Author(s): POON, E.T.C., LI, J., LITTLE, J., WONG, S., HO, R., Institution: THE CHINESE UNIVERSITY OF HONG KONG, Country: HONG KONG, Abstract-ID: 1671

INTRODUCTION:
This study aimed to synthesize the available evidence on the efficacy of interval training compared to moderate-intensity continuous training (MICT) and non-exercise control (CON) in reducing body adiposity in adults.
METHODS:
An umbrella review with meta-analysis was performed. A systematic search was conducted in seven databases (MEDLINE, EMBASE, Cochrane Database, CINAHL, Scopus, SPORTDiscus, and Web of Science) until October 2023. Systematic reviews with meta-analyses of randomised controlled trials (RCTs) comparing interval training and MICT/CON were included. Literature selection, data extraction, and methodological quality assessment (AMSTAR-2) were conducted independently by two reviewers. Meta-analyses were performed using a random-effects model. Sub-group analyses were conducted based on the type of interval training (high-intensity interval training [HIIT] and sprint interval training [SIT]), intervention duration (<12 weeks or ≥ 12 weeks) and body mass index (normal range or overweight/obesity).
RESULTS:
Sixteen systematic reviews, including 78 RCTs and 2,447 unique participants, met the inclusion criteria. Most systematic reviews had a critically low (n=6) or low (n=6) AMSTAR-2 score. Interval training demonstrated significantly greater reductions in total body fat % (BF %) compared with MICT (weighted mean difference [WMD] = -0.72; 95% confidence interval [CI] =-1.14 to -0.29) and CON (WMD = -1.50; 95% CI = -2.40 to -0.60). Significant reductions in fat mass, visceral adipose tissue, subcutaneous abdominal fat, and android abdominal fat were also observed following interval training compared to CON. Sub-group analyses indicated that both HIIT and SIT resulted in superior BF% loss than MICT, with greater benefits observed in individuals with overweight/obesity and with longer duration interventions (i.e., ≥ 12 weeks).
CONCLUSION:
This novel umbrella review with large-scale meta-analysis provides an updated synthesis of evidence with implications for physical activity guideline recommendation. The findings support interval training as a viable exercise strategy for reducing adiposity in the general population.