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Stephanie K. Gaskell, Rhiannon M.J. Snipe and Ricardo J.S. Costa

Gastrointestinal symptoms (GIS) are a common feature of exercise, with prevalence data suggesting intensity and duration of exercise as major influential factors in the magnitude of GIS incidence and severity ( Costa et al., 2017c ). Consistently, >60% of ultraendurance athletes report GIS during

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Alan J. McCubbin, Anyi Zhu, Stephanie K. Gaskell and Ricardo J.S. Costa

-associated gastrointestinal symptoms (GIS; Jeukendrup, 2014 ). More recently, there has been a focus on additional ingredients in CES to further improve gastric emptying, minimize GIS, and enhance carbohydrate absorption and oxidation during exercise ( Sutehall et al., 2018 ). Through the addition of alginate and pectin

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Charles S. Urwin, Dan B. Dwyer and Amelia J. Carr

Sodium citrate induces alkalosis and can provide a performance benefit in high-intensity exercise. Previous investigations have been inconsistent in the ingestion protocols used, in particular the dose and timing of ingestion before the onset of exercise. The primary aim of the current study was to quantify blood pH, blood bicarbonate concentration and gastrointestinal symptoms after ingestion of three doses of sodium citrate (500 mg⋅kg-1, 700 mg⋅kg-1 and 900 mg⋅kg-1). Thirteen participants completed four experimental sessions, each consisting of a different dose of sodium citrate or a taste-matched placebo solution. Blood pH and blood bicarbonate concentration were measured at 30-min intervals via analysis of capillary blood samples. Gastrointestinal symptoms were also monitored at 30-min intervals. Statistical significance was accepted at a level of p < .05. Both measures of alkalosis were significantly greater after ingestion of sodium citrate compared with placebo (p < .001). No significant differences in alkalosis were found between the three sodium citrate doses (p > .05). Peak alkalosis following sodium citrate ingestion ranged from 180 to 212 min after ingestion. Gastrointestinal symptoms were significantly higher after sodium citrate ingestion compared with placebo (p < .001), while the 900 dose elicited significantly greater gastrointestinal distress than 500 mg⋅kg-1 (p = .004). It is recommended that a dose of 500 mg⋅kg-1 of sodium citrate should be ingested at least 3 hr before exercise, to achieve peak alkalosis and to minimize gastrointestinal symptoms before and during exercise.

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Ricardo J.S. Costa, Vera Camões-Costa, Rhiannon M.J. Snipe, David Dixon, Isabella Russo and Zoya Huschtscha

-debilitating gastrointestinal symptoms (GIS; Costa et al., 2017a ). With this in mind, it has previously been shown that consuming a CHO (1.2 g CHO/kg body mass [BM]) recovery beverage, with or without protein (PRO; 0.4 g PRO/kg BM), from supplement-based ingredients (i.e., maltodextrin and soya PRO) immediately after 2 hr of

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Stephanie K. Gaskell and Ricardo J.S. Costa

population ( Lovell & Ford, 2012 ). IBS has also been reported among exercising populations; including in endurance athletes ( Diduch, 2017 ; Heiman et al., 2008 ). Gastrointestinal symptoms (GIS) experienced by individuals with IBS mimic those commonly reported by non-IBS athletes during and after

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Amelia J. Carr, Gary J. Slater, Christopher J. Gore, Brian Dawson and Louise M. Burke


Sodium bicarbonate (NaHCO3) is often ingested at a dose of 0.3 g/kg body mass (BM), but ingestion protocols are inconsistent in terms of using solution or capsules, ingestion period, combining NaHCO3 with sodium citrate (Na3C6H5O7), and coingested food and fluid.


To quantify the effect of ingesting 0.3 g/kg NaHCO3 on blood pH, [HCO3−], and gastrointestinal (GI) symptoms over the subsequent 3 hr using a range of ingestion protocols and, thus, to determine an optimal protocol.


In a crossover design, 13 physically active subjects undertook 8 NaHCO3 experimental ingestion protocols and 1 placebo protocol. Capillary blood was taken every 30 min and analyzed for pH and [HCO3−]. GI symptoms were quantified every 30 min via questionnaire. Statistics used were pairwise comparisons between protocols; differences were interpreted in relation to smallest worthwhile changes for each variable. A likelihood of >75% was a substantial change.


[HCO3−] and pH were substantially greater than in placebo for all other ingestion protocols at almost all time points. When NaHCO3 was coingested with food, the greatest [HCO3−] (30.9 mmol/kg) and pH (7.49) and lowest incidence of GI symptoms were observed. The greatest incidence of GI side effects was observed 90 min after ingestion of 0.3 g/kg NaHCO3 solution.


The changes in pH and [HCO3−] for the 8 NaHCO3-ingestion protocols were similar, so an optimal protocol cannot be recommended. However, the results suggest that NaHCO3 coingested with a high-carbohydrate meal should be taken 120–150 min before exercise to induce substantial blood alkalosis and reduce GI symptoms.

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Dana Lis, Kiran D.K. Ahuja, Trent Stellingwerff, Cecilia M. Kitic and James Fell

Athletes employ various dietary strategies in attempts to attenuate exercise-induced gastrointestinal (GI) symptoms to ensure optimal performance. This case-study outlines one of these GI-targeted approaches via the implementation of a short-term low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) diet, with the aim to attenuate persistent running specific GI symptoms in a recreationally competitive multisport athlete (male, 86 kg, 57.9 ml·kg·min-1 V02max, 10–15 hr/week training, with no diagnosed GI disorder). Using a single-blinded approach a habitual diet was compared with a 6-day low FODMAP intervention diet (81 ± 5g vs 7.2 ± 5.7g FODMAP s/day) for their effect on GI symptoms and perceptual wellbeing. Training was similar during the habitual and dietary intervention periods. Postexercise (During) GI symptom ratings were recorded immediately following training. Daily GI symptoms and the Daily Analysis of Life Demands for Athletes (DALDA) were recorded at the end of each day. Daily and During GI symptom scores (scale 0–9) ranged from 0–4 during the habitual dietary period while during the low FODMAP dietary period all scores were 0 (no symptoms at all). DALDA scores for worse than normal ranged from 3–10 vs 0–8 in the habitual and low FODMAP dietary periods, respectively, indicating improvement. This intervention was effective for this GI symptom prone athlete; however, randomized-controlled trials are required to assess the suitability of low FODMAP diets for reducing GI distress in other symptomatic athletes.

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Riina A. Kekkonen, Tommi J. Vasankari, Timo Vuorimaa, Tari Haahtela, Ilkka Julkunen and Riitta Korpela

Heavy exercise is associated with an increased risk of upper respiratory tract infections. Strenuous exercise also causes gastrointestinal (GI) symptoms. In previous studies probiotics have reduced respiratory tract infections and GI symptoms in general populations including children, adults, and the elderly. These questions have not been studied in athletes before. The purpose of this study was to investigate the effect of probiotics on the number of healthy days, respiratory infections, and GI-symptom episodes in marathon runners in the summer. Marathon runners (N = 141) were recruited for a randomized, double-blind intervention study during which they received Lactobacillus rhamnosus GG (LGG) or placebo for a 3-mo training period. At the end of the training period the subjects took part in a marathon race, after which they were followed up for 2 wk. The mean number of healthy days was 79.0 in the LGG group and 73.4 in the placebo group (P = 0.82). There were no differences in the number of respiratory infections or GI-symptom episodes. The duration of GI-symptom episodes in the LGG group was 2.9 vs. 4.3 d in the placebo group during the training period (P = 0.35) and 1.0 vs. 2.3 d, respectively, during the 2 wk after the marathon (P = 0.046). LGG had no effect on the incidence of respiratory infections or GI-symptom episodes in marathon runners, but it seemed to shorten the duration of GI-symptom episodes.

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Dana M. Lis, Trent Stellingwerff, Cecilia M. Shing, Kiran D.K. Ahuja and James W. Fell

Adherence to a gluten-free diet (GFD) for nonceliac athletes (NCA) has become increasingly popular despite a paucity of supportive medical or ergogenic evidence. This study aimed to quantify the demographics of NCA and determine associated experiences, perceptions, and sources of information related to GFD. Athletes (n = 910, female = 528, no gender selected = 5) completed a 17-question online survey. Forty-one percent of NCA respondents, including 18-world and/or Olympic medalists, follow a GFD 50–100% of the time (GFD > 50): only 13% for treatment of reported medical conditions with 57% self-diagnosing their gluten sensitivity. The GFD > 50 group characteristics included predominantly endurance sport athletes (70.0%) at the recreationally competitive level (32.3%), between 31 and 40 years of age (29.1%). Those who follow a GFD > 50 reported experiencing, abdominal/gastrointestinal (GI) symptoms alone (16.7%) or in conjunction with two (30.7%) or three (35.7%) additional symptoms (e.g., fatigue) believed to be triggered by gluten. Eighty-four percent of GFD > 50 indicated symptom improvement with gluten-removal. Symptom-based and non-symptom-based self-diagnosed gluten-sensitivity (56.7%) was the primary reason for adopting a GFD. Leading sources of GFD information were online (28.7%), trainer/coach (26.2%) and other athletes (17.4%). Although 5–10% of the general population is estimated to benefit clinically from a GFD a higher prevalence of GFD adherence was found in NCA (41.2%). Prescription of a GFD among many athletes does not result from evidence-based practice suggesting that adoption of a GFD in the majority of cases was not based on medical rationale and may be driven by perception that gluten removal provides health benefits and an ergogenic edge in NCA.

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Dana M. Lis, Daniel Kings and D. Enette Larson-Meyer

, monosaccharides, and polyols (FODMAP) diet is also gaining popularity as a beneficial strategy to reduce commonly occurring exercise-associated gastrointestinal symptoms ( Costa et al., 2017 ). Due to the risks associated with unnecessary dietary restriction, special diets or dietary restraint should be carefully