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BackgroundDebilitating gastrointestinal symptoms (GIS) and dermatological injuries (DI) are common during and after endurance events and have been linked to performance decrements, event withdrawal, and issues requiring medical attention. The study aimed to determine whether GIS and DI affect food and fluid intake, and nutritional and hydration status, of ultramarathon runners during multi-stage (MSUM) and 24-h continuous (24 h) ultramarathons.MethodsAd libitum food and fluid intakes of ultramarathon runners (MSUM n = 54; 24 h n = 22) were recorded throughout both events and analysed by dietary analysis software. Body mass and urinary ketones were determined, and blood samples were taken, before and immediately after running. A medical log was used to monitor symptoms and injuries throughout both events.ResultsGIS were reported by 85 and 73 % of ultramarathon runners throughout MSUM and 24 h, respectively. GIS during MSUM were associated with reduced total daily, during, and post-stage energy and macronutrient intakes (p < 0.05), whereas GIS during 24 h did not alter nutritional variables. Throughout the MSUM 89 % of ultramarathon runners reported DI. DI during MSUM were associated with reduced carbohydrate (p < 0.05) intake during running and protein intake post-stage (p < 0.05). DI during 24 h were low; thus, comparative analyses were not possible. Daily, during running, and post-stage energy, macronutrient and water intake variables were observed to be lower with severity of GIS and DI (p < 0.05) throughout the MSUM only.ConclusionsGIS during the MSUM, but not the 24 h, compromised nutritional intake. DI presence and severity also compromised nutrient intake during running and recovery in the MSUM.

BackgroundAnecdotal evidence suggests ultra-runners may not be consuming sufficient water through foods and fluids to maintenance euhydration, and present sub-optimal sodium intakes, throughout multi-stage ultra-marathon (MSUM) competitions in the heat. Subsequently, the aims were primarily to assess water and sodium intake habits of recreational ultra-runners during a five stage 225 km semi self-sufficient MSUM conducted in a hot ambient environment (Tmax range: 32°C to 40°C); simultaneously to monitor serum sodium concentration, and hydration status using multiple hydration assessment techniques.MethodsTotal daily, pre-stage, during running, and post-stage water and sodium ingestion of ultra-endurance runners (UER, n = 74) and control (CON, n = 12) through foods and fluids were recorded on Stages 1 to 4 by trained dietetic researchers using dietary recall interview technique, and analysed through dietary analysis software. Body mass (BM), hydration status, and serum sodium concentration were determined pre- and post-Stages 1 to 5.ResultsWater (overall mean (SD): total daily 7.7 (1.5) L/day, during running 732 (183) ml/h) and sodium (total daily 3.9 (1.3) g/day, during running 270 (151) mg/L) ingestion did not differ between stages in UER (p < 0.001 vs. CON). Exercise-induced BM loss was 2.4 (1.2)% (p < 0.001). Pre- to post-stage BM gains were observed in 26% of UER along competition. Pre- and post-stage plasma osmolality remained within normal clinical reference range (280 to 303 mOsmol/kg) in the majority of UER (p > 0.05 vs. CON pre-stage). Asymptomatic hyponatraemia (<135 mmol/L) was evident pre- and post-stage in n = 8 UER, corresponding to 42% of sampled participants. Pre- and post-stage urine colour, urine osmolality and urine/plasma osmolality ratio increased (p < 0.001) as competition progressed in UER, with no change in CON. Plasma volume and extra-cellular water increased (p < 0.001) 22.8% and 9.2%, respectively, from pre-Stage 1 to 5 in UER, with no change in CON.ConclusionWater intake habits of ultra-runners during MSUM conducted in hot ambient conditions appear to be sufficient to maintain baseline euhydration levels. However, fluid over-consumption behaviours were evident along competition, irrespective of running speed and gender. Normonatraemia was observed in the majority of ultra-runners throughout MSUM, despite sodium ingestion under benchmark recommendations.

Debilitating gastrointestinal symptoms is a common feature of endurance running and may be exacerbated by and/or limit the ability to tolerate carbohydrate intake during exercise. The study aimed to determine whether two weeks of repetitive gut-challenge during running can reduce exercise-associated gastrointestinal symptoms and carbohydrate malabsorption. Endurance runners (n=18) performed an initial gut-challenge trial (GC1) comprising 2-hour running exercise at 60% VO (steady state) while consuming a formulated gel-disk containing 30 g carbohydrates (2:1 glucose-fructose, 10% w/v) every 20 minutes, followed by a 1-hour running effort bout. Gastrointestinal symptoms, feeding tolerance, and breath hydrogen (H ) were determined along the gut-challenge trial. After GC1, participants were randomly assigned to a blinded carbohydrate (CHO, 90 gCHO hour ) or placebo (PLA, 0 gCHO hour ) gut-training group. This comprised of consuming the group-specific feeding intervention during 1-hour running exercise at 60% VO equivalent, daily over a period of two weeks. Participants then repeated the gut-challenge trial (GC2). In GC2, a reduced gut discomfort (P=.012), total (P=.009), upper- (P=.015), and lower-gastrointestinal (P=.008) symptoms, and nausea (P=.05) were observed on CHO, but not PLA. Feeding tolerance did not differ between GC1 and GC2 on CHO and PLA. H peak was attenuated in GC2 (6±3 ppm) compared to GC1 (13±6 ppm) on CHO (P=.004), but not on PLA (GC1 11±7 ppm, and GC2 10±10 ppm). The effort bout distance was greater in GC2 (12.3±1.3 km) compared with GC1 (11.7±1.5 km) on CHO (P=.035) only. Two weeks of repetitive gut-challenge improve gastrointestinal symptoms and reduce carbohydrate malabsorption during endurance running, which may have performance implications.

It is commonly believed that gastrointestinal issues during exercise are exacerbated by hypohydration. This study aimed to determine the effect of exercise-induced hypohydration on gastrointestinal integrity, function, symptoms, and systemic endotoxin and inflammatory profiles. In a randomized crossover design, male endurance runners ( n = 11) performed 2 h of running at 70% of maximum oxygen uptake in 25°C ambient temperature with water provision [euhydration (EuH)] and total water restriction [hypohydration (HypoH)] during running, which accounted for 0.6 ± 0.6% and 3.1 ± 0.7% body mass loss, respectively. Blood and fecal samples were collected before and after exercise. Breath samples (H2 determination) were collected and gastrointestinal symptoms (GIS) recorded before, during, and after exercise. HypoH resulted in a higher, yet insignificant, ∆ preexercise to postexercise plasma cortisol concentration (+286 nmol/l vs. +176 nmol/l; P = 0.098) but significantly higher intestinal fatty acid-binding protein (I-FABP) (+539 pg/ml vs. +371 pg/ml; P = 0.047) concentration compared with EuH. A greater breath H2 response ( P = 0.026) was observed on HypoH (1,188 ppm/3 h, peak +12 ppm) vs. EuH (579 ppm/3 h, peak +6 ppm). Despite greater GIS incidence on HypoH (82%) vs. EuH (64%), GIS severity scores were not significant between trials. Exercise-induced leukocytosis (overall pre- to postexercise: 5.9 × 109/l to 12.1 × 109/l) was similar on both trials. Depressed in vitro neutrophil function was observed during recovery on HypoH (−36%) but not on EUH (+6%). A pre- to postexercise increase ( P < 0.05) was observed for circulating cytokine concentrations but not endotoxin values. Hypohydration during 2 h of running modestly perturbs gastrointestinal integrity and function and increases GIS incidence but does not affect systemic endotoxemia and cytokinemia. NEW & NOTEWORTHY Despite anecdotal beliefs that exercise-induced hypohydration exacerbates perturbations to gastrointestinal status, the present study reports only modest perturbations in gastrointestinal integrity, function, and symptoms compared with euhydration maintenance. Exercise-induced hypohydration does not exacerbate systemic endotoxemia and cytokinemia compared with euhydration maintenance. Programmed water intake to maintain euhydration results in gastrointestinal symptom severity similar to exercise-induced hypohydration. Maintaining euhydration during exertional stress prevents the exercise-associated depression in bacterially stimulated neutrophil function.