Effects of exercise on mesenteric blood flow in man

Area of Science:

• Physiology
• Gastroenterology
• Vascular Biology

Background:

• Superior mesenteric artery (SMA) blood flow is crucial for nutrient absorption.
• The impact of acute exercise on SMA blood flow, particularly in the postprandial state, requires further elucidation.

Purpose of the Study:

• To investigate the effects of acute treadmill exercise on SMA blood flow in fasting and postprandial states.
• To compare the SMA blood flow response to a meal alone versus a combined exercise and meal stimulus.

Main Methods:

• Transcutaneous Doppler ultrasound was employed to measure SMA blood flow.
• Participants underwent standardized treadmill exercise (5 km/h, 20% gradient, 15 min).
• SMA blood flow was assessed immediately after exercise and at 5 and 10 minutes post-exercise, as well as in response to a liquid meal with and without prior exercise.

Main Results:

• Immediately post-exercise, SMA blood flow decreased by 43%, with reductions of 29% at 5 minutes and 24% at 10 minutes.
• The combined exercise and meal stimulus resulted in a significantly smaller SMA blood flow response at 5 minutes post-stimulus compared to the meal alone (635 ± 51 ml/min vs. 846 ± 72 ml/min, p < 0.025).
• No significant differences in SMA blood flow were observed at other time points between the meal alone and combined stimuli.

Conclusions:

• Acute exercise demonstrably reduces mesenteric blood flow in healthy subjects.
• Exercise attenuates the postprandial hyperemic response to a meal, indicating a redistribution of blood flow away from the mesenteric circulation during and after physical exertion.