2025, Vol. 29 ›› Issue (8): 1727-1740

Effects of interval and continuous training on the quality of life in physically inactive adults: a meta-analysis

Zheng Huakun1, Yin Mingyue2, Liu Qian1   

Abstract: OBJECTIVE: High-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) can improve the quality of life of patients with clinical chronic diseases, but their application effects and regulatory factors in adults with insufficient physical activity are still unclear. This study aimed to explore the application effects and regulatory factors of HIIT and MICT on the quality of life of adults with insufficient physical activity.
METHODS: A systematic literature search was conducted in databases including Web of Science Core Collection, Medline (EBSCO Host), PubMed, and Cochrane Library. The search time limit was from the establishment of each database to September 2023. The types of included literature were randomized controlled trials, and the research subjects were physically inactive adults. RevMan 5.4 software and the GRADE evidence evaluation framework were used to assess the quality of the included literature. Main effects pooling of random effects models was performed using R Studio (version 4.2.0). Subgroup analyses, regression analyses, and sensitivity analyzes were used to explore the sources of study heterogeneity and moderators.
RESULTS: (1) Thirty-two randomized controlled trials of moderate to high quality were included, involving 2 083 physically inactive adults (HIIT group n=474; MICT group n=708; control group n=901). (2) Compared with the non-training control group, HIIT [Hedges’ g=0.61; 95% confidence interval (CI): 0.40-0.83; I2=45%] and MICT (Hedges’ g=0.66; 95% CI: 0.25-1.08; I2=89%) significantly improved the quality of life. Direct comparison studies of HIIT and MICT found no significant differences in the quality of life (Hedges’ g=-0.01; 95% CI: -0.23-0.21; I2=0%). (3) Subgroup analysis showed that HIIT and MICT were more effective in improving the physical components of the quality of life (HIIT: Hedges’ g=0.82 vs. 0.75; MICT: Hedges’ g=0.74 vs. 0.55), while cycling had a better trend in improving overall quality of life (HIIT: Hedges’ g=0.74 vs. 0.36; MICT: Hedges’ g=1.08 vs. 0.52). (4) Additionally, regression analysis did not identify any significant moderators (P > 0.05 for all factors). (5) None of the above meta-analyses found publication bias (Egger test P > 0.05).
CONCLUSION: (1) Moderate to high level evidence shows that both HIIT and MICT can improve the quality of life of adults with insufficient physical activity, and the intervention effects between the two are similar. Therefore, when choosing between these two options, it is necessary to comprehensively consider factors such as time economy, scheduling flexibility, and application feasibility to formulate a personalized exercise plan. (2) This study recommends that when applying HIIT, a low-volume protocol (for example, 5 groups each time, 1 minute each), 3 times/week, and ride at 80%-95% of the maximum heart rate is used to achieve the theoretical best improvement effect. (3) Although MICT improves the quality of life, there is insufficient evidence that increasing exercise duration brings additional benefits. Therefore, this study recommends that when MICT is conducted, it should be carried out more than three times a week, with each training duration controlled between 25 and 60 minutes, and cycling at 50%-75% of the maximum heart rate, in order to achieve the theoretically expected best improvement effect.
Key words: exercise intervention, high-intensity interval training, moderate-intensity continuous training, quality of life, meta-analysis, physical inactivity, physical and mental health, randomized controlled trial