Effects Of Exercise On Appetite And Whole Saliva in Humans

Abstract

We previously confirmed that the sight and smell of food enhance appetite and salivary flow, and decrease salivary viscosity. PURPOSE AND METHODS: To examine the effect of exercise on appetite and the characteristics of saliva, six subjects performed high-intensity exercise for 12 min [2.0 and 1.6 W/kg (weight) for males and females, respectively] and low-intensity exercise for 24 min [1.0 and 0.8 W/kg (weight) for males and females, respectively] after a 3-min baseline. Then subjects rested for 36 min as a recovery phase. Whole saliva was collected for 3 min at the baseline and every 12 min during exercise and recovery phase. Subjects rated prospective food consumption on a 100-mm visual analog scale (Question: How much food do you think you could eat? Answer: 0 = nothing at all, 100 = a large amount). Subjects placed a nylon ball (15 mm in diameter) in their oral cavity to promote salivary flow. We then measured the flow and viscosity of saliva. RESULTS: The rate of prospective food consumption increased 30 min after the end of low-intensity exercise (p < 0.05), but did not change during and after high-intensity exercise. Compared to the resting baseline, salivary flow significantly decreased during high-intensity exercise, but not during and after low-intensity exercise. The viscosity of saliva did not significantly change in response to exercise. There was no significant correlation between the changes in appetite and saliva variables. CONCLUSION: These results suggest that the effects of exercise on appetite and salivary flow depend on the intensity of the exercise, and that the change in appetite associated with exercise does not relate to the characteristics of saliva. Supported by a grant from the Asahi Brewries Foundation awarded to NH.