Moderate‐Intensity Treadmill‐Training and Functional Changes in Solid Meal Gastric Emptying in a Rodent Model

PURPOSE Exercise has long been known for the beneficial effects on numerous systems within the body; it improves cardiovascular function, improves brain functioning and memory, reduces adipose tissue lowering the risk of obesity and associated disorders. But the overall effect of exercise on the gastrointestinal (GI) tract remains unresolved. Patients suffering from GI dysfunction are frequently prescribed physical activity to improve their symptoms. Yet, physical activity has also been shown to provoke GI disturbances including diarrhea, abdominal pain, and gastroesophageal reflux. These GI disturbances commonly occur after bouts of prolonged or high‐intensity exercise, and the GI disturbance frequency is twice as high during running compared to other endurance sports. The effects of upper GI function following exercise are diverse; studies have reported increases, decreases, or no changes in gastric emptying (GE) rate following treadmill‐training. We hypothesize that exercise contributes to beneficial effects on the upper GI tract, like other systems, by altering peripheral and central signaling mechanisms regulating gastric motility. By gaining a greater understanding of the relationship between exercise and gastric functioning, exercise may serve a putative role as medicine in treating a number of upper GI‐related health disorders and dysfunctions (e.g. gastroparesis). METHODS In this study, we evaluated the effects of moderate‐intensity treadmill‐training (66.6% VO 2 max) on GE rate in rats. Male Wistar rats were exercised (n = 8) or placed (n = 8; control) on a treadmill five days week −1 for 8 weeks. Baseline, mid‐point, and final GE measurements were conducted throughout the study. On the days of the GE experiment, rats were fasted overnight with unlimited access to water, and then placed into individual chambers where GE was indirectly measured. Baseline air measurements were collected before the fasted rats received 1g of pancake containing 5μL of the stable isotope [ 13 C]‐octanoic acid. The exhaled breath was collected and analyzed to determine the [ 13 C]‐ to [ 12 C]‐ carbon dioxide ratio. RESULTS Body mass increased over the duration of the study by 41%; however, there were no significant differences between exercise and control rats (325.40±3.11 vs. 325.99±3.06g; p>0.05). Food intake remained similar between exercise and control rats (23.23±0.20 vs. 23.19±0.20; p>0.05). Not surprisingly, mean energy intake (MEI; kcal/100g/day) also revealed no significant differences between exercise and control rats (28.99±0.50 vs. 28.90±0.55; p>0.05). There was no significant difference in GE between the exercise and control group gastric emptying coefficient (5.10±1.37 vs 5.04±0.40; p>0.05). CONCLUSION Moderate‐intensity treadmill‐training for 8‐weeks has no significant effect on anthropometric factors. Interestingly, however, as body mass and food intake increased, MEI decreased. We have validated that moderate‐intensity treadmill running has no significant effect on gastric emptying function but structural adaptations may be occurring prior to functional detection. Support or Funding Information Research & Professional Development Grant (Gettysburg College Provost), Cross‐Disciplinary Science Institute at Gettysburg College (X‐SIG), X‐SIG Student Supply Grant This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .