A single session of treadmill running has no effect on plasma total ghrelin concentrations

Ghrelin is a hormone that stimulates hunger. Intense exercise has been shown to temporarily suppress hunger after exercise. In the present study, we investigated whether post-exercise hunger suppression is mediated by reduced plasma total ghrelin concentrations. Nine men and nine women participated in the study. Their mean physical characteristics were as follows: age 24.8 (s_x = 0.9) years, body mass index 22.9 (s_x = 0.6) kg · m^-2, maximal oxygen uptake (VO_2max) 57.7 (s_x = 2.2) ml · kg^-1 · min^-1. The participants completed two 3-h trials (exercise and control) on separate days in a randomized balanced design after overnight fasts. The exercise trial involved a 1-h treadmill run at 73.5% of VO_2max followed by 2 h of rest. The control trial consisted of 3 h of rest. Blood samples were collected at 0, 0.5, 1, 1.5, 2, and 3 h. Total ghrelin concentrations were determined from plasma. Hunger was assessed following blood sampling using a 15-point scale. The data were analysed using repeated-measures analysis of variance. Hunger scores were lower in the exercise trial than in the control trial (trial, P = 0.009; time, P < 0.001; trial × time, P < 0.001). Plasma total ghrelin concentrations did not differ between trials. These findings indicate that treadmill running suppresses hunger but this effect is not mediated by changes in plasma total ghrelin concentration.