Objectives: To describe the nutrition behaviors, perceptions, and beliefs of marathoners. Methods: A survey-based study was conducted with 422 recent marathon finishers (199 men, 223 women). Participants reported their running background, demographics, diets followed, supplements used, and food/fluid intake during their most recent marathon (median 7 days prior), as well as beliefs about hydration, fueling, and sources of nutrition information. Results: Median finishing times were 3:53 (3:26–4:35) and 4:25 (3:50–4:59) h:min for men and women during their most recent marathon. Most participants (66.1%) reported typically following a moderate-carbohydrate, moderate-fat diet, while 66.4% carbohydrate-loaded prior to their most recent marathon. Among 139 participants following a specific diet over the past year, the most common were vegetarian/vegan/pescatarian (n = 39), Paleolithic (n = 16), gluten-free (n = 15), and low-carbohydrate (n = 12). Roughly 35% of participants took a supplement intended to improve running performance over the past month. Women were more likely to follow specific diets (39.0% vs. 26.1%), while men were more likely to recently use performance-enhancing supplements (40.2% vs. 30.0%). Most participants (68.3%) indicated they were likely or very likely to rely on a structured plan to determine fluid intake, and 75% were confident in their ability to hydrate. At least 35.6% of participants thought they could improve marathon performance by 8% or more with nutrition interventions. Scientific journals ranked as the most reliable source of nutrition information, while running coaches ranked as the most likely source to be utilized. Conclusions: Findings from this investigation, such as diets and supplements utilized by marathoners, can be used by practitioners and researchers alike to improve the dissemination of scientifically-based information on nutrition and marathon running.

Numerous causes of exercise-related gastrointestinal (GI) distress exist but scarce research has evaluated potential psychological causes. Runners (74 men, 76 women) prospectively recorded running duration, intensity (Rating of Perceived Exertion [RPE]), and GI symptoms for 30 days. Six GI symptoms were rated on a 0–10 scale. The percentage of runs over 30 days that participants reported at least one upper, lower, or any GI symptom ≥3 was calculated. After 30 days, participants completed a questionnaire on GI distress triggers (demographics, anthropometrics, experience, analgesic use, antibiotic use, probiotic consumption, fluid/food intake, stress, anxiety). Stress and anxiety were measured via the Perceived Stress Scale (PSS) and Beck Anxiety Inventory (BAI). The median percentage of runs that participants experienced at least one GI symptom ≥3 was 45.6% (interquartile range [IQR], 16.6–67.3%). Age and running experience negatively correlated with GI distress occurrence (rho = −0.17 to −0.34; p < 0.05). Run RPE, probiotic food consumption, PSS scores, and BAI scores positively correlated with GI distress occurrence (rho = 0.18 to 0.36; p < 0.05). Associations between GI distress, stress and anxiety remained significant after adjustment for covariates, except for lower GI symptoms. This study suggests that stress and anxiety contribute to running-related GI distress.

Gastrointestinal (GI) symptoms may affect up to 90% of competitors during endurance races. Studies have typically assessed GI symptoms retrospectively or only over an acute timeframe, and information on the validity and reliability of the questionnaires employed is lacking. This investigation aimed to estimate the frequency of GI distress experienced by runners over 30 days and to establish the validity and reliability of a retrospective GI symptom questionnaire. Runners (70 men, 75 women) recorded GI symptoms with a prospective journal for 30 days. Retrospective GI symptom data were then collected after the 30-day period on two occasions within one week. GI symptoms were rated on a 0–10 scale. Descriptive statistics for GI symptoms are reported as medians (interquartile ranges) because of nonnormal distributions. Men and women experienced at least one GI symptom on 84.0% (59.8–95.1%) and 78.3% (50.0–95.2%) of runs, respectively. Moderate-to-severe GI symptoms (score of ≥5) were experienced on 13.8% (6.7–37.3%) and 21.7% (5.3–41.2%) of runs for men and women. Spearman’s rho correlations between journal ratings and retrospective questionnaire ratings ranged from 0.47 to 0.82 (all p < .001), although they were highest when journal ratings were quantified as mean 30-day values (all rho ≥ 0.59). Reliability of the retrospective questionnaire ratings was high (rho = 0.78–0.92; p < .001). In comparison with tracking GI symptoms with a daily journal, retrospective questionnaires seem to offer a convenient and reasonably valid and reliable method of quantifying GI symptoms over 30 days.

Exercise-associated gastrointestinal (GI) distress can negatively impact athletic performance and interfere with exercise training. Although there are a few universal underlying causes of GI distress, each symptom often has its own unique triggers and, therefore, its own prevention and management strategies. One of the most troubling GI symptoms an athlete can experience during training and competition is nausea/vomiting. The prevalence of nausea varies with several factors, two of the most important being exercise intensity and duration. Relatively brief, high-intensity exercise (e.g., sprinting, tempo runs) and ultra-endurance exercise are both associated with more frequent and severe nausea. The potential causes of nausea in sport are numerous and can include catecholamine secretion, hypohydration, heat stress, hyponatremia, altitude exposure, excessive fluid/food consumption, hypertonic beverage intake, pre-exercise intake of fatty- or protein-rich foods (especially in close proximity to exercise), prolonged fasting, various supplements (caffeine, sodium bicarbonate, ketones), certain drugs (antibiotics, opioids), GI infections, and competition-related anxiety. Beyond directly addressing these aforementioned causes, antiemetic drugs (e.g., ondansetron) may also be useful for alleviating nausea in some competitive situations. Given the commonness of nausea in sport and its potential impact on exercise performance, athletes and sports medicine practitioners should be aware of the origins of nausea and strategies for dealing with this troublesome gut complaint.