This observational repeated-measures methodological study evaluated the reliability and agreement of a 15-m linear sprint test performed on sand and firm surfaces in male beach-sport athletes. Participants completed three maximal sprint attempts on each surface during up to two testing sessions conducted on separate days.

The study examined trial-to-trial reliability within each session, stability between testing days, and concordance between sprint times obtained on sand and firm surfaces. No therapeutic or training intervention was administered. Sand and firm surfaces were used exclusively as assessment conditions.

Male athletes participating in beach soccer, beach volleyball, or beach handball completed three maximal 15-m linear sprint attempts on both sand and firm surfaces. Each attempt was performed from a standardised standing start, with at least two minutes of passive recovery between attempts.

Testing comprised up to two sessions per participant on separate days. The order of the surface conditions was counterbalanced to reduce potential order and fatigue effects. Participants who attended two sessions completed the surfaces in the opposite order during the second session.

The primary measured variable was 15-m sprint time in seconds. The arithmetic mean of the three attempts and the fastest individual attempt were calculated for each surface and session. Within-session and between-day reliability were evaluated using intraclass correlation coefficients, coefficients of variation, standard errors of measurement, typical errors, and minimal detectable changes. Agreement between sand and firm-surface measurements was assessed using Lin's concordance correlation coefficient and Bland-Altman analysis.

Inclusion Criteria

• Male athlete participating in beach soccer, beach volleyball, or beach handball.
• Minimum of six months of regular beach-sport training.
• Able to complete maximal 15-m sprint assessments on sand and firm surfaces.
• Provision of written informed consent before participation.

Exclusion Criteria

• Musculoskeletal injury during the six weeks preceding testing.
• Acute illness during the seven days preceding testing.
• Failure to complete at least one full testing session.

The study population consisted of male athletes participating in beach soccer, beach volleyball, or beach handball in Antioquia, Colombia. Participants were recruited using convenience sampling based on their availability during the data-collection period. Eligible athletes had completed at least six months of regular beach-sport training. Athletes with a musculoskeletal injury during the preceding six weeks, an acute illness during the preceding seven days, or who were unable to complete at least one full testing session were excluded.

De-identified individual participant data underlying the results reported in the publication may be shared upon reasonable request. Requests will be evaluated by the principal investigator and the responsible institution, considering the scientific purpose of the proposed use, participant confidentiality, ethical requirements, and compliance with applicable data-protection regulations. Data will be provided only after approval of the request and completion of an appropriate data-use agreement.

Data may be made available beginning after publication of the primary study results and will remain available for five years.

Researchers who submit a methodologically sound proposal may request access to the de-identified data. Requests must describe the research objectives, planned analyses, data-security procedures, and intended outputs. Access will be subject to approval by the principal investigator and the responsible institution, as well as completion of a data-use agreement.