School-Based High-Intensity Interval Training (HIIt) Programs for Promoting Physical Activity and Fitness in Children and Adolescents: A Systematic Review

Background: HIIT is a powerful stimulus in improving body composition and cardiometabolic risk in adults, and preliminary data in adolescents are also promising. HIIT is presented as a time-efficient alternative. Objectives: evaluate the utility of a HIIT program integrated in Physical Education (PE) classes on Physical Condition, PA and Motivation. Sources: Search through PubMed, MEDLINE, SPORTDiscus, CINAHL, MEDICLATINA, COCHRANE and Web of Science, was carried out during March 2019, considering studies since 2008. Eligibility criteria: (i) adolescents aged 10-19 years (ii) HIIT program applied in school (iii) outcomes on physical condition, PA and motivation (iv) intervention at least 4 weeks (v) RCT. Results: of the 5872 studies found a total of 14 studies were included. All works present significant improvements in, at least, 2 of the dimensions evaluated: physical condition and PA. There does not seem to be any great advantage in protocols that last in total more than 10min/session. Improvements in body composition registered, at most, a moderate Effect Size. HIIT is presented as a powerful stimulus in improving physical fitness, mainly on CRF in most protocols, and in power and speed when modality is plyometries. Improvements in PA had a moderate and large Effect Size.