The Influence Of Prolonged Treadmill Running On Plasma Acylated Ghrelin, Appetite And Energy Intake: 1336

Acylated ghrelin is an appetite stimulating peptide important for energy balance. Exercise augments energy expenditure therefore compensatory changes in acylated ghrelin may be anticipated. PURPOSE: To examine plasma concentrations of acylated ghrelin, appetite and ad libitum energy intake for an extended period following a prolonged bout of treadmill running. METHODS: Following ethical approval, 9 healthy males (age 22.2 ± 0.8 yrs, BMI 23.6 ± 0.4 kg·m-2, VO2max 60.5 ± 1.5 mL·kg-1·min-1; mean ± SEM) undertook 2 main trials (exercise and control) in a random order. Exercise and diet were standardised prior to each 24 h trial. Trials commenced in the morning following an overnight fast. Participants spent 10 h within the laboratory on day 1 of trials (9:00 am - 7:00 pm) and returned the following morning (day 2) for final blood and hunger assessments. At the beginning of the exercise trial participants ran for 1.5 h at 68.8 ± 0.8% of VO2 max and rested for the remainder of the trial. Participants rested throughout the control trial. Ad libitum meals were available at 3 points during the laboratory phase of trials (2.5 - 3, 5.5 - 6, 9 - 9.5 h) and during the overnight period. Hunger perceptions were measured within the laboratory using a visual scale. Plasma acylated ghrelin concentrations were determined via an enzyme immunoassay (SPI BIO, France). RESULTS: Exercise induced a brief suppression of hunger and plasma acylated ghrelin (two-way ANOVA, interaction effect, P < 0.001 for both). Plasma concentrations of acylated ghrelin were significantly lower at the mid-point (control 133 ± 20, exercise 55 ± 15 pg·mL-1) and end (control 135 ± 20, exercise 70 ± 14 pg·mL-1) of exercise. Thereafter, neither acylated ghrelin or hunger were significantly different from control values for the remainder of day 1 or on the morning of day 2. Despite the energy expenditure induced by exercise (5324 ± 186 kJ) energy intake was no different between trials (control 17,191 ± 1144 kJ, exercise 17,606 ± 1384 kJ). Following exercise participants therefore remained in negative energy balance relative to control. CONCLUSION: Prolonged treadmill running briefly suppresses plasma acylated ghrelin and hunger but fails to induce compensatory hunger, acylated ghrelin or energy intake responses in the 22.5 h after exercise.