Search

Utilising metadata from existing exertional and exertional-heat stress studies, the study aimed to determine if the exercise-associated increase in core body temperature can predict the change in exercise-induced gastrointestinal syndrome (EIGS) biomarkers and exercise-associated gastrointestinal symptoms (Ex-GIS). Endurance-trained individuals completed 2h of running exercise in temperate (21.2-30.0°C) to hot (35.0-37.2°C) ambient conditions (n=132 trials). Blood samples were collected pre- and post-exercise to determine the change in gastrointestinal integrity biomarkers and systemic inflammatory cytokines. Physiological and thermoregulatory strain variables were assessed every 10-15min during exercise. The strength of the linear relationship between maximal (M-Tre) and change (Δ Tre) in rectal temperature and EIGS variables was determined via Spearman’s rank correlation coefficients. While the strength of prediction was determined via simple and multiple linear regression analyses dependent on screened EIGS and Ex-GIS confounding factors. Significant positive correlations between Tre maximum (M-Tre) and change (Δ Tre) with I-FABP (rs=0.434, ps=0.305, ps=0.358, ps=0.362, pre and Δ Tre significantly predicted (adjusted R2) magnitude of change in I-FABP (R2(2,123)=0.164, p2(2,119)=0.058, p=0.011; respectively), sCD14 (R2(2,81)=0.249, p2(2,77)=0.214, pre and Δ Tre with plasma concentrations of I-FABP, sCD14, SIR-Profile, and Ex-GIS in response to exercise. M-Tre and Δ Tre can predict the magnitude of these EIGS variables and Ex-GIS in response to exercise.

This review aimed to identify factors associated with (a) physiological responses, (b) gastrointestinal (GI) symptoms, and (c) exercise performance following sodium citrate supplementation. A literature search identified 33 articles. Observations of physiological responses and GI symptoms were categorized by dose (< 500, 500, and > 500 mg/kg body mass [BM]) and by timing of postingestion measurements (in minutes). Exercise performance following sodium citrate supplementation was compared with placebo using statistical significance, percentage change, and effect size. Performance observations were categorized by exercise duration (very short 420 s) and intensity (very high > 100% VO2max and high 90–100% VO2max). Ingestion of 500 mg/kg BM sodium citrate induced blood alkalosis more frequently than 500 mg/kg BM. The GI symptoms were minimized when a 500 mg/kg BM dose was ingested in capsules rather than in solution. Significant improvements in performance following sodium citrate supplementation were reported in all observations of short-duration and very high–intensity exercise with a 500 mg/kg BM dose. However, the efficacy of supplementation for short-duration, high-intensity exercise is less clear, given that only 25% of observations reported significant improvements in performance following sodium citrate supplementation. Based on the current literature, the authors recommend ingestion of 500 mg/kg BM sodium citrate in capsules to induce alkalosis and minimize GI symptoms. Supplementation was of most benefit to performance of short-duration exercise of very high intensity; further investigation is required to determine the importance of ingestion duration and timing.

Objectives The study aimed to examine if the α-diversity and relative abundance of the gastrointestinal bacterial taxa is associated with the response magnitude of markers characteristic of exercise-induced gastrointestinal syndrome in response to exertional-heat stress. Design Cross-sectional. Methods Twenty-two endurance-trained athletes completed 2 h running at 60% V . O2max in hot ambient conditions (35.2 °C, 25% relative humidity). Faecal samples were collected pre-exercise to determine bacterial taxonomy by 16S rRNA amplicon sequencing (Illumina MiSeq platform). Data were processed using the QIIME2 pipeline (v2019.1) establishing taxonomic classification with >95% confidence using SILVA. Pre- and post-exercise blood samples were used to determine plasma I-FABP and cortisol concentrations, and systemic inflammatory response profile. Markers of physiological and thermoregulatory strain, and gastrointestinal symptoms were measured every 10 min during exercise. Associations were determined by partial correlation controlled for body mass variables. Results Positive associations between Tenericutes (r(18) = 0.446, p = 0.049) and Verrucomicrobia (r(18) = 0.450, p = 0.046) phylum, Akkermansiaceae (r(18) = 0.486, p = 0.030) and Ruminococcaceae (r(18) = 0.449, p = 0.047) family and aligned genus groups with I-FABP were observed. Whilst, associations between Faecalibacterium (r(12) = 0.668, p = 0.009) and Ruminoclostridium-9 (r(12) = −0.577, p = 0.031) genus with systemic inflammatory profile were observed. Association between bacterial phyla, family, and genus groups were also observed for gastrointestinal symptoms and markers of thermoregulatory strain (r(18) >0.400, p Conclusions The relative abundance of several commensal bacterial groups showed modest favourable (i.e., low perturbations) or detrimental associations with the magnitude of gastrointestinal integrity perturbations and symptoms, and potentially influences body temperature change, in response to exertional-heat stress.

BackgroundThis study assessed relationships and sex differences between psychological state (recovery, stress, anxiety, and self-confidence) and gastrointestinal symptoms (GIS) prior to and during a 56 km ultramarathon running race and identified predictive factors of race GIS. Forty-four (26 males, 18 females) ultramarathon competitors completed anxiety, recovery, stress and GIS questionnaires for three days prior to the race and immediately pre-race. Race GIS were assessed immediately post-race. Spearman’s rank order, Mann–WhitneyUtests and regression analyses were used to determine correlations and identify sex differences between psychological state and GIS and determine predictors of race GIS.ResultsRace GIS were significantly correlated with recovery (rs = − 0.381,p = 0.011), stress (rs = 0.500,p = 0.001) and anxiety (rs = 0.408,p = 0.006), calculated as the mean of the three days preceding the race and on race morning. The correlation between anxiety and GIS was strongest in the 24 h immediately prior to the race (allrs > 0.400, and allp p p > 0.05), however, females reported greater state anxiety (p = 0.018) and lower self-confidence than males (p = 0.006) over the three days preceding the race and on race morning.ConclusionEndurance athletes that experience GIS during competition should investigate elevated stress and/or anxiety as a potential contributor and identify if management strategies can reduce the occurrence and severity of GIS.

Exercise-induced gastrointestinal syndrome (EIGS) is a common characteristic of exercise. The causes appear to be multifactorial in origin, but stem primarily from splanchnic hypoperfusion and increased sympathetic drive. These primary causes can lead to secondary outcomes that include increased intestinal epithelial injury and gastrointestinal hyperpermeability, systemic endotoxemia, and responsive cytokinemia, and impaired gastrointestinal function (i.e. transit, digestion, and absorption). Impaired gastrointestinal integrity and functional responses may predispose individuals, engaged in strenuous exercise, to gastrointestinal symptoms (GIS), and health complications of clinical significance, both of which may have exercise performance implications. There is a growing body of evidence indicating heat exposure during exercise (i.e. exertional-heat stress) can substantially exacerbate these gastrointestinal perturbations, proportionally to the magnitude of exertional-heat stress, which is of major concern for athletes preparing for and competing in the upcoming 2020 Tokyo Olympic Games. To date, various hydration and nutritional strategies have been explored to prevent or ameliorate exertional-heat stress associated gastrointestinal perturbations. The aims of the current review are to comprehensively explore the impact of exertional-heat stress on markers of EIGS, examine the evidence for the prevention and (or) management of EIGS in relation to exertional-heat stress, and establish best-practice nutritional recommendations for counteracting EIGS and associated GIS in athletes preparing for and competing in Tokyo 2020.

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.

Periodized carbohydrate availability can enhance exercise capacity, but the effects of short-term fat adaptation carbohydrate restoration (FACR) diets on metabolic responses and exercise performance in endurance athletes have not been conclusively determined. This study aimed to investigate the effect of a FACR diet on measures of resting metabolism, exercise metabolism, and exercise performance. Well-trained male runners (n = 8) completed a FACR dietary intervention (five days’ carbohydrate &lt, 20% and fat &gt, 60% energy, plus one-day carbohydrate ≥ 70% energy), and a control high-carbohydrate (HCHO) diet for six days (carbohydrate &gt, 60% energy, fat &lt, 20% energy) in a randomized crossover design. Pre- and post-intervention metabolic measures included resting metabolic rate (RMR), respiratory quotient (RQ), maximum fat oxidation rate during exercise (MFO), and maximum fat oxidation intensity (FATmax). Measures of exercise performance included maximal oxygen uptake (VO2max), running economy (RE), and 5 km running time trial (5 km-TT). In FACR compared with HCHO, there were significant improvements in FATmax (p = 0.006) and RE (p = 0.048). There were no significant differences (p &gt, 0.05) between FACR and HCHO in RMR, RQ, VO2max, or 5 km-TT. Findings suggest that a short-term (six days) FACR diet may facilitate increased fat oxidation and submaximal exercise economy but does not improve 5 km-TT performance.

Objectives The study aimed to determine the effects of temperature of ingested water during exertional-heat stress on gastrointestinal injury, symptoms and systemic inflammatory responses. Design Randomised cross-over study. Methods Twelve endurance runners completed 2 h running at 60% v ˙ O2max in 35 °C ambient temperature on three separate occasions, consuming 250 ± 40 mL water before and every 15 min during running at either 0.4 ± 0.4 °C (COLD), 7.3 ± 0.8 °C (COOL), or 22.1 ± 1.2 °C (TEMP). Rectal temperature and gastrointestinal symptoms were recorded every 10 min during exercise. Blood was collected pre, immediately and 1 h post-exercise to determine plasma intestinal fatty-acid binding protein (I-FABP), cortisol, and inflammatory cytokine concentrations. Results Compared to TEMP, COLD and COOL blunted the rise in rectal temperature (2.0 ± 0.5 °C vs. 1.6 ± 0.4 °C and 1.7 ± 0.4 °C, respectively; trial × time, p = 0.033). I-FABP increased post-exercise (419%, p Conclusions COLD and COOL water ingestion during exertional-heat stress ameliorates thermoregulatory strain compared to TEMP. However, this appears to have no effect on cytokine profile and minimal effect on intestinal epithelial injury and gastrointestinal symptoms.

The study aimed to determine the effects of mild exertional heat stress on intestinal injury, permeability, gastrointestinal symptoms, and systemic endotoxin and cytokine responses. Ten endurance runners completed 2 h of running at 60% V̇O2max in warm (WARM: 30°C) and temperate (TEMP: 22°C) ambient conditions. Rectal temperature (Tre) and gastrointestinal symptoms were recorded every 10 min during exercise. Blood samples were collected pre- and post-exercise, and during recovery to determine plasma intestinal fatty acid-binding protein (I-FABP) and cortisol concentrations, and systemic endotoxin and inflammatory cytokine profiles. Urinary lactulose:L-rhamnose ratio (L/R) was used to measure small intestine permeability. Compared with TEMP, WARM significantly increased Tre from 50 min onwards (38.1±0.3°C vs. 38.4±0.5°C, respectively; p

The study aimed to determine the effects of exertional-heat stress on gastrointestinal integrity, symptoms, systemic endotoxin and inflammatory responses; and assess the relationship between changes in body temperature and gastrointestinal perturbations. Ten endurance runners completed 2 h running at 60% $$\dot {V}$$ O2max in hot (HOT: 35 °C) and temperate (TEMP: 22 °C)-ambient conditions. Rectal temperature (T re) and gastrointestinal symptoms were recorded every 10 min during exercise. Blood samples were collected pre- and post-exercise, and during recovery to determine plasma intestinal fatty acid binding protein (I-FABP), cortisol, bacterial endotoxin and cytokine profile. Calprotectin was determined from pre- and post-exercise faecal samples. Urinary lactulose:l-rhamnose ratio was used to measure intestinal permeability. Compared with TEMP, HOT significantly increased T re (1.4 ± 0.5 vs 2.4 ± 0.8 °C, p

Exertional heat stress (EHS) disturbs the integrity of the gastrointestinal tract leading to endotoxaemia and cytokinaemia, which have symptomatic and health implications. This study aimed to determine the effects of carbohydrate and protein intake during EHS on gastrointestinal integrity, symptoms, and systemic responses. Eleven (male, n = 6; female, n = 5) endurance runners completed 2 h of running at 60% maximal oxygen uptake in 35 °C ambient temperature on 3 occasions in randomised order, consuming water (WATER), 15 g glucose (GLUC), or energy-matched whey protein hydrolysate (WPH) before and every 20 min during EHS. Rectal temperature and gastrointestinal symptoms were recorded every 10 min during EHS. Blood was collected pre- and post-EHS, and during recovery to determine plasma concentrations of intestinal fatty-acid binding protein (I-FABP) as a marker of intestinal epithelial injury, cortisol, endotoxin, and inflammatory cytokines. Urinary lactulose/l-rhamnose ratio was used to measure small intestine permeability. Compared with WATER, GLUC, and WPH ameliorated EHS associated intestinal epithelial injury (I-FABP: 897 ± 478 pg·mL−1 vs. 123 ± 197 pg·mL−1 and 82 ± 156 pg·mL−1, respectively, p < 0.001) and small intestine permeability (lactulose/l-rhamnose ratio: 0.034 ± 0.014 vs. 0.017 ± 0.005 and 0.008 ± 0.002, respectively, p = 0.001). Endotoxaemia was observed post-EHS in all trials (10.2 pg·mL−1, p = 0.001). Post-EHS anti-endotoxin antibodies were higher (p < 0.01) and cortisol and interleukin-6 lower (p < 0.05) on GLUC than WATER only. Total and upper gastrointestinal symptoms were greater on WPH, compared with GLUC and WATER (p < 0.05), in response to EHS. In conclusion, carbohydrate and protein intake during EHS ameliorates intestinal injury and permeability. Carbohydrate also supports endotoxin clearance and reduces stress markers, while protein appears to increase gastrointestinal symptoms, suggesting that carbohydrate is a more appropriate option.

Debilitating gastrointestinal symptoms are 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 h running exercise at 60% VO2max (steady state) whilst consuming a formulated gel-disc containing 30 g carbohydrates (2:1 glucose-fructose, 10% w/v) every 20 min, followed by a 1 h running effort bout. Gastrointestinal symptoms, feeding tolerance, and breath hydrogen (H2) were determined along the gut-challenge trial. After GC1, participants were randomly assigned to a blinded carbohydrate (CHO, 90 gCHO·h−1) or placebo (PLA, 0 gCHO·h−1) gut-training group. This comprised of consuming the group specific feeding intervention during 1 h running exercise at 60% VO2max equivalent, daily over a period of two weeks. Participants then repeated the gut-challenge trial (GC2). In GC2, a reduced gut discomfort (P= 0.012), total (P= 0.009), upper- (P= 0.015) and lower-gastrointestinal (P= 0.008) symptoms, and nausea (P= 0.05) were observed on CHO, but not PLA. Feeding tolerance did not differ between GC1 and GC2 on CHO and PLA. H2 peak was attenuated in GC2 (6 ± 3 ppm) compared to GC1 (13 ± 6 ppm) on CHO (P= 0.004), 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= 0.035) only. Two weeks of repetitive gut-challenge improves gastrointestinal symptoms and reduces carbohydrate malabsorption during endurance running, which may have performance implications. This article is protected by copyright. All rights reserved.

SummaryBackground “Exercise-induced gastrointestinal syndrome” refers to disturbances of gastrointestinal integrity and function that are common features of strenuous exercise. Aim To systematically review the literature to establish the impact of acute exercise on markers of gastrointestinal integrity and function in healthy populations and those with chronic gastrointestinal conditions. Methods Search literature using five databases (PubMed, EBSCO, Web of Science, SPORTSdiscus, and Ovid Medline) to review publications that focused on the impact of acute exercise on markers of gastrointestinal injury, permeability, endotoxaemia, motility and malabsorption in healthy populations and populations with gastrointestinal diseases/disorders. Results As exercise intensity and duration increases, there is considerable evidence for increases in indices of intestinal injury, permeability and endotoxaemia, together with impairment of gastric emptying, slowing of small intestinal transit and malabsorption. The addition of heat stress and running mode appears to exacerbate these markers of gastrointestinal disturbance. Exercise stress of ≥2 hours at 60% VO2max appears to be the threshold whereby significant gastrointestinal perturbations manifest, irrespective of fitness status. Gastrointestinal symptoms, referable to upper- and lower-gastrointestinal tract, are common and a limiting factor in prolonged strenuous exercise. While there is evidence for health benefits of moderate exercise in patients with inflammatory bowel disease or functional gastrointestinal disorders, the safety of more strenuous exercise has not been established. Conclusions Strenuous exercise has a major reversible impact on gastrointestinal integrity and function of healthy populations. The safety and health implications of prolonged strenuous exercise in patients with chronic gastrointestinal diseases/disorders, while hypothetically worrying, has not been elucidated and requires further investigation.

Due to gastrointestinal tract adaptability, the study aimed to determine the impact of gut-training protocol over 2 weeks on gastrointestinal status, blood glucose availability, fuel kinetics, and running performance. Endurance runners (n = 25) performed a gut-challenge trial (GC1), consisting of 2 h running exercise at 60% V̇O2maxwhilst consuming gel-discs containing 30 g carbohydrates (2:1 glucose/fructose, 10% w/v) every 20 min and a 1 h distance test. Participants were then randomly assigned to a carbohydrate gel-disc (CHO-S), carbohydrate food (CHO-F), or placebo (PLA) gut-training group for 2 weeks of repetitive gut-challenge intervention. Participants then repeated a second gut-challenge trial (GC2). Gastrointestinal symptoms reduced in GC2 on CHO-S (60%; p = 0.008) and CHO-F (63%; p = 0.046); reductions were greater than PLA (p < 0.05). H2peak was lower in GC2 on CHO-S (mean (CI): 6 (4–8) ppm) compared with CHO-F (9 (6–12) ppm) and PLA (12 (2–21) ppm) (trial × time: p < 0.001). Blood glucose concentration was higher in GC2 on CHO-S (7.2 (6.3–8.1) mmol·L−1) compared with CHO-F (6.1 (5.7–6.5) mmol·L−1) and PLA (6.2 (4.9–7.5) mmol·L−1) (trial × time: p = 0.015). No difference in oxidation rates, plasma I-FABP, and cortisol concentrations were observed between groups and trials. Distance test improved on CHO-S (5.2%) and CHO-F (4.3%) in GC2, but not on PLA (–2.1%) (trial × time: p = 0.009). Two weeks of gut-training with CHO-S and CHO-F improved gastrointestinal symptoms and running performance compared with PLA. CHO-S also reduced malabsorption and increased blood glucose availability during endurance running compared with PLA.

The study aimed to determine the impact of a dairy milk recovery beverage immediately after endurance exercise on leukocyte trafficking, neutrophil function, and gastrointestinal tolerance markers during recovery. Male runners (N = 11) completed two feeding trials in randomized order, after 2 hr of running at 70%, fluid restricted, in temperate conditions (25 °C, 43% relative humidity). Immediately postexercise, the participants received a chocolate-flavored dairy milk beverage equating to 1.2 g/kg body mass carbohydrate and 0.4 g/kg body mass protein in one trial, and water volume equivalent in another trial. Venous blood and breath samples were collected preexercise, postexercise, and during recovery to determine the leukocyte counts, plasma intestinal fatty acid binding protein, and cortisol concentrations, as well as breath H2. In addition, 1,000 µl of whole blood was incubated with 1 μg/mlEscherichia colilipopolysaccharide for 1 hr at 37 °C to determine the stimulated plasma elastase concentration. Gastrointestinal symptoms and feeding tolerance markers were measured preexercise, every 15 min during exercise, and hourly postexercise for 3 hr. The postexercise leukocyte (mean [95% confidence interval]: 12.7 [11.6, 14.0] × 109/L [main effect of time, MEOT];p 9/L;p p = .012) and cortisol (236 nMol/L; +71%;p = .006) concentrations, were similar throughout recovery for both trials. No significant difference in breath H2and gastrointestinal symptoms was observed between trials. The total (Trial × Time,p = .025) and per cell (Trial × Time,p = .001) bacterially stimulated neutrophil elastase release was greater for the chocolate-flavored dairy milk recovery beverage (+360% and +28%, respectively) in recovery, compared with the water trial (+85% and −38%, respectively). Chocolate-flavored dairy milk recovery beverage consumption immediately after exercise prevents the decrease in neutrophil function during the recovery period, and it does not account for substantial malabsorption or gastrointestinal symptoms over a water volume equivalent.

The world’s ever-growing population presents a major challenge in providing sustainable food options and in reducing pressures on the Earth’s agricultural land and freshwater resources. Current estimates suggest that agriculture contributes ~30% of global greenhouse gas (GHG) emissions. Additionally, there is an increased demand for animal protein, the production of which is particularly polluting. Therefore, the climate-disrupting potential of feeding the planet is likely to substantially worsen in the future. Due to the nutritional value of animal-based protein, it is not a simple solution to recommend a wholesale reduction in production/consumption of animal proteins. Rather, employing strategies which result in the production of low carbon animal protein may be part of the solution to reduce the GHGs associated with our diets without compromising diet quality. We suggest that farmed mussels may present a partial solution to this dilemma. Mussel production has a relatively low GHG production and does not put undue pressure on land or fresh water supplies. By drawing comparisons to other protein sources using the Australian Food and Nutrient Database and other published data, we demonstrate that they are a sustainable source of high-quality protein, long-chain omega-3 fatty acids, phytosterols, and other key micronutrients such as B-12 and iron. The aim of this review is to summarise the current knowledge on the health benefits and potential risks of increasing the consumption of farmed mussels.

Considering the recent growth of exercise gastroenterology research focusing on exercise-induced gastrointestinal syndrome mechanisms, response magnitude, prevention and management strategies, the standardized assessment of gastrointestinal symptoms (GIS) is warranted. The current methodological study aimed to test the reliability of a modified visual analog scale for assessing GIS during exercise, in response to a variety of exertional-stress scenarios, with and without dietary intervention. Recreational endurance runners (n = 31) performed one of the three exercise protocols, which included: 2-hr running at 70% in temperate (24.7 °C) ambient conditions, with fluid restriction; 2-hr running at 60% in hot (35.1 °C) ambient conditions, while consuming chilled water immediately before and every 15 min during exercise; and 2-hr running at 60% in temperate (23.0 °C) ambient conditions, while consuming 30 g/20 min carbohydrate (2∶1 glucose∶fructose, 10% temperate w/v), followed by a 1-hr distance test. GIS was monitored pre-exercise, periodically during exercise, and immediately postexercise. After wash out, participants were retested in mirrored conditions. No significant differences (p > .05) were identified between test–retest using Wilcoxon signed-rank test for all GIS (specific and categorized), within each exercise protocol and the combined protocols. Strong correlations were observed for gut discomfort, total GIS, upper GIS, and nausea (rs = .566 to rs = .686; p rs = .204; p = .232). Cohen’s magnitude of difference was minimal for all GIS (specific δ

To examine if ad libitum drinking will adequately support hydration during exertional heat stress. Ten endurance-trained runners ran for 2 h at 60% of maximum oxygen uptake under different conditions. Participants drank water ad libitum during separate trials at mean ambient temperatures of 22 °C, 30 °C and 35 °C. Participants also completed three trials at a mean ambient temperature of 35 °C while drinking water ad libitum in all trials, and with consumption of programmed glucose or whey protein hydrolysate solutions to maintain euhydration in two of these trials. Heart rate, oxygen uptake, rectal temperature, perceived effort, and thermal sensation were monitored, and nude body mass, hemoglobin, hematocrit, and plasma osmolality were measured before and after exercise. Water and mass balance equations were used to calculate hydration-related variables. Participants adjusted their ad libitum water intake so that the same decrease in body mass (1.1–1.2 kg) and same decrease in body water (0.8–0.9 kg) were observed across the range of ambient temperatures which yielded significant differences (p

This study aimed to determine the influence of biological sex on intestinal injury, permeability, gastrointestinal symptoms, and systemic cytokine profile in response to exertional-heat stress. Male (n= 13) and eumenorrheic female (n= 11) endurance runners completed 2 h running at 60% V̇O

Background: Debilitating 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. Methods: Ad 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. Results: GIS 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. Conclusions: GIS 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.