Sustained Strenuous Exercise Increases Intestinal Permeability in Racing Alaskan Sled Dogs

Abstract

We assessed gastric and intestinal permeability and performed gastroscopy to evaluate the effects of sustained strenuous exercise on the gastrointestinal tract in racing sled dogs. Three teams of racing Alaskan sled dogs were examined approximately 1 week before and 24 hours after the 2003 Iditarod sled dog race (1,100 miles in 10 days). Each examination consisted of the administration of a solution of sucrose, lactulose, and rhamnose to evaluate gastric and intestinal permeability, as well as gastroscopy to visually inspect the gastric mucosa. Of the 54 dogs examined before the race, 16 completed the course and contributed data to the analysis. Sustained strenuous exercise was associated with an increased frequency of gastric erosions or ulcerations seen endoscopically (0% prerace versus 61% postrace). A significant postrace increase occurred in the median lactulose to rhamnose ratio in both serum and urine (0.11 versus 0.165, P = .0363; 0.11 versus 0.165, P = .0090, respectively). No significant differences were found in median serum or urinary sucrose concentrations when pre- and postrace values were compared. No correlation was found between visible gastric lesions and the concentration of sucrose in serum or urine samples obtained 4-5 hours after administration of the sugar solutions. We conclude that sustained strenuous exercise is associated with increased intestinal permeability, but the sucrose permeability test as we performed it did not correlate with visible gastric lesions.

Effect of exercise on chemically-induced colitis in adiponectin deficient mice

“…The mechanism(s) by which exercise affects the gastrointestinal (GI) tract in individuals with IBD is poorly understood, however, decreased blood flow, increased GI motility and permeability, increased mechanical bouncing and increased metabolic stress via neuro-immuno-endocrine alterations have all been suggested to be potentially harmful [5,34,41-43]. Nevertheless, these prospectively harmful effects of exercise have only been investigated following acute bouts of strenuous exercise [5,43,44] and therefore may not be predictive of the long-term consequences of habitual exercise training of a moderate intensity [41].…”

“…Nevertheless, these prospectively harmful effects of exercise have only been investigated following acute bouts of strenuous exercise [5,43,44] and therefore may not be predictive of the long-term consequences of habitual exercise training of a moderate intensity [41]. A major finding of this study was that exercise behavior was not altered in any of the DSS-treated animals, who were able to maintain the prescribed training protocol (without any increased encouragement) for the duration of the study.…”

Exercise induced hypercoagulability, increased von Willebrand factor and decreased thyroid hormone concentrations in sled dogs

“…The induction of increased procoagulant activity could be speculated to be caused by platelets activated by absorbed intestinal endotoxin [22], as increased intestinal permeability has been demonstrated in sled dogs [21,23] or by the proinflammatory state documented by the increased CRP after the 68 km sled pull. Other procoagulant activating mechanisms could include neutrophil activation, which in turn activates platelets and vice versa [24].…”

Peptic Ulcer and Exercise

“…Races that can cover 160 km/day increase intestinal permeability [31], worsen ulceration [30], and sometimes lead to death during the event [32]. Excessive wheel running also causes peptic ulcers in laboratory rats.…”