Gastrointestinal mucosal integrity after prolonged exercise with fluid supplementation

Purpose: Studies on the effect of exercise on gastrointestinal (GI) mucosal integrity have been limited to occult-blood tests, which were often nonspe cific for human blood. The aim of our study was to investigate more aspects of this integrity. Methods: We examined the effect of prolonged exercise a nd carbohydrate (CHO) supplementation on mucosal integrity in 22 male triat hletes by measuring fecal lysozyme, alpha 1-antitrypsin, and occult-blood l oss, which was examined by two rests specific for human blood (Colon Albumi n and Monohaem test). Exercise consisted of two 150-min tests (alternativel y running, cycling, and running at 70-75% (V) over dotO(2max)), either with a 7.0% CHO drink or water (W). Furthermore, GI symptoms during exercise we re registered by questionnaire. Results: Three subjects showed human albumi n only in the first stool after exercise: twice with W and once with CHO. H owever, human hemoglobin (Hb) could not be detected in these samples. Four other subjects showed an elevated lysozyme concentration after exercise wit h CHO but not with W. Elevated alpha 1-antitrypsin values were found in thr ee of seven specimens in which either positive albumin tests and/or an elev ated lysozyme concentration were demonstrated. Twenty-one subjects (95%) re ported one or more GI symptoms during exercise. Incidence rates of differen t GI symptoms varied from 5 to 68%. Most symptoms were more frequent and la sted longer during running than during cycling but did not differ significa ntly between supplements and were not related to any mucosal integrity para meter. Conclusions: GI blood loss during exercise is of no clinical importa nce, at least in our study design with a group of well-trained male subject s who consumed a relatively high amount of fluid (up to 2.3 L). Nevertheles s, an increased alpha 1-antitrypsin and lysozyme concentration may indicate a transient local mucosal damage with an inflammatory response.