Background Performance of high-intensity interval training (HIIT) by children and adolescents improves physical and health-related fitness, as well as cardiometabolic risk factors. Objectives To assess the impact of HIIT performed at school, i.e. both in connection with physical education (intra-PE) and extracurricular sports activities (extra-PE), on the physical fitness and health of children and adolescents. Methods PubMed and SPORTDiscus were searched systematically utilizing the following criteria for inclusion: (1) healthy children and adolescents (5–18 years old) of normal weight; (2) HIIT performed intra- and/or extra-PE for at least 5 days at an intensity ≥ 80% of maximal heart rate (HRmax) or peak oxygen uptake (VO2peak) or as Functional HIIT; (3) comparison with a control (HIIT versus alternative interventions); and (4) pre- and post-analysis of parameters related to physical fitness and health. The outcomes with HIIT and the control interventions were compared utilizing Hedges’ g effect size (ES) and associated 95% confidence intervals. Results Eleven studies involving 707 participants who performed intra-PE and 388 participants extra-PE HIIT were included. In comparison with the control interventions, intra-PE HIIT improved mean ES for neuromuscular and anaerobic performance (ES jump performance: 5.89 ± 5.67 (range 1.88–9.90); ES number of push-ups: 6.22 (range n.a.); ES number of sit-ups: 2.66 ± 2.02 (range 1.24–4.09)), as well as ES fasting glucose levels (− 2.68 (range n.a.)) more effectively, with large effect sizes. Extra-PE HIIT improved mean ES for neuromuscular and anaerobic performance (ES jump performance: 1.81 (range n.a.); ES number of sit-ups: 2.60 (range n.a.)) to an even greater extent, again with large effect sizes. Neither form of HIIT was more beneficial for parameters related to cardiorespiratory fitness than the control interventions. Conclusion Compared to other forms of exercise (e.g. low-to-moderate-intensity running or walking), both intra- and extra-PE HIIT result in greater improvements in neuromuscular and anaerobic performance, as well as in fasting levels of glucose in school children.

ZusammenfassungDas hochintensive Intervalltraining (HIIT) hat das Potenzial, bei Kindern und Jugendlichen die gesundheitsrelevante Fitness zu verbessern. Aus diesem Grund haben Studien HIIT im Sportunterricht oder in anderen Bereichen des Schulsettings, wie zum Beispiel im Klassenzimmer, eingesetzt.Das Ziel dieses Artikels ist, die Effektivität von HIIT-Interventionsstudien im Sportunterricht sowie im Schulkontext außerhalb des Sportunterrichts, bezogen auf die kardiovaskuläre Fitness von Kindern und Jugendlichen, mittels narrativer Überblicksarbeit darzustellen.Die Mehrzahl der Studien zeigen deutliche Verbesserungen der kardiovaskulären Fitness von Kindern und Jugendlichen nach den HIIT Interventionen im Sportunterricht sowie im Schulkontext außerhalb des Sportunterrichts.Das gute Verhältnis von Aufwand und Nutzen hinsichtlich gesundheitsrelevanter Fitness macht das hochintensive Intervalltraining zu einer geeigneten Trainingsform für die Verbesserung der gesundheitsrelevanten Fitness von Kindern und Jugendlichen im Schulsetting.