Observation Of Gastrointestinal Symptoms During The Boston Marathon

Marathon running presents a unique exercise-related stress for myriad body systems. Previous literature suggests heat stress, nonsteroidal anti-inflammatory drug (NSAID) ingestion and course specifics (e.g. net grade) may contribute to gut permeability and gastrointestinal (GI) stress. The Boston Marathon involves a net downhill course, variable environmental conditions and a competitive field of qualified runners with faster finish times than other events. PURPOSE: Observe GI total symptom scores while competing in the 2024 Boston Marathon (20.4 ± 3.8 °C, 42 ± 12% relative humidity). METHODS: Seventy-seven healthy, qualified runners (38 females: 46 ± 12y, 1.67 ± .09 m, 60.54 ± 9.06 kg, 3.75 ± 0.54 hr finish time; 39 males: 53 ± 11y, 1.73 ± .09 m, 68.11 ± 9.68 kg; 3.66 ± 0.52 hr finish time) voluntarily reported to a research tent pre-race (within 1 hr of start) and post-race to complete GI symptom surveys. A total GI symptom score was quantified as a sum of symptom severity (rated 0-10) for each of 25 total symptoms. GI symptom scores were compared in a subset for those who reported NSAID ingestion during the race (n = 10). Repeated measures ANOVA and paired-samples t-tests were used to compare data with significance set as p < .05. RESULTS: Overall, GI symptom scores significantly increased from pre-race (10 ± 10) to post-race (28 ± 17; p < .001). Despite females reporting slightly greater symptom scores post-race (30 ± 17) compared to males (24 ± 15), there were no significant sex differences in GI symptom scores (p = .076). Interestingly, the most common symptoms pre-race were ‘urge to urinate’ (66%), ‘thirst’ (48%), and ‘loose stool’ (29%). Post-race, ‘muscle soreness’ (91%), ‘tired/fatigued’ (87%), and ‘thirst’ (77%) were most reported. Mean increase in GI symptom score was 18 ± 16 in non-NSAID users, while NSAID users reported an increase of 18 ± 13 (p > .05). CONCLUSIONS: GI symptoms appear highly individualized and variable, which is consistent with previous literature. The marathon represents an overall stressful event for the GI system and symptoms seem inherent in this population. Future research should continue to investigate common triggers to symptom exacerbation and biomarker indications of symptom severity. This will help inform potentially effective GI symptom preventive measures for endurance runners. Supported by: This study was funded by the Boston Athletic Association Medical Research Grant Program.