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.