Summary coding of studies examining the effect of HIIT on cardiometabolic health variables
| Normal weight population | Overweight/obese population | ||||
|---|---|---|---|---|---|
| HIIT duration ion | Marker | n/N (%)*†‡ | Effect (0/−/+/?)§ | n/N (%)*†‡ | Effect (0/−/+/?)§ |
| ST-HIIT | BM | NR | NA | NR | NA |
| BMI | NR | NA | 1/4 (25%) | No (0) | |
| WC | 0/2 (0%) | No (0) | 2/3 (67%) | Positive (+) | |
| WHR | 0/1 (0%) | NA | 0/0 (0%) | NA | |
| % BF | NR | NA | NR | NA | |
| RHR | NR | NA | 1/3 (33%) | No (0) | |
| VO2 max | NR | NA | NR | NA | |
| SBP | NR | NA | NR | NA | |
| DBP | NR | NA | NR | NA | |
| FG | 2/4 (50%) | Inconsistent (?) | NR | NA | |
| FI | 0/2 (0%) | No (0) | NR | NA | |
| HbA1c | 0/0 (0%) | NA | 1/1 (100%) | NA | |
| TC | 1/2 (50%) | Inconsistent (?) | 1/3 (33%) | No (0) | |
| HDL | 1/3 (33%) | No (0) | 0/4 (0%) | No (00) | |
| LDL | 1/2 (50%) | Inconsistent (?) | 1/3 (33%) | No (0) | |
| TG | 0/2 (0%) | No (0) | 0/5 (0%) | No (00) | |
| CRP | 0/0 (0%) | NA | 0/1 (0%) | NA | |
| IL-6 | 1/2 (50%) | Inconsistent (?) | 0/1 (0%) | NA | |
| TNF-α | 0/1 (0%) | NA | 0/1 (0%) | NA | |
| LT-HIIT | BM | 0/1 (0%) | NA | NR | NA |
| BMI | 0/1 (0%) | NA | NR | NA | |
| WC | 0/0 (0%) | NA | NR | NA | |
| WHR | 0/0 (0%) | NA | 2/4 (50%) | Inconsistent (?) | |
| % BF | 0/0 (0%) | NA | NR | NA | |
| RHR | 0/2 (0%) | No (0) | NR | NA | |
| VO2 max | 4/4 (100%) | Positive (++) | NR | NA | |
| SBP | 1/2 (50%) | Inconsistent (?) | NR | NA | |
| DBP | 1/2 (50%) | Inconsistent (?) | NR | NA | |
| FG | 0/2 (0%) | No (0) | NR | NA | |
| FI | 1/1 (100%) | NA | 0/3 (0%) | No (0) | |
| HbA1c | 0/0 (0%) | NA | 1/5 (20%) | No (00) | |
| TC | 0/2 (0%) | No (0) | NR | NA | |
| HDL | 0/2 (0%) | No (0) | NR | NA | |
| LDL | 0/1 (0%) | NA | NR | NA | |
| TG | 0/2 (0%) | No (0) | NR | NA | |
| CRP | 0/0 (0%) | NA | NR | NA | |
| IL-6 | 0/0 (0%) | NA | 0/2 (0%) | No (0) | |
| TNF-α | 0/0 (0%) | NA | 1/1 (100%) | NA | |
*n=number of studies reporting difference in the expected direction.
†N=number of identified studies of interest.
‡(%)=percentage of studies reporting differences in the expected direction.
§Summary effect. No effect (0): 0–33% of studies reported significant differences; inconsistent (?): 34–59% of studies reported significant differences; positive (+) or negative (−) effect: 60–100% of studies demonstrated significant differences; ≥4 studies: positive (++), negative (−−), no effect (00), inconsistent findings (??).
% BF, body fat percentage; BM, body mass; BMI, body mass index; CRP, C reactive protein; DBP, diastolic blood pressure; FG, fasting glucose; FI, fasting insulin; HbA1c, glycosylated haemoglobin; HDL, high-density lipoprotein cholesterol; HIIT, high-intensity interval training; IL-6, interleukin 6; LDL, low-density lipoprotein cholesterol; NA, not applicable; NR, no reported summary coding (a meta-analysis was performed); RHR, resting heart rate; SBP, systolic blood pressure; TC, total cholesterol; TG, triglycerides; TNF-α, tumour necrosis factor-α; VO2 max, maximal oxygen uptake; WC, waist circumference; WHR, waist-to-hip ratio.