Author(s): PARK, J., KIM, D., LEE, E., HWANG, J., KANG, N., HWANG, M. , Institution: INCHEON NATIONAL UNIVERSITY, Country: KOREA, SOUTH, Abstract-ID: 1082

INTRODUCTION:
Regular aerobic exercise plays a pivotal role in improving cardiorespiratory fitness (CRF) and preventing cardiovascular morbidity and mortality. Despite the clear health benefit of regular aerobic exercise of 150 minutes or more per week, many adults do not perform recommended amount of aerobic exercise due to time constraints. Recently, reduced-exertion high-intensity interval training (ReHIT) has been proposed as a time-efficient alternative. The effects of ReHIT on CRF remain inconclusive due to the limited number of studies with small sample sizes conducted to date. Without comprehensive analyses, it is difficult to determine the effects of ReHIT on CRF and cardiovascular disease (CVD) risk factors, and the minimum required amount of exercise. Therefore, the aim of this meta-analysis was to evaluate the effects of ReHIT on changes in CRF, a CVD risk factor, in sedentary adults.
METHODS:
The literature search was performed using two electronic databases including the PubMed and Web of Science from Oct 10 2024 to Dec 5 2024. We included the studies that focus on:
(a) sedentary adults, (b) ReHIT, (c) comparison with control (CONT) group or moderate-intensity continuous training (MICT) group, (d) CRF, and (e) randomized controlled trials (RCT).
The criteria for ReHIT were as follows:
(a) total duration of session: ≤10 minutes, (b) mode of exercise: Cycling, (c) minimum period ≥ 4 weeks.
RESULTS:
Total eight studies were included in this meta-analysis. The random effects meta-analysis revealed that ReHIT group demonstrated significantly higher VO2peak, a marker of cardiorespiratory fitness, than untrained CONT group (effects size = 0.972; 95% CI= 0.185-1.759, p = 0.015; I2 =74%). However, there was no significant difference in VO2peak in comparison with MICT group (effect size = 0.110; 95% CI = -0.518 to 0.737, p = 0.731; I2 = 61%). Additionally, there were no significant effects on body weight reduction in either CONT (effects size = -0.525; 95% CI= -1.387-0.337, p = 0.337; I2 =79%) or MICT group (effects size = -0.237; 95% CI= -0.915-0.441, p = 0.493; I2 =65%).
CONCLUSION:
The findings of this meta-analysis indicates that ReHIT can be an effective alternative for the typical moderate-intensity aerobic exercise with 150 minutes or more per week for improving CRF and reducing CVD risk in habitually sedentary adults. However, it seems difficult to expect additional health benefits through weight loss since the absolute amount of exercise in ReHIT is relatively low.