Table 2

Summary coding of studies examining the effect of HIIT on cardiometabolic health variables

Normal weight populationOverweight/obese population
HIIT duration ionMarkern/N (%)*†‡Effect (0/−/+/?)§n/N (%)*†‡Effect (0/−/+/?)§
BMINRNA1/4 (25%)No (0)
WC0/2 (0%)No (0)2/3 (67%)Positive (+)
WHR0/1 (0%)NA0/0 (0%)NA
RHRNRNA1/3 (33%)No (0)
FG2/4 (50%)Inconsistent (?)NRNA
FI0/2 (0%)No (0)NRNA
HbA1c0/0 (0%)NA1/1 (100%)NA
TC1/2 (50%)Inconsistent (?)1/3 (33%)No (0)
HDL1/3 (33%)No (0)0/4 (0%)No (00)
LDL1/2 (50%)Inconsistent (?)1/3 (33%)No (0)
TG0/2 (0%)No (0)0/5 (0%)No (00)
CRP0/0 (0%)NA0/1 (0%)NA
IL-61/2 (50%)Inconsistent (?)0/1 (0%)NA
TNF-α0/1 (0%)NA0/1 (0%)NA
WC0/0 (0%)NANRNA
WHR0/0 (0%)NA2/4 (50%)Inconsistent (?)
% BF0/0 (0%)NANRNA
RHR0/2 (0%)No (0)NRNA
VO2 max4/4 (100%)Positive (++)NRNA
SBP1/2 (50%)Inconsistent (?)NRNA
DBP1/2 (50%)Inconsistent (?)NRNA
FG0/2 (0%)No (0)NRNA
FI1/1 (100%)NA0/3 (0%)No (0)
HbA1c0/0 (0%)NA1/5 (20%)No (00)
TC0/2 (0%)No (0)NRNA
HDL0/2 (0%)No (0)NRNA
TG0/2 (0%)No (0)NRNA
IL-60/0 (0%)NA0/2 (0%)No (0)
TNF-α0/0 (0%)NA1/1 (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.