Table 5.

Summary of studies included in the systematic review that researched into the effect of carbohydrates (CHO) on gastrointestinal (GI) symptoms during exercise.

Autor	Upper GI Symptoms	Lower GI Symptoms	Conclusions
Ultra-Trail
Lavoué et al., 2020 [3]	8 participants experienced at least one GI (nausea = 4, difficulty swallowing = 3 vomiting = 1)	Diarrhea (N = 2)	The episodes of GI were transient and did not cause any major decreases in performance or dropping out
Wardenaar et al., 2018 [5]	Nausea (N = 1)	Urge to defecate (N = 3) Flatulence (N = 3) Side (N = 1)	Lower amount of GI complaints during the race than the post-race
Wardenaar et al., 2015 [6]	Reflux (16.3%) Heartburn (9.3%) Belching (41.9%) Bloating (16.3%) Stomach cramps (14.0%) Nausea (20.9%)	Intestinal cramp (9.3%) Flatulence (34.9%) Urge to defecate (16.3%) Side ache (11.6%) Abdominal pain (9.3%) Loose stool (4.6%) Diarrhea (2.3%)	Higher nutrient intake, except fiber intake, was in general associated with lower frequency of GI distress
Costa et al., 2014 [8]	65% reporting at least one severe symptom (nausea; GI pain; vomiting; indigestion; bloating; abnormal bowel movements (e.g., urgency to defecate)		No association between GI and energy and CHO intake was evident. A 2·5-fold greater occurrence of Gl symptoms was observed in the fast group vs. slow group
Trail Marathon
Urdampilleta et al., 2020 [2]	3 with flatulence and/ or reflux		Athletes with gut training did not evidence any GI problem
Viribay et al., 2020 [4]	3 with flatulence and/ or reflux		Athletes with gut training did not evidence any GI problem

Upper GI complaints such as: reflux, heartburn, belching, bloating, stomach cramps, vomiting and nausea; lower GI, such as: intestinal cramp, flatulence, urge to defecate, side ache, abdominal pain, loose stool, diarrhea, and intestinal bleeding. Other, dizziness, headache, muscle cramps, urge to urinate.