Potentiated physical education interventions are effective in ameliorating physical fitness of Italian primary schoolchildren

School-based PE programs are poor nationwide and they need to be potentiated against a rising prevalence of chronic diseases and physical inactivity. Our aim was to evaluate the effectiveness of 40 versus 20 physical education (PE) classes on physical fitness of a cohort of northwestern Italian primary schoolchildren. Methods: 5751 schoolchildren aged 6–11years were studied between November 2017 and May 2018 from 25 primary schools of Lombardy. Pupils underwent either a control group (CON, # = 2553; $ = 2864) or an experimental group (PLUS, # = 158; $ = 176) in which they attended 20 or 40 PE classes, respectively. Sixty-minute classes were delivered once a week (CON) or biweekly (PLUS) by qualified PE teaching assistants through an approximate school semester. Anthropometrics, cardiorespiratory (six-minute walking test, 6MWT), musculoskeletal (standing broad jump, SBJ) and motor fitness (4 9 10 m shuttle run test, SRT) were evaluated at baseline and upon completion of the study. Wilcoxon matched-pairs signed rank test was performed. Results: At the end of the study, PLUS group revealed a better dis- tribution of BMI categories (under weight UW Dpost–pre = - 5.4%; normal weight NW Dpost–pre = ? 8.9%; overweight OW Dpost–pre = - 3.6%) compared to controls (UW Dpost–pre = - 0.4%; NW Dpost– pre = ? 1.6%; OW Dpost–pre = - 1%). PLUS children improved almost all fitness performances by a greater extent (6MWT: pre 606.8 ± 104/post 644.5 ± 93.5 m, p \ 0.0001; SBJ: pre 119.1 ± 25.3/post 124.8 ± 25.9 cm, p \ 0.0001; SRT: pre 14.9 ± 2.5/post 13.8 ± 1.9 s, p \ 0.0001) with respect to CON children (6MWT: pre 611.4 ± 102.1/post 623.6 ± 92.4 m, p \ 0.0001; SBJ: pre 116.8 ± 25.3/post 123.4 ± 24 cm, p \ 0.02; SRT: pre 14.8 ± 2.4/post 14.3 ± 2 s, p \ 0.0001). Means and SD. Conclusions: This design confirms the need to implement well- structured, school-based PE programs. Particularly, higher frequency of PE classes is advocated in order to ameliorate health-related physical fitness c