Case Series: Management of Exercise-Associated Gastrointestinal Symptoms in Endurance Athletes Using a High-Carbohydrate Low-FODMAP Therapeutic Intervention

This case-series describes a four-phase management approach implementing gastrointestinal assessment during exercise (GastroAxEx) to develop therapeutic interventions for athletes affected by exercise-associated gastrointestinal symptoms (Ex-GIS). Recreational to elite-level athletes who experienced recurrent severe Ex-GIS (n = 9) and controls (n = 2) (without Ex-GIS) volunteered to participate in the case series. The four-phased approach involved a clinical assessment (Phase 1), a standardized laboratory GastroAxEx where physiological strain and GIS data were collected (Phase 2), individualized therapeutic intervention and management strategies based on Phase 2 outcomes that specifically included implementation of a 48-hr high carbohydrate low FODMAP diet (Phase 3), and the monitoring and adjustment of therapeutic interventions (Phase 4). The majority of athletes (n = 6/9) consumed <400 ml/hr of fluid ad libitum, resulting in 2%-4% body mass loss, and <40 g/hr of exogenous carbohydrate (n = 8/9), during the GastroAxEx. Severe Ex-GIS (predominantly loose stools) was reported by n = 4/9 athletes, whereas n = 8/9 athletes reported severe Ex-GIS (predominantly loose stools) in the recovery period. All athletes reported low food and fluid intake tolerance during exercise and recovery. Orocecal transit time was slow or delayed for n = 2/9 athletes. Most athletes (n = 8/9) successfully implemented a 48-hr high carbohydrate low FODMAP prior to and improved intake tolerance during the targeted event. In addition, the incidence and severity of Ex-GIS were reduced, resulting in improved perceived work output during the targeted events. A 48-hr high carbohydrate low FODMAP before endurance exercise appears to be a valuable addition to suggested therapeutic interventions used to mitigate Ex-GIS.