The main purpose of this study is to analyse the effect of a multicomponent intervention, applied during one scholar semester, on body composition, strength, flexibility, cardiorespiratory fitness, lipid and metabolic profile, and body image of students from sixth to ninth grade. This is a non-randomized controlled design. Approximately 568 schoolchildren of grades sixth through ninth were recruited from 2 public secondary schools in Florianópolis, Brazil. The main component of the intervention entitled "MEXA-SE" (move yourself) consisted of the implementation of three physical education classes per week with aerobic exercises, strength and flexibility activities. In addition, play activities in school recess, and educational activities on physical activity, sedentary behaviour, eating habits and body image were performed. Data collection was performed before and immediately after 14 weeks of intervention. The primary outcomes included the body composition, strength, flexibility, cardiorespiratory fitness, lipid and metabolic profile, and body image. Other variables included were: physical activity level, sedentary behaviour, and blood pressure level. Other components of the lifestyle (e.g., eating habits), psychological (e.g., self-rated health) also were evaluated in the participants. Descriptive analysis, two-way ANOVA for mixed models and ANCOVA will be applied for within and between comparison groups, if the premises of this test are met. The level of significance for the study was 5% for two-tailed tests.