The interrelationship among exercise intensity, endothelial function, and ghrelin in healthy humans

Ghrelin circulates in acylated (AG) and deacylated (DAG) isoforms and both may impact endothelial function (EF). Although acute exercise has been shown to modulate ghrelin levels and EF, data on the impact of exercise intensity on these parameters are scarce. To investigate the effect of exercise intensity and sex on EF and ghrelin levels, nine males (age: 43.8 ± 10.3 y; BMI: 22.5 ± 1.8 kg/m²) and eight females (age: 33.75 ± 10.2 y; BMI: 22.4 ± 1.6 kg/m²) completed a maximal cycle ergometer lactate threshold (LT)/VO_2peak test. This test determined the exercise intensity for three visits: (a) CON, no exercise; (b) MOD, the power output (PO) at LT; (c) HIGH, the PO associated with 75% of the difference between LT and VO_2peak. Ghrelin levels and EF [flow-mediated dilation (FMD), shear rate (SR)] were measured at baseline and then 30-120 min post-exercise. HIGH and MOD increased FMD (p < 0.0001). Each ghrelin isoform was suppressed by HIGH; only females exhibited reduced DAG levels in HIGH compared to MOD and CON (p < 0.0001-0.004). FMD was associated with ghrelin levels in females (r = -0.26-0.47). High-intensity exercise is key for ghrelin suppression and appears to only be weakly/moderately related to EF.