Relationship Between Appetite-Related Hormone And Motivation Of Exercise Behavior In Human

PURPOSE: Previous animal studies have suggested that appetite-related hormones may influence exercise motivation and behavior. Inulin intake has been reported to alter the blood levels of these hormones. This study examined whether the alteration of appetite-related hormones by inulin intervention influences exercise motivation in humans. METHODS: Twenty-six healthy adults (15 men, 11 women, aged 29.6 ± 10.1 years) participated in a 6-week inulin intervention experiment. The participants were randomly divided into inulin (n = 13) and maltodextrin intake (control, n = 13) groups. Blood hormone levels (acyl ghrelin, des-acyl ghrelin, peptide YY [PYY], leptin, and insulin) were measured at baseline and after intervention. Exercise motivation was also assessed using a 20-item tool evaluating affective experience, attitude, and behavioral intention for exercise using a five-point scale. The total score for each factor was calculated. Two-way ANOVA was used to test the interaction effect of the time and treatment. Spearman’s correlation coefficients were determined for the relationships between hormone levels and motivation. In addition, stratified analyses were performed by gender and age. RESULTS: There was no interaction effect of the intervention on hormone levels or exercise motivation. Thus, we analyzed the data without considering the intervention groups. No significant correlation was observed between blood hormone levels and exercise motivation at baseline. However, in men, significant correlations were found between acyl ghrelin levels (r = 0.605, p < 0.05) or leptin levels (r = -0.564, p < 0.05) and the total score for behavioral intention, and between PYY levels (r = -0.601, p < 0.05) and the total score for affective experience. Moreover, alterations in acyl ghrelin or PYY levels after the intervention were significantly correlated with changes in the total score for attitude (r = -0.546 and r = -0.425, respectively, p < 0.05). CONCLUSIONS: No intervention effects were found, but there were significant correlations between appetite-related hormone levels, especially acyl ghrelin and PYY levels, and several exercise motivation factors. This may be candidates for a new approach to exercise motivation and behavior. This study was supported by Grant-in-Aid for Early-Career Scientists.