Acute high-intensity interval exercise is superior to moderate-intensity continuous exercise in enhancing endothelial function and its associated biomarkers in sedentary young individuals: the possible involvement of lactate

Fig. 1. Experimental design HIIE: high-intensity interval exercise; MICE: moderate-intensity continuous exercise; CON: control.

Fig. 2. Exercise protocols HIIE: high-intensity interval exercise; MICE: moderate-intensity continuous exercise; CON: control.

Fig. 3. Effects of acute HIIE and MICE on endothelial function-related indicators in sedentary young individuals The statistical analyses showed the levels of baseline diameter (A), peak diameter (B), mean blood pressure (C), MSR (D), FMD% (E), and absolute FMD (F) in the pre- and post-visits of HIIE, MICE, and CON conditions. ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001 vs pre-visit; ###P < 0.001 vs CON; $P < 0.05, $$P < 0.01, $$$P < 0.001 vs MICE. Data are the Mean ± SD. HIIE: high-intensity interval exercise; MICE: moderate-intensity continuous exercise; CON: control; FMD%: percent flow-mediated dilation; AbsFMD: absolute FMD; MSR: mean shear rate.

Fig. 4. Effects of acute HIIE and MICE on blood biomarkers in sedentary young individuals The statistical analyses showed the levels of blood lactate (A), VEGF (B), IGF-1 (C), and irisin (D) in the pre- and post-visits of HIIE, MICE, and CON conditions. ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001 vs pre-visit; ##P < 0.01, ###P < 0.001 vs CON; $P < 0.05, $$$P < 0.001 vs MICE. HIIE: high-intensity interval exercise; MICE: moderate-intensity continuous exercise; CON: control; VEGF: vascular endothelial growth factor; IGF-1: insulin-like growth factor.

Fig. 5. Correlation analyses of vascular endothelial function variables Spearman correlation analyses showed a correlation between change in FMD% and change in mean shear rate (A), change in blood lactate (B), or VEGF (C). Spearman correlation analyses showed a correlation between change in mean shear rate and change in blood lactate (D), change in VEGF (E), or change in IGF-1 (F). Spearman correlation analyses showed a correlation between change in blood lactate and change in VEGF (G) or change in IGF-1 (H). Spearman correlation analysis showed a correlation between change in VEGF and change in IGF-1 (I). Values are the Spearman's correlation coefficients/P value. FMD%: percent flow-mediated dilation; VEGF: vascular endothelial growth factor; IGF-1: insulin-like growth factor.

Fig. 6. Mediation analyses Mediation models showed the relationship between change in MSR and change in FMD% induced by HIIE (A) or MICE (B) with VEGF as a mediator. Mediation models showed the relationship between change in lactate and change in FMD% induced by HIIE (C) or MICE (D) with VEGF as a mediator. Data are unstandardized regression coefficient (P-value). FMD%: percent flow-mediated dilation; MSR: mean shear rate; VEGF: vascular endothelial growth factor.