Gastrointestinal symptoms in long-distance runners, cyclists, and triathletes: prevalence, medication, and etiology

L-citrulline improves splanchnic perfusion and reduces gut injury during exercise

PURPOSE

Splanchnic hypoperfusion is a physiological phenomenon during strenuous exercise. It has been associated with gastrointestinal symptoms and intestinal injury and may hamper athletic performance. We hypothesized that L-citrulline supplementation improves splanchnic perfusion and decreases intestinal injury by enhancing arginine availability. The aim of this study was to determine the effect of L-citrulline intake on splanchnic perfusion, intestinal injury, and barrier function during exercise.

METHODS

In this randomized, double-blind crossover study, 10 men cycled for 60 min at 70% of their maximum workload after L-citrulline (10 g) or placebo (L-alanine) intake. Splanchnic perfusion was assessed using gastric air tonometry. Sublingual microcirculation was evaluated by sidestream dark field imaging. Plasma amino acid levels and intestinal fatty acid binding protein concentrations, reflecting enterocyte damage, were assessed every 10 min. Urinary excretion of sugar probes was measured to evaluate intestinal permeability changes.

RESULTS

Oral L-citrulline supplementation enhanced plasma citrulline (1840.3 ± 142.3 µM) and arginine levels (238.5 ± 9.1 µM) compared with that in placebo (45.7 ± 4.8 µM and 101.5 ± 6.1 µM, respectively, P < 0.0001), resulting in increased arginine availability. Splanchnic hypoperfusion was prevented during exercise after L-citrulline ingestion (reflected by unaltered gapg-apCO2 levels), whereas gapg-apCO2 increased with placebo treatment (P < 0.01). Accordingly, L-citrulline intake resulted in an increased number of perfused small sublingual vessels compared with that in placebo (7.8 ± 6.0 vs -2.0 ± 2.4, P = 0.06). Furthermore, plasma intestinal fatty acid binding protein levels were attenuated during exercise after L-citrulline supplementation compared with that in placebo (AUC0-60 min, -185% ± 506% vs 1318% ± 553%, P < 0.01). No significant differences were observed for intestinal permeability.

CONCLUSIONS

Pre-exercise L-citrulline intake preserves splanchnic perfusion and attenuates intestinal injury during exercise in athletes compared with placebo, probably by enhancing arginine availability. These results suggest that oral L-citrulline supplementation is a promising intervention to combat splanchnic hypoperfusion-induced intestinal compromise.

Calcium glycerophosphate preserves transepithelial integrity in the Caco-2 model of intestinal transport

AIM: To assess the direct effects of ischemia on intestinal epithelial integrity. Furthermore, clinical efforts at mitigating the effect of hypoperfusion on gut permeability have focused on restoring gut vascular function.

METHODS: We report that, in the Caco-2 cell model of transepithelial transport, calcium glycerophosphate (CGP), an inhibitor of intestinal alkaline phosphatase F3, has a significant effect to preserve transepithelial electrical resistance (TEER) and to attenuate increases in mannitol flux rates during hypoxia or cytokine stimulation.

RESULTS: The effect was observable even at concentrations as low as 1 μmol/L. As celiac disease is also marked by a loss of gut epithelial integrity, the effect of CGP to attenuate the effect of the α-gliadin peptide 31-55 was also examined. In this instance, CGP exerted little effect of preservation of TEER, but significantly attenuated peptide induced increase in mannitol flux.

CONCLUSION: It appears that CGP treatment might synergize with other therapies to preserve gut epithelial integrity.

Microcirculatory effects of L-arginine during acute anaerobic exercise in healthy men: A pilot study

Background/Objective

We hypothesized that L-arginine supplementation increases sublingual capillary perfusion during acute anaerobic exercise.

Methods

In a double-blind randomized study, 20 healthy men were randomly assigned to an L-arginine group or a placebo group. Both groups performed a standard 60-second duration BOSCO jumping test. Before the exercise, immediately after, and 30 minutes after exercise, systemic hemodynamic parameters were recorded. Sublingual evaluation of microcirculation using sidestream dark field (SDF) videomicroscopy was also carried out.

Results

There were no differences in mean arterial blood pressure and cardiac output between the placebo and L-arginine groups immediately after exercise and at 30 minutes after exercise. Both groups had no changes in the microvascular flow index and proportion of perfused vessels of small vessels over the testing period. We observed significantly higher functional capillary density [14.1 (12.5 - 16.0) vs. 11.7 (10.9 - 12.9) 1/mm, p = 0.021] and total vessel density of small vessels [27.8 (24.4 - 29.2) vs. 23.0 (21.6 - 24.2) mm/mm², p = 0.041] in the L-arginine group compared with the placebo group immediately after exercise, but after 30 minutes these differences had disappeared.

Conclusion

Our findings show that supplementation with L-arginine may cause additional effects on the acute anaerobic exercise-induced transient increase in capillary density in the sublingual mucosa of untrained men.

Exercise-related transient abdominal pain (ETAP)

Exercise-related transient abdominal pain (ETAP), commonly referred to as ‘stitch’, is an ailment well known in many sporting activities. It is especially prevalent in activities that involve repetitive torso movement with the torso in an extended position, such as running and horse riding. Approximately 70 % of runners report experiencing the pain in the past year and in a single running event approximately one in five participants can be expected to suffer the condition. ETAP is a localized pain that is most common in the lateral aspects of the mid abdomen along the costal border, although it may occur in any region of the abdomen. It may also be related to shoulder tip pain, which is the referred site from tissue innervated by the phrenic nerve. ETAP tends to be sharp or stabbing when severe, and cramping, aching, or pulling when less intense. The condition is exacerbated by the postprandial state, with hypertonic beverages being particularly provocative. ETAP is most common in the young but is unrelated to sex or body type. Well trained athletes are not immune from the condition, although they may experience it less frequently. Several theories have been presented to explain the mechanism responsible for the pain, including ischemia of the diaphragm; stress on the supportive visceral ligaments that attach the abdominal organs to the diaphragm; gastrointestinal ischemia or distension; cramping of the abdominal musculature; ischemic pain resulting from compression of the celiac artery by the median arcuate ligament; aggravation of the spinal nerves; and irritation of the parietal peritoneum. Of these theories, irritation of the parietal peritoneum best explains the features of ETAP; however, further investigations are required. Strategies for managing the pain are largely anecdotal, especially given that its etiology remains to be fully elucidated. Commonly purported prevention strategies include avoiding large volumes of food and beverages for at least 2 hours prior to exercise, especially hypertonic compounds; improving posture, especially in the thoracic region; and supporting the abdominal organs by improving core strength or wearing a supportive broad belt. Techniques for gaining relief from the pain during an episode are equivocal. This article presents a contemporary understanding of ETAP, which historically has received little research attention but over the past 15 years has been more carefully studied.

Intervention to increase physical activity in irritable bowel syndrome shows long-term positive effects

AIM: To assess the long-term effects of physical activity on irritable bowel syndrome (IBS) symptoms and on quality of life, fatigue, depression and anxiety.

METHODS: Seventy-six patients from a previous randomized controlled interventional study on increased physical activity in IBS were asked to participate in this long-term follow-up study. The included patients attended one visit in which they filled out questionnaires and they underwent a submaximal cycle ergometer test. The primary end point was the change in the IBS Severity Scoring System (IBS-SSS) at baseline, i.e., before the intervention and at follow-up. The secondary endpoints were changes in quality of life, fatigue, depression and anxiety.

RESULTS: A total of 39 [32 women, median age 45 (28-61) years] patients were included in this follow-up. Median follow-up time was 5.2 (range: 3.8-6.2) years. The IBS symptoms were improved compared with baseline [IBS-SSS: 276 (169-360) vs 218 (82-328), P = 0.001]. This was also true for the majority of the dimensions of psychological symptoms such as disease specific quality of life, fatigue, depression and anxiety. The reported time of physical activity during the week before the visit had increased from 3.2 (0.0-10.0) h at baseline to 5.2 (0.0-15.0) h at follow-up, P = 0.019. The most common activities reported were walking, aerobics and cycling. There was no significant difference in the oxygen uptake 31.8 (19.7-45.8) mL per min per kg at baseline vs 34.6 (19.0-54.6) mL/min per kg at follow-up.

CONCLUSION: An intervention to increase physical activity has positive long-term effects on IBS symptoms and psychological symptoms.

Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations

Gastrointestinal problems are common, especially in endurance athletes, and often impair performance or subsequent recovery. Generally, studies suggest that 30-50% of athletes experience such complaints. Most gastrointestinal symptoms during exercise are mild and of no risk to health, but hemorrhagic gastritis, hematochezia, and ischemic bowel can present serious medical challenges. Three main causes of gastrointestinal symptoms have been identified, and these are either physiological, mechanical, or nutritional in nature. During intense exercise, and especially when hypohydrated, mesenteric blood flow is reduced; this is believed to be one of the main contributors to the development of gastrointestinal symptoms. Reduced splanchnic perfusion could result in compromised gut permeability in athletes. However, although evidence exists that this might occur, this has not yet been definitively linked to the prevalence of gastrointestinal symptoms. Nutritional training and appropriate nutrition choices can reduce the risk of gastrointestinal discomfort during exercise by ensuring rapid gastric emptying and the absorption of water and nutrients, and by maintaining adequate perfusion of the splanchnic vasculature. A number of nutritional manipulations have been proposed to minimize gastrointestinal symptoms, including the use of multiple transportable carbohydrates, and potentially the use of nutrients that stimulate the production of nitric oxide in the intestine and thereby improve splanchnic perfusion. However, at this stage, evidence for beneficial effects of such interventions is lacking, and more research needs to be conducted to obtain a better understanding of the etiology of the problems and to improve the recommendations to athletes.

Carbohydrate-dependent, exercise-induced gastrointestinal distress

Gastrointestinal (GI) problems are a common concern of athletes during intense exercise. Ultimately, these symptoms can impair performance and possibly prevent athletes from winning or even finishing a race. The main causes of GI problems during exercise are mechanical, ischemic and nutritional factors. Among the nutritional factors, a high intake of carbohydrate and hyperosmolar solutions increases GI problems. A number of nutritional manipulations have been proposed to minimize gastrointestinal symptoms, including the use of multiple transportable carbohydrates. This type of CHO intake increases the oxidation rates and can prevent the accumulation of carbohydrate in the intestine. Glucose (6%) or glucose plus fructose (8%–10%) beverages are recommended in order to increase CHO intake while avoiding the gastric emptying delay. Training the gut with high intake of CHO may increase absorption capacity and probably prevent GI distress. CHO mouth rinse may be a good strategy to enhance performance without using GI tract in exercises lasting less than an hour. Future strategies should be investigated comparing different CHO types, doses, and concentration in exercises with the same characteristics.

Nutritional indicators for gastrointestinal symptoms in female runners: the 'Marikenloop study'

OBJECTIVES

Among runners the reported prevalence of exercise-induced gastrointestinal (GI) symptoms is high (25%-83%). We aimed to investigate the prevalence of GI symptoms in women during a 5-10 km run in general and to explore the association between nutritional intakes and GI symptoms.

SETTING

As part of the Marikenloop-study (a cohort study to identify predictor variables of running injuries), a cross-sectional questionnaire was distributed in interested runners of the '2013 Marikenloop'.

PARTICIPANTS

433 female runners filled in the questionnaire.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was the frequency of running-related GI symptoms during running in general and during the last (training) run. Furthermore, dietary intake was determined before and during this run. Secondary outcome measures were several demographic and anthropometric variables.

RESULTS

During running in general, 40% of the participants suffered from GI symptoms and during their last run, 49%. The GI symptoms side ache, flatulence, urge to defecate and regurgitation and/or belching were most commonly reported. Lower age (OR=0.98, 95% CI 0.96 to 1.00), minor running experience (OR=3.1, 95% CI 1.7 to 5.7), higher body mass index (OR=1.1, 95% CI 1.0 to 1.2), consuming carbohydrate-containing drinks during running (OR=10.5, 95% CI 1.4 to 80.3) and experiencing GI symptoms during running in general OR=5.0, 95% CI 3.2 to 7.8) significantly contributed to GI symptoms during the last run in the logistic regression analysis. In contrast, time of eating and carbohydrate-containing drinks consumed prior to the run were not related to GI symptoms.

CONCLUSIONS

In conclusion, the current study confirms the high prevalence of GI symptoms in female runners. Several predictor variables contributed to the GI symptoms but more research is needed to specify the effects of prerunning eating and carbohydrate-containing drinks on GI symptoms during running.

TRIAL REGISTRATION NUMBER

Marikenloop study 2013: 50-50310-98-156 (ZonMw).

Coingestion of carbohydrate and protein during training reduces training stress and enhances subsequent exercise performance

Researchers have focused primarily on investigating the effects of coingesting carbohydrate (CHO) and protein (PRO) during recovery and, as such, there is limited research investigating the benefits of CHO+PRO coingestion during exercise for enhancing subsequent exercise performance. The aim of this study was to investigate whether coingestion of CHO+PRO during endurance training would enhance recovery and subsequent exercise performance. Ten well-trained male cyclists (aged 29.7 ± 7.5 years; maximal oxygen uptake, 66.2 ± 6 mL·kg(-1)·min(-1)) took part in a randomized, double-blind, cross-over trial. Each trial consisted of a 2.5-h morning training bout during which the cyclists ingested a CHO+PRO or energy-matched CHO beverage followed by a 4-h recovery period and a subsequent performance time trial (total work, 7 kJ·kg(-1)). Blood was collected before and after exercise. Time-trial performance was 1.8% faster in the CHO+PRO trial compared with the CHO trial (p = 0.149; 95% CI, -13 to 87 s; 75.8% likelihood of benefit). The increase in myoglobin level from before the training bout to after the training bout was lower in the CHO+PRO trial (0.74 nmol·L(-1); 95% CI, 0.3-1.17 nmol·L(-1)) compared with the CHO trial (1.16 nmol·L(-1); 95% CI, 0.6-1.71 nmol·L(-1)) (p = 0.018). Additionally, the decrease in neutrophil count over the recovery period was greater in the CHO+PRO trial (p = 0.034), and heart rate (p < 0.022) and rating of perceived exertion (RPE) (p < 0.01) were lower during training in the CHO+PRO trial compared with the CHO trial. Ingesting PRO, in addition to CHO, during strenuous training lowered exercise stress, as indicated by reduced heart rate, RPE, and muscle damage, when compared with CHO alone. CHO+PRO ingestion during training is also likely to enhance recovery, providing a worthwhile improvement in subsequent cycling time-trial performance.

Ultrasound in sports medicine: relevance of emerging techniques to clinical care of athletes

The applications of ultrasound in managing the clinical care of athletes have been expanding over the past decade. This review provides an analysis of the research that has been published regarding the use of ultrasound in athletes and focuses on how these emerging techniques can impact the clinical management of athletes by sports medicine physicians. Electronic database literature searches were performed using the subject terms 'ultrasound' and 'athletes' from the years 2003 to 2012. The following databases were searched: PubMed, Web of Science, Cochrane Library, CINAHL, and SPORTDiscus™. The search produced 617 articles in total, with a predominance of articles focused on cardiac and musculoskeletal ultrasound. 266 of the studies involved application of ultrasound in evaluating the cardiovascular properties of athletes, and 151 studies involved musculoskeletal ultrasound. Other applications of ultrasound included abdominal, vascular, bone density and volume status. New techniques in echocardiography have made significant contributions to the understanding of the physiological changes that occur in the athlete's heart in response to the haemodynamic stress associated with different types of activity. The likely application of these techniques will be in managing athletes with hypertrophic cardiomyopathy, and the techniques are near ready for application into clinical practice. These techniques are highly specialized, however, and will require referral to dedicated laboratories to influence the clinical management of athletes. Investigation of aortic root pathology and pulmonary vascular haemodynamics are also emerging, but will require additional studies with larger numbers and outcomes analysis to validate their clinical utility. Some of these techniques are relatively simple, and thus hold the potential to enter clinical management in a point-of-care fashion. Musculoskeletal ultrasound has demonstrated a number of diagnostic and therapeutic techniques applicable to pathology of the shoulder, elbow, wrist, hand, hip, knee and ankle. These techniques have been applied mainly to the management of impingement syndromes, tendinopathies and arthritis. Many of these techniques have been validated and have entered clinical practice, while more recently developed techniques (such as dynamic ultrasound and platelet-rich plasma injections) will require further research to verify efficacy. Research in musculoskeletal ultrasound has also been helpful in identifying risk factors for injury and, thus, serving as a focus for developing interventions. Research in abdominal ultrasound has investigated the potential role of ultrasound imaging in assessing splenomegaly in athletes with mononucleosis, in an attempt to inform decisions and policies regarding return to play. Future research will have to demonstrate a reduction in adverse events in order to justify the application of such a technique into policy. The role of ultrasound in assessing groin pain and abdominal pain in ultraendurance athletes has also been investigated, providing promising areas of focus for the development of treatment interventions and physical therapy. Finally, preliminary research has also identified the role of ultrasound in addressing vascular disease, bone density and volume status in athletes. The potential applications of ultrasound in athletes are broad, and continuing research, including larger outcome studies, will be required to establish the clinical utility of these techniques in the care of athletes.

Exercise regulation of intestinal tight junction proteins

Gastrointestinal distress, such as diarrhoea, cramping, vomiting, nausea and gastric pain are common among athletes during training and competition. The mechanisms that cause these symptoms are not fully understood. The stress of heat and oxidative damage during exercise causes disruption to intestinal epithelial cell tight junction proteins resulting in increased permeability to luminal endotoxins. The endotoxin moves into the blood stream leading to a systemic immune response. Tight junction integrity is altered by the phosphoylation state of the proteins occludin and claudins, and may be regulated by the type of exercise performed. Prolonged exercise and high-intensity exercise lead to an increase in key phosphorylation enzymes that ultimately cause tight junction dysfunction, but the mechanisms are different. The purpose of this review is to (1) explain the function and physiology of tight junction regulation, (2) discuss the effects of prolonged and high-intensity exercise on tight junction permeability leading to gastrointestinal distress and (3) review agents that may increase or decrease tight junction integrity during exercise.

Physiology and pathophysiology of splanchnic hypoperfusion and intestinal injury during exercise: strategies for evaluation and prevention

Physical exercise places high demands on the adaptive capacity of the human body. Strenuous physical performance increases the blood supply to active muscles, cardiopulmonary system, and skin to meet the altered demands for oxygen and nutrients. The redistribution of blood flow, necessary for such an increased blood supply to the periphery, significantly reduces blood flow to the gut, leading to hypoperfusion and gastrointestinal (GI) compromise. A compromised GI system can have a negative impact on exercise performance and subsequent postexercise recovery due to abdominal distress and impairments in the uptake of fluid, electrolytes, and nutrients. In addition, strenuous physical exercise leads to loss of epithelial integrity, which may give rise to increased intestinal permeability with bacterial translocation and inflammation. Ultimately, these effects can deteriorate postexercise recovery and disrupt exercise training routine. This review provides an overview on the recent advances in our understanding of GI physiology and pathophysiology in relation to strenuous exercise. Various approaches to determine the impact of exercise on the individual athlete's GI tract are discussed. In addition, we elaborate on several promising components that could be exploited for preventive interventions.

Review article: the pathophysiology and management of gastrointestinal symptoms during physical exercise, and the role of splanchnic blood flow

BACKGROUND

The prevalence of exercise-induced gastrointestinal (GI) symptoms has been reported up to 70%. The pathophysiology largely remains unknown.

AIM

To review the physiological and pathophysiological changes of the GI-tract during physical exercise and the management of the most common gastrointestinal symptoms.

METHODS

Search of the literature published in the English and Dutch languages using the Pubmed database to review the literature that focused on the relation between splanchnic blood flow (SBF), development of ischaemia, postischaemic endotoxinemia and motility.

RESULTS

During physical exercise, the increased activity of the sympathetic nervous system (SNS) redistributes blood flow from the splanchnic organs to the working muscles. With prolonged duration and/or intensity, the SBF may be decreased by 80% or more. Most studies point in the direction of increased SNS-activity as central driving force for reduction in SBF. A severely reduced SBF may frequently cause GI ischaemia. GI-ischaemia combined with reduced vagal activity probably triggers changes in GI-motility and GI absorption derangements. GI-symptoms during physical exercise may be prevented by lowering the exercise intensity, preventing dehydration and avoiding the ingestion of hypertonic fluids.

CONCLUSIONS

Literature on the pathophysiology of exercise-induced GI-symptoms is scarce. Increased sympathetic nervous system activity and decreased splanchnic blood flow during physical exercise seems to be the key factor in the pathogenesis of exercise-induced GI-symptoms, and this should be the target for symptom reduction.

Physical activity benefits and risks on the gastrointestinal system

This review evaluates the current understanding of the benefits and risks of physical activity and exercise on the gastrointestinal system. A significant portion of endurance athletes are affected by gastrointestinal symptoms, but most symptoms are transient and do not have long-term consequences. Conversely, physical activity may have a protective effect on the gastrointestinal system. There is convincing evidence that physical activity reduces the risk of colon cancer. The evidence is less convincing for gastric and pancreatic cancers, gastroesophageal reflux disease, peptic ulcer disease, nonalcoholic fatty liver disease, cholelithiasis, diverticular disease, irritable bowel syndrome, and constipation. Physical activity may reduce the risk of gastrointestinal bleeding and inflammatory bowel disease, although this has not been proven unequivocally. This article provides a critical review of the evidence-based literature concerning exercise and physical activity effects on the gastrointestinal system and provides physicians with a better understanding of the evidence behind exercise prescriptions for patients with gastrointestinal disorders. Well-designed prospective randomized trials evaluating the risks and benefits of exercise and physical activity on gastrointestinal disorders are recommended for future research.

Modeling the association between HR variability and illness in elite swimmers

PURPOSE

To determine whether HR variability (HRV), an indirect measure of autonomic control, is associated with upper respiratory tract and pulmonary infections, muscular affections, and all-type pathologies in elite swimmers.

METHODS

For this study, 7 elite international and 11 national swimmers were observed weekly for 2 yr. The indexes of cardiac autonomic regulation in supine and orthostatic position were assessed as explanatory variables by time domain (SD1, SD2) and spectral analyses (high frequency [HF] = 0.15-0.40 Hz, low frequency [LF] = 0.04-0.15 Hz, and HF/LF ratio) of HRV. Logistic mixed models described the relationship between the explanatory variables and the risk of upper respiratory tract and pulmonary infections, muscular affections, and all-type pathologies.

RESULTS

The risk of all-type pathologies was higher for national swimmers and in winter (P < 0.01). An increase in the parasympathetic indexes (HF, SD1) in the supine position assessed 1 wk earlier was linked to a higher risk of upper respiratory tract and pulmonary infections (P < 0.05) and to a higher risk of muscular affections (increase in HF, P < 0.05). Multivariate analyses showed (1) a higher all-type pathologies risk in winter and for an increase in the total power of HRV associated with a decline SD1 in supine position, (2) a higher all-type pathologies risk in winter associated with a decline in HF assessed 1 wk earlier in orthostatic position, and (3) a higher risk of muscular affections in winter associated with a decrease SD1 and an increase LF in orthostatic position.

CONCLUSIONS

Swimmers' health maintenance requires particular attention when autonomic balance shows a sudden increase in parasympathetic indices in the supine position assessed 1 wk earlier evolving toward sympathetic predominance in supine and orthostatic positions.

Gastrointestinal complaints in runners are not due to small intestinal bacterial overgrowth

Background

Gastrointestinal complaints are common among long distance runners. We hypothesised that small intestinal bacterial overgrowth (SIBO) is present in long distance runners frequently afflicted with gastrointestinal complaints.

Findings

Seven long distance runners (5 female, mean age 29.1 years) with gastrointestinal complaints during and immediately after exercise without known gastrointestinal diseases performed Glucose hydrogen breath tests for detection of SIBO one week after a lactose hydrogen breath test checking for lactose intolerance. The most frequent symptoms were diarrhea (5/7, 71%) and flatulence (6/7, 86%). The study was conducted at a laboratory.

In none of the subjects a pathological hydrogen production was observed after the intake of glucose. Only in one athlete a pathological hydrogen production was measured after the intake of lactose suggesting lactose intolerance.

Conclusions

Gastrointestinal disorders in the examined long distance runners were not associated with small intestinal bacterial overgrowth.

Exercise-induced splanchnic hypoperfusion results in gut dysfunction in healthy men

Background

Splanchnic hypoperfusion is common in various pathophysiological conditions and often considered to lead to gut dysfunction. While it is known that physiological situations such as physical exercise also result in splanchnic hypoperfusion, the consequences of flow redistribution at the expense of abdominal organs remained to be determined. This study focuses on the effects of splanchnic hypoperfusion on the gut, and the relationship between hypoperfusion, intestinal injury and permeability during physical exercise in healthy men.

Methods and Findings

Healthy men cycled for 60 minutes at 70% of maximum workload capacity. Splanchnic hypoperfusion was assessed using gastric tonometry. Blood, sampled every 10 minutes, was analyzed for enterocyte damage parameters (intestinal fatty acid binding protein (I-FABP) and ileal bile acid binding protein (I-BABP)). Changes in intestinal permeability were assessed using sugar probes. Furthermore, liver and renal parameters were assessed. Splanchnic perfusion rapidly decreased during exercise, reflected by increased gap_g-apCO₂ from −0.85±0.15 to 0.85±0.42 kPa (p<0.001). Hypoperfusion increased plasma I-FABP (615±118 vs. 309±46 pg/ml, p<0.001) and I-BABP (14.30±2.20 vs. 5.06±1.27 ng/ml, p<0.001), and hypoperfusion correlated significantly with this small intestinal damage (r_S = 0.59; p<0.001). Last of all, plasma analysis revealed an increase in small intestinal permeability after exercise (p<0.001), which correlated with intestinal injury (r_S = 0.50; p<0.001). Liver parameters, but not renal parameters were elevated.

Conclusions

Exercise-induced splanchnic hypoperfusion results in quantifiable small intestinal injury. Importantly, the extent of intestinal injury correlates with transiently increased small intestinal permeability, indicating gut barrier dysfunction in healthy individuals. These physiological observations increase our knowledge of splanchnic hypoperfusion sequelae, and may help to understand and prevent these phenomena in patients.

Effect of heavy exercise on gastrointestinal transit in endurance athletes

BACKGROUND AND AIMS

Disturbances in transit of the gastrointestinal (GI) tract have been proposed to be involved in the etiology of the GI symptoms in heavy exercise. However, the results are conflicting. In the present study, we investigated the effect of heavy exercise on GI transit in well-trained athletes.

METHODS

Fifteen healthy well-trained athletes underwent measurement of gastric emptying, small bowel transit and colonic transit with radiopaque markers during a resting week and during a week with heavy training. GI symptoms, bowel habits, food intake and exercise performed were registered.

RESULTS

Small bowel transit was accelerated during the training period compared with the resting period (3.7 (2.6-12.3) h vs. 6.9 (4.2-17.2) h, p = 0.04). Segmental colonic transit in the descending colon was significantly accelerated during exercise compared with rest (0.1 (0-0.4) h vs. 0.4 (0.1-0.7) h, p = 0.03). Gastric emptying did not change during exercise compared with resting (2.4 (0.7-4.6) h vs. 1.8 (0.9-3.3) h, p = 0.16). Stool frequency increased significantly during the week with heavy exercise compared with the week without training (1.5 (1.2-1.8) stools/day vs. 1.3 (1.0-1.7) stools/day, p = 0.02). Stool consistency according to Bristol Stool Form Scale tended to be looser during the training period compared with the resting period (4.2 (3.7-4.5) vs. 3.9 (3.0-4.3), p = 0.08).

CONCLUSION

Heavy exercise affects transit in the GI tract, which might be involved in the generation of GI symptoms and altered stool frequency/consistency in endurance athletes.

Physical activity improves symptoms in irritable bowel syndrome: a randomized controlled trial

OBJECTIVES

Physical activity has been shown to be effective in the treatment of conditions, such as fibromyalgia and depression. Although these conditions are associated with irritable bowel syndrome (IBS), no study has assessed the effect of physical activity on gastrointestinal (GI) symptoms in IBS. The aim was to study the effect of physical activity on symptoms in IBS.

METHODS

We randomized 102 patients to a physical activity group and a control group. Patients of the physical activity group were instructed by a physiotherapist to increase their physical activity, and those of the control group were instructed to maintain their lifestyle. The primary end point was to assess the change in the IBS Severity Scoring System (IBS-SSS).

RESULTS

A total of 38 (73.7% women, median age 38.5 (19-65) years) patients in the control group and 37 (75.7% women, median age 36 (18-65) years) patients in the physical activity group completed the study. There was a significant difference in the improvement in the IBS-SSS score between the physical activity group and the control group (-51 (-130 and 49) vs. -5 (-101 and 118), P=0.003). The proportion of patients with increased IBS symptom severity during the study was significantly larger in the control group than in the physical activity group.

CONCLUSIONS

Increased physical activity improves GI symptoms in IBS. Physically active patients with IBS will face less symptom deterioration compared with physically inactive patients. Physical activity should be used as a primary treatment modality in IBS.

The impact of physical exercise on the gastrointestinal tract

PURPOSE OF REVIEW

Physical exercise can be both beneficial and harmful for the gastrointestinal tract in a dose-effect relationship between its intensity and health. Mild-to-moderate intensity exercises play a protective role against colon cancer, diverticular disease, cholelithiasis and constipation, whereas acute strenuous exercise may provoke heartburn, nausea, vomiting, abdominal pain, diarrhea and even gastrointestinal bleeding. This review focuses on mechanisms involved in those symptoms and their associations with type of exercises in humans.

RECENT FINDINGS

One quarter to one half of elite athletes are hampered by the gastrointestinal symptoms that may deter them from participation in training and competitive events. Vigorous exercise-induced gastrointestinal symptoms are often attributed to altered motility, mechanical factor or altered neuroimmunoendocrine secretions. Training, lifestyle modifications, meal composition, adequate hydration and avoidance of excessive use of some medications are the recommendations.

SUMMARY

Strenuous exercise and dehydrated states would be the causes of gastrointestinal symptoms referred by 70% of the athletes. Gut ischemia would be the main cause of nausea, vomiting, abdominal pain and (bloody) diarrhea. The frequency is almost twice as high during running than during other endurance sports as cycling or swimming and 1.5-3.0 times higher in the elite athletes than the recreational exercisers.

Vitamin C and E supplementation prevents mitochondrial damage of ileum myocytes caused by intense and exhaustive exercise training

Intense and exhaustive exercise (IEE) is associated with oxidative stress in skeletal muscle, and we recently reported that intestine is sensitive to IEE. In the present study, we investigated the possible relationship between the effects of IEE on morphology and oxidative markers in the ileum and isolated mitochondria. C57BL/6 mice were ascribed either to a control group comprising two subgroups, one sedentary and another exercised for 10 days (E10), or to a corresponding supplemented control group again comprising two subgroups, one sedentary and another exercised for 10 days (E10-V). The IEE program consisted of a single daily treadmill running session at 85% of V(max), until animal exhaustion. Vitamins C (10 mg/kg) and E (10 mg/kg) were concurrently intraperitoneally administered 2 h before the exercise sessions. IEE was shown to cause 1) impairment of ileum internal membrane mitochondria verified by ultramicrography analysis; 2) increase in ileum carbonyl content (117%) and reduction in antioxidant capacity (36%); 3) increase in mitochondria carbonyl content (38%), increase in the percentage of ruptured mitochondria (25.3%), increase in superoxide dismutase activity (186%), and reduction in citrate synthase activity (40.4%) compared with control animals. Observations in the vitamin-supplemented exercised animals (E10-V) were 1) healthy appearance of myocyte mitochondria; 2) decrease in ileum carbonyl content (66%) and increase in antioxidant capacity (53%); 3) decrease in mitochondria carbonyl content (43%), decrease in the percentage of ruptured mitochondria (30%), slight increase in superoxide dismutase activity (7%), and significant increase in citrate synthase activity (121%) compared with E10 animals. Therefore, the present results strongly corroborate the hypothesis that IEE leads to marked disturbances in intestinal mitochondria, mainly in redox status, and affects whole intestinal redox status.

Prevalence of gastrointestinal complaints in runners competing in a long-distance run: an internet-based observational study in 1281 subjects

OBJECTIVE

To assess the prevalence, risk factors and timing of gastrointestinal (GI) complaints in a large group of runners competing in a long-distance run. GI symptoms indicating GI ischaemia were of specific interest.

MATERIAL AND METHODS

A questionnaire was sent by e-mail to 2076 athletes who had competed in a recreational run and 1281 (62% response rate) were returned. Reported GI complaints were related to variables such as age, gender, distance, fluid and food ingestion and running experience. For statistical analyses, chi(2) tests and logistic regression analyses were used.

RESULTS

The run was completed by 98% of the runners. Three athletes dropped out because of GI complaints, 45% had at least one GI complaint during running, while 11% of the runners suffered from serious GI complaints during the run, the last mentioned being significantly related to runners who were not familiar with fluid ingestion, those of younger age, female gender and those who did not complete the run. Of the runners, 2.7% had complaints during the first 24 h after the run. This was significantly related to female gender and GI complaints during the run.

CONCLUSIONS

The prevalence of GI complaints during and after running was low compared with that reported in other studies, which is partly due to the definition of "symptomatic" used in our study. The risk factors associated with becoming symptomatic were identical to those in other studies. The relationship between complaints during the run and the type of complaints afterwards suggests a role of GI ischaemia in the pathophysiology of running-induced GI symptoms.

Damaging effects of intense repetitive treadmill running on murine intestinal musculature

Several gastrointestinal symptoms associated with prolonged intense exercise (IE) have been reported, although the mechanisms underlying its effects on the intestine remain poorly understood. The aim of the present study was to investigate whether IE may induce oxidative stress in the intestine, as well as its possible relationship with intestinal signaling impairments, leading to contractile disturbances. C57BL/6 mice were submitted to 4 days (EX.4D) and 10 days (EX.10D) of IE. The daily exercise session consisted of a running session until exhaustion, with the treadmill speed set at 85% of each animal's maximum velocity. The decrease in exhaustion time was exponential, and the reduction in the maximum velocity, as assessed by an incremental test, was higher in EX.4D than in EX.10D animals. The ileum mucosa layer was partially destroyed after 4 days of IE, where 37% and 11% muscle layer atrophies were observed in EX.4D and EX.10D animals, respectively. Ileum contractility was significantly impaired in the EX.4D animal group, with reduced efficacy for carbachol, bradykinin, and KCl signaling associated with a decrease in lipid peroxidation and with no alteration of protein oxidation. Intestinal myocytes from EX.10D animals displayed areas containing structurally disorganized mitochondria, which were associated with increased levels of protein oxidation, without alteration of contractility, except for a reduction in the potency of bradykinin signaling. Finally, no clear relationship between ileum contractility and oxidative stress was shown. Together, these results argue in favor of significant functional, biochemical, and morphological disturbances caused by exercise, thus demonstrating that intestinal tissue is very sensitive to exercise.

Efeitos do exercício físico sobre o trato gastrintestinal

O impacto do exercício sobre o trato gastrintestinal (TGI), apesar de pouco investigado, é uma área de grande interesse. O exercício aeróbio intenso e de longa duração pode provocar sintomas gastrintestinais. Estes podem ser divididos em sintomas superiores (vômitos, náuseas e pirose retroesternal - azia) e inferiores (diarréia, cólica abdominal, perda de apetite, sangramento, aceleração dos movimentos intestinais e vontade de defecar). A etiologia desses sintomas durante o exercício é multifatorial e inclui a redução do fluxo sanguíneo intestinal, a liberação de hormônios gastrintestinais, o estresse mecânico sobre o TGI, a desidratação, os fatores psicológicos, a idade, o sexo, a dieta e o nível de treinamento do indivíduo. Por outro lado, o exercício de baixa intensidade tem efeito protetor sobre o TGI, principalmente com relação à predisposição a certas doenças como o câncer de cólon, a diverticulite, a colelitíase e a constipação. Diversos mecanismos são postulados para explicar os efeitos do exercício sobre o TGI, contribuindo para o desenvolvimento de estratégias terapêuticas no tratamento de indivíduos com sintomas e doenças gastrintestinais.

Stitch in the side: causes, workup, and solutions

Side stitch is an acute, localized, sharp, transient pain that occurs during exercise, most often in runners or swimmers, but also in those participating in team sports, and less often in cyclists. The pain is vexing and performance-limiting, but fleeting and benign. Three theories compete to explain it: diaphragmatic ischemia, stress on peritoneal ligaments, and irritation of the parietal peritoneum. The differential diagnosis seems broad, but the classic side stitch is so unique in its features and setting that a reasonable working diagnosis can be made from a careful history and physical examination. Practical tips, although anecdotal, offer lasting solutions.

Training the Gut for Competition

The gut is an important athletic organ because it mediates water and nutrient uptake during exercise. But upper- and lower-gastrointestinal complaints, common to many athletes during exercise, can negatively impact performance, and in severe cases put health at risk. The gut is sensitive to water and nutrient intake during exercise and to hypovolemia, hyperthermia, hypoglycemia, hypoxia, and ischemia. Most gastrointestinal complaints during exercise are mild and of no risk to health, but hemorrhagic gastritis, hematochezia, and ischemic bowel can present medical challenges. Proper training and nutrition minimize the risk of gastrointestinal discomfort during exercise by assuring rapid gastric emptying and absorption of water and nutrients and by maintaining adequate perfusion of the splanchnic vasculature.

Medical Coverage of Cycling Events

Medical coverage of recreational and competitive cycling events requires significant planning and cooperation among the race and medical directors, race officials, and local emergency medical services. The medical team should be proficient in treating minor and self-limiting injuries such as abrasions and minor trauma. The medical team should also have contingency plans for medical emergencies, such as cardiac events and major trauma, that ensure rapid stabilization and transport of the athlete to the appropriate medical facility. Stationary and mobile medical teams may be necessary for proper coverage of the event. Event day communication systems between individual medical staff as well as race officials and local emergency medical services is important to the success of the event.

Proton pump inhibition prevents gastrointestinal bleeding in ultramarathon runners: a randomised, double blinded, placebo controlled study

BACKGROUND

Ultra-endurance running is emerging as a popular sport in Western industrialised countries. Gastrointestinal bleeding has been reported to be an adverse effect in these runners.

OBJECTIVE

To see if the oral administration of a proton pump inhibitor would reduce the incidence of gastrointestinal bleeding in an ultramarathon.

METHODS

In a randomised, double blinded, placebo controlled study, a prophylactic regimen of three days of an oral proton pump inhibitor (pantoprazole 20 mg) was tested in healthy athletes participating in the Spartathlon ultramarathon. The incidence of gastrointestinal bleeding was assessed by a stool guaiac test.

RESULTS

Results were obtained for 70 healthy volunteers. The data for 20 of 35 runners in the intervention group and 17 of 35 runners in the placebo group were entered into the final analysis. At the end of the ultramarathon, two subjects in the intervention group and 12 in the placebo group had positive stool guaiac tests (risk difference 0.86; 95% confidence interval 0.45 to 0.96; p = 0.001).

CONCLUSION

A short prophylactic regimen of oral proton pump inhibition can successfully decrease the incidence of gastrointestinal bleeding in participants in an ultramarathon.

Training Room Management of Medical Conditions: Sports Gastroenterology

Gastrointestinal (GI) illnesses are common in athletes. Various causes include adverse physiologic adaptations of the gut during exercise; excess ingestion of carbohydrate drinks, alcohol, and anti-inflammatory medications; emotional stressors; exposure to pathogens in closed environments and during travel; trauma; and abdominal wall pressure overload. Unfortunately, evidence-based management of GI illnesses in athletes is limited because most studies have compared various GI illnesses between different sports, rather than comparing athletes to nonathletes. This article reviews the evidence that is available specifically relating to etiology, pathophysiology, clinical presentation, relevant differential diagnoses, acute management, and recommendations for specialist consultation of various GI illnesses in the training-room setting.

Gastrointestinal profile of symptomatic athletes at rest and during physical exercise

Some athletes suffer from exercise-induced gastrointestinal (GI) disturbances. We developed a profile of GI parameters in 10 symptomatic and 10 asymptomatic athletes both at rest and during exercise. Exercise included 90 min of cycling and running at 70% of maximal power. We measured oesophageal motility, gastro-oesophageal reflux, gastric emptying, orocaecal transit time (OCTT), intestinal permeability and intestinal glucose absorption. During cycling the number and duration of refluxes were increased, whereas gastric emptying showed no differences between rest, cycling and running. The OCTT was increased in the running trial, compared to rest (P=0.005). Also, intestinal permeability was higher in the running trial, compared to rest (P=0.008). There were no differences in intestinal glucose absorption between rest and exercise. Compared with asymptomatic athletes the symptomatic subjects had a higher intestinal permeability (P=0.001), more reflux episodes (P=0.03) and a longer duration of reflux (P<0.05) during cycling. No differences were observed at rest. In conclusion, there is no difference in GI profile between symptomatic and asymptomatic athletes at rest. During exercise, symptomatic subjects have a longer OCTT and a higher intestinal permeability, which is more pronounced during running than during cycling.

Exercise and gastrointestinal function and disease: an evidence-based review of risks and benefits

BACKGROUND & AIMS

Exercise is beneficial to health because it reduces the risk of cardiovascular and endocrine diseases, improves bone and muscle conditioning, and lessens anxiety and depression. However, the impact of exercise on the gastrointestinal system has been conflicting. This systematic literature review evaluates the effect of the different modes and intensity levels of exercise on gastrointestinal function and disease using an evidence-based approach. Although more applicable to trained athletes and individuals who are highly active and, as such, at risk to experience the side-effects of exercise, an effort was made to state the level or degree of exercise or the lack of such evidence.

RESULTS

Light and moderate exercise is well tolerated and can benefit patients with inflammatory bowel disease and liver disease. Physical activity can also improve gastric emptying and lower the relative risk of colon cancer in most populations. Severe, exhaustive exercise, however, inhibits gastric emptying, interferes with gastrointestinal absorption, and causes many gastrointestinal symptoms, most notably gastrointestinal bleeding.

CONCLUSIONS

This knowledge will enable physicians to prescribe physical exercise in health and disease and to better manage patients with exercise-related gastrointestinal disorders. Our understanding of exercise and its gastrointestinal manifestations as well as risks and benefits warrants further investigation.

Physical activity and the gastrointestinal tract

Physical exercise is probably both beneficial and harmful for the gastrointestinal tract, depending partly on the training intensity. On the one hand, gastrointestinal symptoms such as heartburn, chest pain, nausea, vomiting, abdominal cramps, side ache and diarrhoea are common during heavy exercise. On the other hand, physical activity seems to protect from colon cancer, cholelithiasis and diverticular disease. Constipation has been shown to be related to inactivity. Despite this, no overwhelming evidence exists for a positive effect of physical exercise as a treatment option for chronic constipation. The reasons behind these somewhat discrepant effects are not understood fully. Altered gastrointestinal blood flow, effects on gastrointestinal motor function, neuroendocrine changes and mechanical effects are probably involved. Conflicting results exist regarding the effects of physical activity on gastrointestinal motility. Modern technologies now make motility studies in various parts of the gastrointestinal tract possible. More studies are needed to understand better the effects of physical exercise on the gastrointestinal tract. In particular, the relationship between the training intensity and duration and positive and negative alterations in gastrointestinal physiology needs to be addressed further.

Duodenal motility during a run-bike-run protocol: the effect of a sports drink

OBJECTIVE

To examine the effect of a sports drink during strenuous exercise on duodenal motility and gastrointestinal symptoms.

METHODS

In a cross-over design, seven male triathletes performed two 170-min run-bike-run tests at about 70% peak oxygen uptake (O(2peak)), with either a 7% carbohydrate (CHO) sports drink or tap water. Antroduodenal motility (phase III of the migrating motor complex; MMC) was measured with an ambulant manometry system. The effect of the two exercise trials on the first appearance of the MMC was assessed in the postprandial period.

RESULTS

Exercise heart rate, percentage O(2peak) and loss of body mass did not differ significantly between the two trials. After the start of the exercise, the expected time before the first phase III occurrence, based on the actual energy intake of the last meal in the morning before exercise (1048 +/- 294 kcal), a fixed gastric emptying rate and a lag phase for solid food, was 183 +/- 113 min (mean +/- standard deviation [SD]). The real time period between the start of the exercise with CHO and the first phase III was 63 +/- 61 min, which was significantly shorter than that observed with tap water (152 +/- 59 min). Both real time periods were shorter than the expected time period of 183 +/- 113 min (P < 0.05). During exercise, the number of subjects with a phase III was higher with CHO than with tap water (n =6 v. n =1; P < 0.05). Also, the median number of phases III per hour with CHO was higher than with tap water (0.4 v. 0.0; P < 0.05). During cycling, significantly more phases III per hour (0.9) were measured than during running (0.2). All subjects reported one or more gastrointestinal symptoms during exercise, however, without a clear association with the mode of exercise or supplementation.

CONCLUSIONS

Prolonged exercise results in gastrointestinal symptoms and a significant interruption of postprandial motility. Only the latter phenomenon depends on the mode of exercise and supplementation.