HYDROGEN BREATH TEST AS A SIMPLE NONINVASIVE METHOD FOR EVALUATION OFCARBOHYDRATE MALABSORPTION DURING EXERCISE

The aim of this study was to examine hydrogen (H-2) production with th e hydrogen breath test (HBT) after ingesting primarily digestible carb ohydrate (CHO) during 3 h of 75% maximal oxygen consumption exercise. This was done to indicate CHO overflow in the colon which may occur wh en gastric emptying, intestinal transit and CHO absorption are not mat ched and CHO accumulates in the colon where it is subject to bacterial degradation. Further, this study was designed to assess breath H-2 pr oduction as a function of the type of CHO ingested and the type of exe rcise. A group of 32 male triathletes performed three exercise trials at 1-week intervals with either a semisolid (S) intake, an equal energ y fluid intake (F) or a fluid placebo (P). Each trial consisted of cyc ling (sessions 1 and 3) and running (sessions 2 and 4). The mixed-expi red H-2 concentrations in the resting and ''recovery'' periods (5 min after each session) did not change significantly in time and did not d iffer among intakes. There were also no significant differences in H-2 concentrations between resting and ''recovery'' conditions. During ex ercise, H-2 concentrations decreased three to six-fold in comparison t o resting and recovery levels and differed among intakes (ANOVA; P < 0 .05). The H-2 concentrations were almost continuously lower with P tha n with F and S. The H-2 concentrations were significantly higher durin g running than during cycling. During exercise, we found that CHO over flow could be compared among intakes and between exercise types by usi ng the HBT, provided the influence of other factors on H-2 excretion - ventilation and intestinal blood flow - was similar for each conditio n.