[Reliability and Validity of the Perceived Physical Fitness Scale questionnaire in Spanish students.]

Objective: Self-perception questionnaires are considered a useful alternative to assess the level of physical fitness (PF) of a specific population. However, very few questionnaires of this type have been validated in the Spanish population. The aim of this study was to identify the reliability and validity of the Perceived Physical Fitness Scale (PPFS) in Spanish students.

Methods: After a back-translation process, the PPFS questionnaire was administered twice to 722 students (primary school, n=207; secondary school, n=515) to determine its reliability. To identify its convergent validity, the International Fitness Scale (IFIS) was administered, as well as a set of PF field-based tests from the Eurofit battery. The questionnaire internal consistency, reliability and convergent validity of the questionnaire were assessed by means of the Cronbach's alpha, intraclass correlation coefficient and Pearson corelation coefficient.

Results: The internal consistency of the PPFS was accurate among Primary (α=0.702) and good among Secondary (α=0.888) students., Reliability was poor among Primary (ICC=0.490; 95% CI [0.298-0.665]) and good among Secondary (ICC=0.797; 95% CI [0.760-0.829]) students. The PPFS showed significant associations with PF levels assessed by means of the Eurofit (Primary; r=0.421; p<0.001 / Secondary; r=0.533; p<0.001) and with the IFIS scale (Primary; r=0.356; p<0.001 / Secondary r=0.792; p<0.001).

Conclusions: The Spanish adapted version of the PPFS questionnaire shows good reliability and acceptable convergent validity when used as a tool to assess PF among secondary school students. Its poor reliability, together with the weak association demonstrated against the IFIS scale among primary school students discourages the PPFS use at this educational level.