Investigation of the side pain "stitch" induced by running after fluid ingestion

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.

The effect of transversus abdominis activation on exercise-related transient abdominal pain

OBJECTIVES

Exercise-related transient abdominal pain (ETAP) affects 40-60% of the physically active population, is detrimental to performance but of unknown aetiology. Excessive movement of abdominal peritoneum is one proposed mechanism. Transversus abdominis (TrA) function may play a role reducing in the incidence of Exercise-related transient abdominal pain via the tensioning of the thoracolumbar fascia or increasing intra-abdominal pressure. The aim of this study is to identify any relationship between transversus abdominis function and exercise-related transient abdominal pain, hypothesing that those with stronger transversus abdominis will have lower incidence of exercise-related transient abdominal pain.

DESIGN

Observational study design.

METHODS

Trunk muscle strength was measured clinically using the functional Sahrmann test. Contraction of transversus abdominis was measured by ultrasound imaging of resting muscle size and calculating the change in thickness with a voluntary contraction. Participants completed questionnaires describing any exercise-related transient abdominal pain symptoms, and were divided into four groups dependent upon frequency of any symptoms (never, yearly, monthly and weekly). Between group differences were analysed using analysis of covariance, with Bonferroni correction adjusting for age and training of participants using STATA. Poisson regression determined incident rate ratios for relevant variables.

RESULTS

Data was obtained from fifty runners (28 male, 25.8 ± 7.0 years). Sahrmann test score and frequency of Exercise-related transient abdominal pain were significantly different between groups (p=0.002) with asymptomatic runners having significantly higher Sahrmann test scores (stronger muscles) than weekly and yearly Exercise-related transient abdominal pain groups (p=0.001, p=0.02). There were significant between group differences for resting transversus abdominis thickness (p=0.034) but not for transversus abdominis thickness change (p=0.555).

CONCLUSIONS

Participants who had stronger trunk muscles and larger resting Transversus abdominis size experienced Exercise-related transient abdominal pain less.

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.

Influence of posture and body type on the experience of exercise-related transient abdominal pain

The aim of this study was to evaluate the influence of posture and body type on the experience of exercise-related transient abdominal pain (ETAP). Postural and somatotype assessments were performed on 104 active males and 55 active females aged 18.6+/-0.4 years (mean+/-SD) and were correlated against their self-reported experience of ETAP. Individuals demonstrating kyphosis were more likely to be susceptible to ETAP (p<0.01). Among the individuals susceptible to ETAP, the extent of kyphosis and lordosis influenced the pain severity (p<0.05). There was no relationship between any measure of body type and ETAP. The findings indicate that postural abnormality, particularly in the thoracic region, influences the experience of ETAP.

Spirometry measurements during an episode of exercise-related transient abdominal pain

PURPOSE

To determine whether changes in lung function are associated with exercise-related transient abdominal pain (ETAP).

METHODS

Twenty-eight subjects susceptible to ETAP performed a flow-volume loop before (pre) and after (post) treadmill exercise. Fourteen of the subjects developed symptoms of ETAP during the exercise and completed the flow-volume loop while the pain was present. The remaining 14 subjects reported no symptoms of ETAP.

RESULTS

Forced inspiratory vital capacity was essentially unchanged from pre to post in both groups (ETAP group -0.8% +/- 5.1%, comparison group -0.9% +/- 6.5%). Peak inspiratory-flow rate increased in both the ETAP group (12.4% +/- 16.2%) and the comparison group (17.9% +/- 16.6%), but the difference between groups (-4.6%, standardized effect size [EF] = -0.17) was trivial. Forced expiratory vital capacity decreased by approximately 4% in both groups (ETAP group -3.9% +/- 3.3%, comparison group -4.0% +/- 5.1%). Small differences in the mean change from pre to post between groups were recorded for peak expiratory-flow rate (-7.4%, EF = -0.28) and the forced expiratory volume in the first second of the test (-4.4%, EF = -0.44).

CONCLUSIONS

ETAP does not appear to be associated with reduced inspiratory performance, suggesting that the diaphragm is not implicated directly in the etiology of ETAP. Expiratory power might be slightly reduced during an episode of ETAP, but the magnitude of this effect is unlikely to compromise exercise performance.

EMG activity is not elevated during exercise-related transient abdominal pain

Skeletal muscle cramp has been proposed as the aetiology of exercise-related transient abdominal pain (ETAP). The aim of this study was to determine whether or not localised electromyographic (EMG) activity indicative of skeletal muscle cramp is elevated during ETAP. Surface EMG activity was quantified at the site of ETAP in 14 symptomatic individuals (ETAP group) while the pain was present and after the pain subsided. Additionally, measurements were taken in another 14 subjects (Comparison group) who performed the same experimental procedure but did not experience ETAP. In the ETAP group, localised EMG activity did not increase when the pain was present or decrease when the pain subsided. The level of EMG activity detected while the pain was present was indistinguishable from noise (0.20+/-0.18microV). No difference was observed between the ETAP and Comparison groups in the level of localised EMG activity (p=0.89) at any time. After the pain subsided in the ETAP group, EMG activity was recorded at the site of the pain while the subjects performed a diaphragm-dependent sniff manoeuvre (8.3+/-0.7microV) and a maximum voluntary contraction of the abdominal muscles (17.5+/-0.7microV). It was concluded that ETAP is not associated with elevated EMG activity, suggesting that the pain is not the result of muscle cramping.

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.

Epidemiology of exercise-related transient abdominal pain at the Sydney city to Surf community run

A questionnaire was administered to 848 participants (76% runners, 24% walkers) at the conclusion of the 14 km City to Surf community run in order to investigate their experience of exercise-related transient abdominal pain (ETAP). Twenty-seven percent of respondents reported experiencing ETAP during the event, with the condition reported more frequently (p< 0.01) by runners (30%) than walkers (16%). ETAP was mostly described as well-localised (88%) and of an aching (25%), sharp (22%) or cramping (22%) sensation. The most commonly-reported sites of the pain were the right (46%) and left lumbar (23%) regions of the abdomen. Forty-two percent of the respondents who experienced ETAP reported that the pain was detrimental to their performance. Reports of ETAP decreased with age (r= -0.23, p< 0.01) but were unrelated to gender, body mass index or the time taken to complete the event. Among respondents who ran, those who consumed a large mass of food relative to body weight in the time interval 1-2 hr before the event were more likely to develop symptoms of ETAP (p < 0.05). The nutritional content of the pre-event meal did not influence the experience of ETAP. Sufferers of ETAP were more likely to experience nausea (r = 0.12, p< 0.01) and report shoulder tip pain (r= 0.14, p< 0.01). The results indicate that ETAP is a commonly experienced problem and provide insights into the cause of the complaint.

Exercise related transient abdominal pain

The causes of exercise related transient abdominal pain remain to be elucidated.