Journal of Applied Physiology, Vol 68, Issue 4 1350-1353, Copyright © 1990 by American Physiological Society
Orocecal transit during mild exercise in women
W. F. Keeling, A. Harris and B. J. Martin
Medical Sciences Program, Indiana University School of Medicine, Bloomington 47405.
Little is known of the influence of exercise on movement of ingested food
through the alimentary tract or of the association of several
gastrointestinal hormones with transit rate in exercise. In this study,
orocecal transit during mild exercise was measured in 21 women by detecting
a rise in expired H2 after ingestion of 20 g lactulose in a 350-ml (360
kcal) liquid meal. Motilin, gastrin, and cortisol were measured in
peripheral venous blood when, as evidenced by a breath H2 rise, the first
portion of the meal arrived at the cecum. Comparison was made between
seated rest and a treadmill walk at 5.6 km/h up a 2% grade. The walk
predictably elevated heart rate, O2 uptake, and rectal temperature and also
reduced transit time from 98 min at rest to 75 min during exercise (P less
than 0.001). Faster transit in exercise was associated with a significant
rise in cortisol, while gastrin and motilin levels were both unchanged. In
conclusion, in women mild concurrent exercise accelerates orocecal transit
rate of at least the first portion of nonabsorbable carbohydrate in a
liquid meal. Although the mechanism for the effect remains unknown, it may
be secondary to some aspect of the stress response to physical activity.
