Reliability and Concordance of 15-metre (15-m) Sprint Performance on Sand and Firm Surfaces

Within-Session and Between-Day Reliability of the 15-metre (15-m) Sprint on Sand and Firm Surfaces, and Concordance Between Conditions, in Male Beach-Sport Athletes

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.