The impact of 48 h high carbohydrate diets with high and low FODMAP content on gastrointestinal status and symptoms in response to endurance exercise, and subsequent endurance performance.

This study investigated the effects of a high carbohydrate diet, with varied fermentable oligo-, di-, and mono-saccharide and polyol (FODMAP) content, before endurance exercise on gastrointestinal integrity, motility, and symptoms; and subsequent exercise performance. Twelve endurance athletes were provided with a 48 h high carbohydrate (mean ± SD: 12.1 ± 1.8 g kg day-1) diet on two separate occasions, composed of high (54.8 ± 10.5 g day-1) and low FODMAP (3.0 ± 0.2 g day-1) content. Thereafter, participants completed a 2 h steady-state running exercise at 60% of V ˙ O 2 max (22.9 ± 1.2 °C, 46.4 ± 7.9% RH), followed by a 1 h distance performance test. Pre-exercise and every 20 min during steady-state exercise, 100 mL maltodextrin (10% w/v) solution was consumed. A 150 mL lactulose (20 g) solution was consumed 30 min into the distance performance test to determine orocecal transit time (OCTT) during exercise. Blood was collected pre- and post exercise to determine gastrointestinal integrity biomarkers (i.e., I-FABP, sCD14, and CRP). Breath hydrogen (H2) and gastrointestinal symptoms (GIS) were determined pre-exercise, every 15 min, during and throughout recovery. No differences in gastrointestinal integrity biomarkers, OCTT, or distance completed were observed between trials. Pre-exercise total-GIS (1.3 ± 2.9 vs. 4.3 ± 4.4), gut discomfort (9.9 ± 8.1 vs. 15.8 ± 9.0), and upper-GIS (2.8 ± 2.6 vs. 5.7 ± 4.8) during exercise were less severe on high carbohydrate low FODMAP (HC-LFOD) versus high carbohydrate high FODMAP (HC-HFOD) (p < 0.05). Gut discomfort (3.4 ± 4.4 vs. 0.2 ± 0.6) and total-GIS (4.9 ± 6.8 vs. 0.2 ± 0.6) were higher during recovery on HC-LFOD versus HC-HFOD (p < 0.05). The FODMAP content of a 48 h high carbohydrate diet does not impact gastrointestinal integrity or motility in response to endurance exercise. However, a high FODMAP content exacerbates GIS before and during exercise, but this does not impact performance outcomes.

Does Age Influence Gastrointestinal Status Responses to Exertional-heat Stress?

This meta-data exploration aimed to determine the impact of exertional-heat stress (EHS) on gastrointestinal status of masters age and young adult endurance athletes. Sixteen MASTERS (mean: 44y) and twenty-one YOUNG (26y) recreational endurance athletes completed 2 h of running at 60% ˙V O2max in 35˚C ambient conditions. Blood samples were collected pre-, immediately and 1 h post-EHS, and analyzed for markers of exercise-induced gastrointestinal syndrome (EIGS). Thermo-physiological measures and gastrointestinal symptoms (GIS) were recorded every 10-20 min during EHS. Peak Δ pre- to post-EHS did not substantially differ (p>0.05) between MASTERS and YOUNG for intestinal epithelial injury [I-FABP: 1652pg/ml vs. 1524pg/ml, respectively], bacterial endotoxic translocation [sCD14: -0.09µg/mL vs. 0.84µg/mL, respectively], lipopolysaccharide-binding protein [LBP: 0.26µg/mL vs. 1.76µg/mL, respectively], and systemic inflammatory response profile (SIR-Profile: 92.0arb.unit vs. 154arb.unit, respectively). A significantly higher peak Δ pre- to post-EHS in endogenous endotoxin anti-body IgM (p=0.042), and pro-inflammatory cytokine IL-1ß (p=0.038), was observed in YOUNG compared to MASTERS. No difference was observed between incidence (81% and 80%, respectively) and severity (summative accumulation: 21 and 30, respectively) of reported GIS during EHS between MASTERS and YOUNG. Pathophysiology of EIGS in response to EHS does not substantially differ with age progression, since masters and younger adult endurance athletes responded comparably.

The Impact of a 24-h Low and High Fermentable Oligo- Di- Mono-Saccharides and Polyol (FODMAP) Diet on Plasma Bacterial Profile in Response to Exertional-Heat Stress.

Exertional-heat stress (EHS) compromises intestinal epithelial integrity, potentially leading to the translocation of pathogenic agents into circulation. This study aimed to explore the impact of EHS on the systemic circulatory bacterial profile and to determine the impact of a short-term low (LFOD) and high (HFOD) fermentable oligo- di- mono-saccharide and polyol dietary intervention before EHS on this profile. Using a double-blind randomized cross-over design, thirteen endurance runners (n = 8 males, n = 5 females), with a history of exercise-associated gastrointestinal symptoms (Ex-GIS), consumed a 24 h LFOD and HFOD before 2 h running at 60% V.O2max in 35.6 °C. Blood and fecal samples were collected pre-EHS to determine plasma microbial DNA concentration, and sample bacteria and short chain fatty acid (SCFA) profiles by fluorometer quantification, 16S rRNA amplicon gene sequencing, and gas chromatography, respectively. Blood samples were also collected post-EHS to determine changes in plasma bacteria. EHS increased plasma microbial DNA similarly in both FODMAP trials (0.019 ng·µL-1 to 0.082 ng·µL-1) (p < 0.01). Similar pre- to post-EHS increases in plasma Proteobacteria (+1.6%) and Firmicutes (+0.6%) phyla relative abundance were observed in both FODMAP trials. This included increases in several Proteobacteria genus (Delftia and Serratia) groups. LFOD presented higher fecal Firmicutes (74%) and lower Bacteroidota (10%) relative abundance pre-EHS, as a result of an increase in Ruminococcaceae and Lachnospiraceae family and respective genus groups, compared with HFOD (64% and 25%, respectively). Pre-EHS plasma total SCFA (p = 0.040) and acetate (p = 0.036) concentrations were higher for HFOD (188 and 178 µmol·L-1, respectively) vs. LFOD (163 and 153 µmol·L-1, respectively). Pre-EHS total fecal SCFA concentration (119 and 74 µmol·g-1; p < 0.001), including acetate (74 and 45 µmol·g-1; p = 0.001), butyrate (22 and 13 µmol·g-1; p = 0.002), and propionate (20 and 13 µmol·g-1; p = 0.011), were higher on HFOD vs LFOD, respectively. EHS causes the translocation of whole bacteria into systemic circulation and alterations to the plasma bacterial profile, but the FODMAP content of a 24 h diet beforehand does not alter this outcome.

Reliability of pathophysiological markers reflective of exercise-induced gastrointestinal syndrome (EIGS) in response to 2-h high-intensity interval exercise: A comprehensive methodological efficacy exploration.

The study aimed to determine the test-retest reliability of exercise-induced gastrointestinal syndrome (EIGS) biomarkers, and assess the association of pre-exercise short chain fatty acid (SCFA) concentration with these biomarkers in response to prolonged strenuous exercise. Thirty-four participants completed 2 h of high-intensity interval training (HIIT) on two separate occasions with at least 5-days washout. Blood samples were collected pre- and post-exercise, and analysed for biomarkers associated with EIGS [i.e., cortisol, intestinal fatty-acid binding protein (I-FABP), sCD14, lipopolysaccharide binding protein (LBP), leukocyte counts, in-vitro neutrophil function, and systemic inflammatory cytokine profile]. Fecal samples were collected pre-exercise on both occasions. In plasma and fecal samples, bacterial DNA concentration was determined by fluorometer quantification, microbial taxonomy by 16S rRNA amplicon sequencing, and SCFA concentration by gas-chromatography. In response to exercise, 2 h of HIIT modestly perturbed biomarkers indicative of EIGS, including inducing bacteremia (i.e., quantity and diversity). Reliability analysis using comparative tests, Cohen's d, two-tailed correlation, and intraclass correlation coefficient (ICC) of resting biomarkers presented good-to-excellent for IL-1ra (r = 0.710, ICC = 0.92), IL-10 (r = 0.665, ICC = 0.73), cortisol (r = 0.870, ICC = 0.87), and LBP (r = 0.813, ICC = 0.76); moderate for total (r = 0.839, ICC = 0.44) and per cell (r = 0.749, ICC = 0.54) bacterially-stimulated elastase release, IL-1ß (r = 0.625, ICC = 0.64), TNF-α (r = 0.523, ICC = 0.56), I-FABP (r = 0.411, ICC = 0.21), and sCD14 (r = 0.409, ICC = 0.38), plus fecal bacterial α-diversity; and poor for leukocyte (r = 0.327, ICC = 0.33) and neutrophil (r = 0.352, ICC = 0.32) counts. In addition, a medium negative correlation was observed between plasma butyrate and I-FABP (r = -0.390). The current data suggest a suite of biomarkers should be used to determine the incidence and severity of EIGS. Moreover, determination of plasma and/or fecal SCFA may provide some insight into the mechanistic aspects of EIGS instigation and magnitude in response to exercise.

Does intestinal epithelial integrity status in response to high-protein dairy milk beverage with or without progressive resistance training impact systemic inflammatory responses in an active aging population?

Increased resting systemic anti-inflammatory responses have previously been reported after a period of progressive resistance training (PRT) with daily consumption of a high-protein dairy beverage. The study aimed to investigate the independent and combined effects of consuming a high protein dairy milk beverage with or without a PRT on markers of intestinal epithelial integrity and selected systemic inflammatory responses in active older (≥50 yrs) adults. Thirty two (males n = 24, females n = 8) active older adults [mean (SD): Age 62 (7) years, weight 74.2 (14.0) kg, height 1.73 (10.0) cm, BMI 24.9 (4.0) kg/m2, and body fat mass: 25.8 (9.1)%)], that reported exercising ≥3/week (211 (91) min/week) were randomly allocated into one of four groups: dairy milk (DM), exercise and dairy milk (EX+DM), exercise alone (EX), and control (CON). Groups with EX underwent 12-weeks whole-body PRT program (x3 sessions/week), groups with DM consumed the beverage twice daily (30g protein/day), and CON was required to carry out their ad libitum dietary and exercise habits. Plasma concentrations of CRP, IL-1ß, IL-1ra, LBP, and sCD14 were determined by ELISA from samples collected at weeks 0, 6, and 12. Data were analyzed (SPSS v25.0) for group and time differences using a two-way repeated-measures ANOVA with post hoc analysis. No significant differences were observed for any of the measured plasma biomarkers. The previously observed increase in anti-inflammatory cytokine response is likely due to a muscular cellular response and not an indication of intestinal epithelial integrity disturbance and/or subsequent translocation of luminal originated pathogenic bacterial compounds.

Assessment of Exercise-Associated Gastrointestinal Perturbations in Research and Practical Settings: Methodological Concerns and Recommendations for Best Practice.

Strenuous exercise is synonymous with disturbing gastrointestinal integrity and function, subsequently prompting systemic immune responses and exercise-associated gastrointestinal symptoms, a condition established as "exercise-induced gastrointestinal syndrome." When exercise stress and aligned exacerbation factors (i.e., extrinsic and intrinsic) are of substantial magnitude, these exercise-associated gastrointestinal perturbations can cause performance decrements and health implications of clinical significance. This potentially explains the exponential growth in exploratory, mechanistic, and interventional research in exercise gastroenterology to understand, accurately measure and interpret, and prevent or attenuate the performance debilitating and health consequences of exercise-induced gastrointestinal syndrome. Considering the recent advancement in exercise gastroenterology research, it has been highlighted that published literature in the area is consistently affected by substantial experimental limitations that may affect the accuracy of translating study outcomes into practical application/s and/or design of future research. This perspective methodological review attempts to highlight these concerns and provides guidance to improve the validity, reliability, and robustness of the next generation of exercise gastroenterology research. These methodological concerns include participant screening and description, exertional and exertional heat stress load, dietary control, hydration status, food and fluid provisions, circadian variation, biological sex differences, comprehensive assessment of established markers of exercise-induced gastrointestinal syndrome, validity of gastrointestinal symptoms assessment tool, and data reporting and presentation. Standardized experimental procedures are needed for the accurate interpretation of research findings, avoiding misinterpreted (e.g., pathological relevance of response magnitude) and overstated conclusions (e.g., clinical and practical relevance of intervention research outcomes), which will support more accurate translation into safe practice guidelines.

Plasma Endogenous Endotoxin Core Antibody Response to Exercise in Endurance Athletes.

The study aimed to investigate the impact of laboratory-controlled exertional and exertional-heat stress on concentrations of plasma endogenous endotoxin core antibody (EndoCAb). Forty-four (males n=26 and females n=18) endurance trained (V̇ O 2max 56.8min/kg/min) participants completed either: P1-2h high intensity interval running in 23°C ambient temperature (Tamb), P2-2h running at 60% V̇ O2max in 35°C Tamb, or P3-3h running at 60% V̇ O2max in 23°C Tamb. Blood samples were collected pre- and post-exercise to determine plasma IgM, IgA, and IgG concentrations. Overall resting pre-exercise levels for plasma Ig were 173MMU/ml, 37AMU/ml, and 79GMU/ml, respectively. Plasma IgM concentration did not substantially change pre- to post-exercise in all protocols, and the magnitude of pre- to post-exercise change for IgM was not different between protocols (p=0.135). Plasma IgA and IgG increased pre- to post-exercise in P2 only (p=0.017 and p=0.016, respectively), but remained within normative range (35-250MU/ml). P2 resulted in greater disturbances to plasma IgA (p=0.058) and IgG (p=0.037), compared with P1 and P3. No substantial differences in pre-exercise and exercise-associated change was observed for EndoCAb between biological sexes. Exertional and exertional-heat stress resulted in modest disturbances to systemic EndoCAb responses, suggesting EndoCAb biomarkers presents a low sensitivity response to controlled-laboratory experimental designs within exercise gastroenterology.

Nutritional outcomes with radiotherapy for head and neck cancer: a before and after comparison of 'best practice guidelines' implementation.

BACKGROUND AND OBJECTIVES: Malnutrition is prevalent amongst people with head and neck cancer treated with radiotherapy and can result in reduced tolerance to treatment and increased hospital admissions. Current bestpractice guidelines recommend weekly dietetic review during radiotherapy and fortnightly review for six weeks following radiotherapy to minimize weight loss. The primary aim of this study was to compare percent weight loss during radiotherapy before and after the implementation of weekly dietetic review. In the post-guideline implementation group we aimed to investigate factors associated with greater weight loss and describe weight changes 4-8 weeks post radiotherapy. METHODS AND STUDY DESIGN: Adults with head and neck cancer who received dietetic input and curative intent radiotherapy were included. Data were collected via retrospective chart audit of records from the Nutrition and Dietetics department. RESULTS: The analysis involved 142 people, 66% (n=94) of whom received dietetic input in the post-guideline implementation period. Mean weight loss was not different between the pre- and post-guideline implementation groups (-5.9±6.34% vs -6.6±5.29%; p=0.477). In the post-guideline implementation group, advanced tumor stage and concurrent chemoradiation were associated with greater percent weight loss (p=0.006 and p<0.001, respectively). Mean weight loss increased by 1.9±4.96%, 4-8 weeks after radiotherapy (p=0.004). CONCLUSIONS: Percent weight loss during radiotherapy was not reduced following the implementation of weekly dietetic review. In the 4-8 weeks following radiotherapy, weight loss increased significantly over that between baseline and end of radiotherapy. Future research should explore and address the reasons why critical weight loss occurs despite improved access to dietetic care.