Letter: low-FODMAP diet for exercise-induced gastrointestinal syndrome-Authors' reply

The effect of rugby training on indirect markers of gut permeability and gut damage in academy level rugby players

Purpose

To assess indirect markers of intestinal endothelial cell damage and permeability in academy rugby players in response to rugby training at the beginning and end of preseason.

Methods

Blood and urinary measures (intestinal fatty acid binding protein and lactulose:rhamnose) as measures of gastrointestinal cell damage and permeability were taken at rest and after a standardised collision-based rugby training session in 19 elite male academy rugby players (age: 20 ± 1 years, backs: 89.3 ± 8.4 kg; forwards: 111.8 ± 7.6 kg) at the start of preseason. A subsample (n = 5) repeated the protocol after six weeks of preseason training. Gastrointestinal symptoms (GIS; range of thirteen standard symptoms), aerobic capacity (30–15 intermittent fitness test), and strength (1 repetition maximum) were also measured.

Results

Following the rugby training session at the start of preseason, there was an increase (median; interquartile range) in intestinal fatty acid binding protein (2140; 1260–2730 to 3245; 1985–5143 pg/ml, p = 0.003) and lactulose:rhamnose (0.31; 0.26–0.34 to 0.97; 0.82–1.07, p < 0.001). After six weeks of preseason training players physical qualities improved, and the same trends in blood and urinary measures were observed within the subsample. Overall, the frequency and severity of GIS were low and not correlated to markers of endothelial damage.

Conclusions

Rugby training resulted in increased intestinal endothelial cell damage and permeability compared to rest. A similar magnitude of effect was observed after six weeks of pre-season training. This was not related to the experience of GIS.

Test-Retest Reliability of a Modified Visual Analog Scale Assessment Tool for Determining Incidence and Severity of Gastrointestinal Symptoms in Response to Exercise Stress

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% V˙O2max in temperate (24.7 °C) ambient conditions, with fluid restriction; 2-hr running at 60% V˙O2max 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% V˙O2max 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 (r_s = .566 to r_s = .686; p < .001), but not for lower GIS (r_s = .204; p = .232). Cohen's magnitude of difference was minimal for all GIS (specific δ < 0.14 and categorized δ < 0.08). The modified visual analog scale for assessing GIS during exercise appears to be a reliable tool for identifying incidence and severity of GIS in cohort populations and is sensitive enough to detect exertional and intervention differences.

Exertional-heat stress-associated gastrointestinal perturbations during Olympic sports: Management strategies for athletes preparing and competing in the 2020 Tokyo Olympic Games

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.

Applying a Low-FODMAP Dietary Intervention to a Female Ultraendurance Runner With Irritable Bowel Syndrome During a Multistage Ultramarathon

Malabsorption of fermentable oligo-, di-, mono-saccharides and polyols (FODMAPs) in response to prolonged exercise may increase incidence of upper and lower gastrointestinal symptoms (GIS), which are known to impair exercise performance. This case study aimed to explore the impact of a low-FODMAP diet on exercise-associated GIS in a female ultraendurance runner diagnosed with irritable bowel syndrome, competing in a 6-day 186.7-km mountainous multistage ultramarathon (MSUM). Irritable bowel syndrome symptom severity score at diagnosis was 410 and following a low-FODMAP diet (3.9 g FODMAPs/day) it reduced to 70. The diet was applied 6 days before (i.e., lead-in diet), and maintained during (5.1 g FODMAPs/day) the MSUM. Nutrition intake was analyzed through dietary analysis software. A validated 100-mm visual analog scale quantified GIS incidence and severity. GIS were modest during the MSUM (overall mean ± SD: bloating 27 ± 5 mm and flatulence 23 ± 8 mm), except severe nausea (67 ± 14 mm) experienced throughout. Total daily energy (11.7 ± 1.6 MJ/day) intake did not meet estimated energy requirements (range: 13.9-17.9 MJ/day). Total daily protein [1.4 ± 0.3 g·kg body weight (BW)^-1·day^-1], carbohydrate (9.1 ± 1.3 g·kg BW^-1·day^-1), fat (1.1 ± 0.2 g·kg BW^-1·day^-1), and water (78.7 ± 6.4 ml·kg BW^-1·day^-1) intakes satisfied current consensus guidelines, except for carbohydrates. Carbohydrate intake during running failed to meet recommendations (43 ± 9 g/hr). The runner successfully implemented a low-FODMAP diet and completed the MSUM with minimal GIS. However, suboptimal energy and carbohydrate intake occurred, potentially exacerbated by nausea associated with running at altitude.

Considerations for ultra-endurance activities: part 1- nutrition

Ultra-endurance activities (≥ 4h) present unique challenges that, beyond fatigue, may be exacerbated by sub-optimal nutrition during periods of increased requirements and compromised gastrointestinal function. The causes of fatigue during ultra-endurance exercise are multi-factorial. However, mechanisms can potentially include central or peripheral fatigue, thermal stress, dehydration, and/or endogenous glycogen store depletion; of which optimising nutrition and hydration can partially attenuate. If exercise duration is long enough (e.g. ≥ 10h) and exercise intensity low enough (e.g. 45-60% of maximal oxygen uptake), it is bio-energetically plausible that ketogenic adaptation may enhance ultra-endurance performance, but this requires scientific substantiation. Conversely, the scientific literature has consistently demonstrated that daily dietary carbohydrates (3-12g/kg/day) and carbohydrate intake (30-110g/h) during ultra-endurance events can enhance performance at individually tolerable intake rates. Considering gastrointestinal symptoms are common in ultra-endurance activities, effective dietary prevention and management strategies may provide functional, histological, systemic, and symptomatic benefits. Taken together, a well-practiced and individualized fuelling approach is required to optimize performance in ultra-endurance events.