Test Re-Test Reliability of a Modified Visual Analogue 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 standardised assessment of gastrointestinal symptoms (GIS) is warranted. The current methodological study aimed to test the reliability of a modified visual analogue scale (mVAS) 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-three exercise protocols, which included: 2h running at 70% V̇O2max in temperate (24.7°C) ambient conditions, with fluid restriction; 2h running at 60% V̇O2max in hot (35.1°C) ambient conditions, whilst consuming chilled water immediately before and every 15min during exercise; and 2h running at 60% V̇O2max in temperate (23.0°C) ambient conditions, whilst consuming 30g/20min carbohydrate (2:1 glucose-fructose, 10% temperate w/v), followed by a 1h distance-test. GIS was monitored pre-exercise, periodically during exercise, and immediately post-exercise. After washout, participants were re-tested in mirrored conditions. No significant differences (P>0.05) were identified between test-retest using Wilcoxon signed-rank test for all GIS (specific and categorised), within each exercise protocol and combined. Strong correlations were observed for gut discomfort, total-GIS, upper-GIS, and nausea (rs =0.566 to rs =0.686; P< 0.001), but not for lower-GIS (rs =0.204; p=0.232). Cohen's magnitude of difference was minimal for all GIS (specific δ<0.14, categorised δ<0.08). The mVAS 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.