The sit and reach tests are probably the most common measurement tools for estimating hamstring flexibility in the sport setting. However, there is little scientific evidence on whether sit and reach tests are accurate tools. The purpose of this study was to determine the absolute reliability of the modified sit and reach (MSR) and back-saver sit and reach test (BSSR) for estimating hamstring flexibility in futsal (5-a-side indoor football) players.

A total of 30 participants completed 4 hamstring flexibility measurement sessions using MSR and BSSR with a two-week interval between consecutive sessions. Absolute reliability was examined using typical measurement error (TE), coefficient of variation (CV) and intraclass correlation coefficient (ICC). In addition, the 68% and 95% reference intervals associated with what might be considered a real change in hamstring flexibility were established for each measurement test.

High reliability measures were found for BSSR (TE=1.50cm; CV=3.47%; ICC=0.97) in contrast with the values observed for MSR (TE=3.54cm; CV=10.25%; ICC=0.84).

BSSR reported acceptable absolute reliability measures. Absolute reliability of MSR is still questionable. An observed change greater than 6.94% of baseline hamstring flexibility scores after performing a treatment would indicate that a real improvement on hamstring flexibility was likely if BSSR were performed.