Today, available time for physical activity has been continuously decreasing, whilst, school-time physical education (PE) classes appear to be the only real option for many adolescents to engage in physical activity and exercise. The aim of the present study was to investigate fitness and health related parameters over one academic year, and after the summer holidays for adolescents who do not engage in out-of-school physical activities. Participants were 153 students (age: 15-17 years; boys n = 86) who exercised only during PE (2 × 45-min periods per week). Body fat, flexibility, handgrip strength, squat jump, 30 m sprint and cardiorespiratory fitness were examined at the beginning and end of a school year, and after the ensuing summer holidays. The boys improved handgrip and flexibility, but no other significant improvement was observed over the school year in any of the examined physical fitness parameters, or obesity indices. Instead, the girls' cardiorespiratory fitness decreased over the summer holidays. It seems that exercising only twice a week during school PE classes is insufficient to induce significant improvements in physical fitness, body composition and health parameters.
Keywords: body fat; cardiorespiratory fitness; physical education; strength.