Effect of food intake on the ventilatory response to increasing core temperature during exercise

Abstract

Food intake increases metabolism and body temperature, which may in turn influence ventilatory responses. Our aim was to assess the effect of food intake on ventilatory sensitivity to rising core temperature during exercise. Nine healthy male subjects exercised on a cycle ergometer at 50% of peak oxygen uptake in sessions with and without prior food intake. Ventilatory sensitivity to rising core temperature was defined by the slopes of regression lines relating ventilatory parameters to core temperature. Mean skin temperature, mean body temperature (calculated from esophageal temperature and mean skin temperature), oxygen uptake, carbon dioxide elimination, minute ventilation, alveolar ventilation, and tidal volume (VT) were all significantly higher at baseline in sessions with food intake than without food intake. During exercise, esophageal temperature, mean skin temperature, mean body temperature, carbon dioxide elimination, and end-tidal CO2 pressure were all significantly higher in sessions with food intake than without it. By contrast, ventilatory parameters did not differ between sessions with and without food intake, with the exception of VT during the first 5 min of exercise. The ventilatory sensitivities to rising core temperature also did not differ, with the exception of an early transient effect on VT. Food intake increases body temperature before and during exercise. Other than during the first 5 min of exercise, food intake does not affect ventilatory parameters during exercise, despite elevation of both body temperature and metabolism. Thus, with the exception of an early transient effect on VT, ventilatory sensitivity to rising core temperature is not affected by food intake.

Effect of food intake on respiratory chemosensitivity to CO2 in young adults

“…From these findings, it is plausible that respiratory chemosensitivity to CO 2 is increased during exercise after food intake. However, our previous study [1] did not reveal higher V E during exercise after food intake. From that finding, we hypothesized that V E remains steady as a result of redundant compensatory mechanisms [1, 9].…”

“…It is well known that food intake influences several physiological parameters. For example, food intake increases metabolism and body temperature [1–3]. This is the so-called postprandial thermogenesis or thermic effect of food.…”

“…This is the so-called postprandial thermogenesis or thermic effect of food. We recently reported that food intake also influences the respiratory response at rest [1]—i.e., food intake increases minute ventilation ( V E ) in resting young individuals. In that study, we speculated that this elevation in V E was caused by an elevation in the H + ion concentration related to increases in CO 2 output ( V CO 2 ) and the plasma noradrenaline concentration [4], which can be induced by an increase in sympathetic nervous system activity [5].…”

“…Young adults in that study exercised at 50% of peak oxygen uptake 90 min after food intake, and the increase in metabolism elicited by the food intake was still present during the subsequent exercise. Interestingly, we found that although V CO 2 and end-tidal PCO 2 (P ET CO 2 ) were increased by food intake during exercise, V E was not [1]. On the other hand, when we previously compared the ventilatory responses during exercise with participants breathing CO 2 -enriched air or room air, we found that breathing CO 2 -enriched air elevated PCO 2 and V E [6].…”

Effects of Casein Hydrolysate Ingestion on Thermoregulatory Responses in Healthy Adults during Exercise in Heated Conditions: A Randomized Crossover Trial

“…Several factors potentially affect core body temperature (Tco) and skin temperature independent of exercise-induced heat production. For example, food ingestion has been shown to elevate Tco associated with an increase in postprandial energy expenditure [7,8] which delays Tco threshold for thermoregulatory cutaneous vasodilation during exercise [9]. The type of nutrients also influences postprandial energy expenditure and possibly Tco since a greater energy consumption has been reported after protein intake compared with an equivalent amount of carbohydrate ingestion through encouraging protein synthesis and mitochondrial enzymatic activity [10,11].…”