample and identify any possible exclusion criteria. The Sociodemographic and Clinical Questionnaire included: personal data (two items), training habits (one item), and clinical background (nine items). All data collection was performed prior to players' training. The necessary information regarding the procedures to be performed, as well as the clarification of any doubts that might arise, were provided to all participants. After completing the socio-demographic and clinical questionnaire, the players were randomly assigned to two designated groups, the Intervention Group (IG; n = 40) (dynamic cupping therapy) and the Control Group (CG; n = 40) (no intervention group), using GraphPad online tool ([[https://www.graphpad.com/quickcalcs](https://www.graphpad.com/quickcalcs)]([https://www.graphpad.com/quickcalcs](https://www.graphpad.com/quickcalcs)), accessed on 1 February 2024), which ensures unbiased allocation by generating a random sequence. This randomization process minimizes the risk of systematic bias in group assignments and enhances the validity of our findings. However, the use of a convenience sample consisting of 80 senior male handball players introduces potential limitations. The representativeness of this sample may be constrained, potentially affecting the generalizability of the results. The implications of this limitation are discussed further in the Section 4. First, anthropometric measurements were performed using a stadiometer (Seca(r) Medical Scales and Measuring Systems(r), Birmingham, UK) to record their height and a scale (Seca(r) Medical Scales and Measuring Systems(r), Birmingham, UK) to measure their weight. The following evaluation parameters were collected by a physiotherapist investigator. The average time to assess each participant was 20 min. Data were collected in two moments: initial moment (M0) and after the application of cupping for IG or after a resting period for CG (M1). The study was carried out on the dominant upper limb. To identify the dominant upper limb, a test was carried out in which a ball was thrown at the athlete and the athlete had to return the ball through a pass using the upper limb [26]. Then, the initial evaluation moment (M0) was performed, which consisted of goniometric evaluation of shoulder active range of motion (AROM). For each movement, the players were asked to perform the movement for the first time on the non-dominant side to understand the movement without making compensations. In goniometry assessment, a 30,48 cm plastic BASELINE(r) universal goniometer (Model 12-1000; Fabrication Enterprises, White Plains, NY, USA) was used for all goniometric measurements, following the methodology used by [PERSON] (1997) [27]. Participants were instructed to perform various active movements with the dominant upper limb. Assessments for shoulder flexion, extension, abduction, and adduction were conducted while the participants stood, with a focus on minimizing compensatory movements. For the assessment of abduction and horizontal adduction, participants remained seated on a Posturarte(r) Olympic massage table (Posturarte, Braga, Portugal). Internal and external rotation movements were also assessed while the participants were lying supine on the same type of table, ensuring no inclination. Any measurements were considered invalid if the participant compensated using another body part. Three measurements were taken for each movement, and the average of these three was used for analysis [27; 28]. In the investigation by [PERSON] and [PERSON] (2012) [29], the authors evaluated the reliability and concurrent validity of digital inclinometric and goniometric measurements of active shoulder flexion, abduction, and external and internal rotation.