Validez, confiabilidad y percentiles de un cuestionario que mide los niveles de actividad en adolescentes que viven a moderada altitud del Perú

The evaluation and monitoring of physical activity (PA) levels must be carried out constantly. The objectives of the study were a) To verify the validity and reliability of a questionnaire that measures the level of PA and b) to establish percentiles to classify PA levels of schoolchildren by age and gender. A descriptive cross-sectional study was carried out in 6 public establishments in the Province of Arequipa, Peru. A total of 1,339 adolescents (661 boys and 678 girls) were surveyed. A questionnaire comprising 11 items was used to measure PA. Validation was carried out using confirmatory factor analysis, whereas reliability was assessed by means of internal consistency. Percentiles were established. The average age of boys was 15.24 ± 1.82 years old, whilst girls were 15.39 ± 1.64 years old. Saturations ranged from 0.30 to 0.55. KMO adequacy measure was 0.83 (X2 = 2206.1, df = 55, p <0.000). The variance explanation % for the type of PA was 30.0%, for PA frequency 10.7%, for PA duration 9.0%, and for PA intensity 7.9%. Cronbach's Alpha was r = 0.71. Percentiles were proposed for each age and gender range. The proposed cut points were: Low (<p15), moderate (p15-p85) and high level of PA (> p85). The used PA questionnaire is valid and reliable; in addition, the developed percentiles are a useful tool to diagnose, classify, and monitor PA levels of adolescents who live at moderate altitudes in Peru.