Influence of prolonged treadmill running on appetite, energy intake and circulating concentrations of acylated ghrelin

Abstract

The effects of prolonged treadmill running on appetite, energy intake and acylated ghrelin (an appetite stimulating hormone) were examined in 9 healthy males over the course of 24h. Participants completed 2 experimental trials (exercise and control) in a randomised-crossover fashion. In the exercise trial participants ran for 90min at 68.8±0.8% of maximum oxygen uptake followed by 8.5h of rest. Participants returned to the laboratory on the following morning to provide a fasting blood sample and ratings of appetite (24h measurement). No exercise was performed on the control trial. Appetite was measured within the laboratory using visual analogue scales and energy intake was assessed from ad libitum buffet meals. Acylated ghrelin was determined from plasma using an ELISA assay. Exercise transiently suppressed appetite and acylated ghrelin but each remained no different from control values in the hours afterwards. Furthermore, despite participants expending 5324kJ during exercise there was no compensatory increase in energy intake (24h energy intake; control 17,191kJ, exercise 17,606kJ). These findings suggest that large energy deficits induced by exercise do not lead to acute compensatory responses in appetite, energy intake or acylated ghrelin.