A Systematic Review of the Influence of High-Intensity Interval Training on Body Composition and Synthesizing Evidence from Scientific Literature

Abstract

INTRODUCTION AND OBJECTIVE
 High-intensity interval training (HIIT) involves performing a series of intense exercises interspersed with periods of passive or active rest. HIIT provides changes in body composition and physical fitness. The aim of this study is to determine the impact of HIIT on changes in body composition and compare the results of HIIT with moderate-intensity continuous training (MICT) and resistance training (RT).
 REVIEW METHODS
 The PubMed and Google Scholar databases were searched for studies examining the impact of HIIT on changes in body composition. Articles published up to 31.03.2023 were included, with a particular focus on the most recent publications.
 STATE OF KNOWLEDGE
 The classification of HIIT considers the intensity, duration and number of bouts during training session, as well as the length of the intervention period. Body composition describes qualitive and quantitative elements in the human body. Improving body composition benefits health and enables better training results. HIIT promotes weight loss, reduces BMI and decreases the content of adipose tissue, including visceral fat. HIIT is equally or more effective than MICT in burning fat tissue. Resistance exercises added to HIIT protocols have a favorable effect on changes in body composition.
 SUMMARY
 The assessment of HIIT effects on changes in body composition is complicated due to various interpretations of its definition. Further analyses are needed to systematize knowledge of the benefits of different HIIT protocols. Research optimizing them for reducing adipose tissue based on age, gender, body mass and presence of metabolic disorders are necessary.