Effects of High-Intensity Interval Training on Body Composition and Cardiometabolic Health in Physically Inactive Individuals: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Figures

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  Figure 1. PRISMA flow diagram of the study selection process.

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  Figure 2. Conservative study-level summary of outcome-specific RoB 2 judgments. The studies presented in the figure correspond, from top to bottom, to references [23,24,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50]. Green, yellow, and red indicate low risk of bias, some concerns, and high risk of bias, respectively. D1–D5 represent the five RoB 2 domains: bias arising from the randomization process, bias due to deviations from intended interventions, bias due to missing outcome data, bias in measurement of the outcome, and bias in selection of the reported result.

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  Figure 3. Distribution of conservative study-level risk-of-bias judgments across the five RoB 2 domains. Outcome-specific assessments were summarized at the study level using the more conservative judgment when judgments differed across outcomes. The proportions of the 24 studies judged as low risk, some concerns, or high risk of bias are presented for each domain. Green, yellow, and red indicate low risk of bias, some concerns, and high risk of bias, respectively.

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  Figure 4. Forest plots of weighted mean differences for (a,b) body weight and (c,d) body mass index. (a,c) HIIT vs. CON; (b,d) HIIT vs. MICT. CON, non-exercise control; HIIT, high-intensity interval training; MICT, moderate-intensity continuous training. Green squares indicate individual study estimates, with their size reflecting study weights; black diamonds indicate pooled estimates with 95% confidence intervals.

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  Figure 5. Forest plots of weighted mean differences for (a,b) body fat percentage and (c,d) waist-to-hip ratio. (a,c) HIIT vs. CON; (b,d) HIIT vs. MICT. CON, non-exercise control; HIIT, high-intensity interval training; MICT, moderate-intensity continuous training. Green squares indicate individual study estimates, with their size reflecting study weights; black diamonds indicate pooled estimates with 95% confidence intervals.

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  Figure 6. Forest plots of weighted mean differences for (a,b) systolic blood pressure and (c,d) diastolic blood pressure. (a,c) HIIT vs. CON; (b,d) HIIT vs. MICT. CON, non-exercise control; HIIT, high-intensity interval training; MICT, moderate-intensity continuous training. Green squares indicate individual study estimates, with their size reflecting study weights; black diamonds indicate pooled estimates with 95% confidence intervals.

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  Figure 7. Forest plots of weighted mean differences for (a,b) high-density lipoprotein cholesterol and (c,d) low-density lipoprotein cholesterol. (a,c) HIIT vs. CON; (b,d) HIIT vs. MICT. CON, non-exercise control; HIIT, high-intensity interval training; MICT, moderate-intensity continuous training. Green squares indicate individual study estimates, with their size reflecting study weights; black diamonds indicate pooled estimates with 95% confidence intervals.

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  Figure 8. Forest plots of weighted mean differences for (a,b) triglycerides and (c,d) total cholesterol. (a,c) HIIT vs. CON; (b,d) HIIT vs. MICT. CON, non-exercise control; HIIT, high-intensity interval training; MICT, moderate-intensity continuous training. Green squares indicate individual study estimates, with their size reflecting study weights; black diamonds indicate pooled estimates with 95% confidence intervals.

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  Figure 9. Forest plots of weighted mean differences for (a,b) maximal oxygen uptake and (c,d) blood glucose. (a,c) HIIT vs. CON; (b,d) HIIT vs. MICT. CON, non-exercise control; HIIT, high-intensity interval training; MICT, moderate-intensity continuous training. Green squares indicate individual study estimates, with their size reflecting study weights; black diamonds indicate pooled estimates with 95% confidence intervals.