H. P. F. Peters

Potential benefits and hazards of physical activity and exercise on the gastrointestinal tract

This review describes the current state of knowledge on the hazards of exercise and the potential benefits of physical activity on the gastrointestinal tract. In particular, acute strenuous exercise may provoke gastrointestinal symptoms such as heartburn or diarrhoea. A substantial part (20–50%) of endurance athletes are hampered by these symptoms which may deter them from participation in training and competitive events. Nevertheless, these acute symptoms are transient and do not hamper the athletes health in the long term. The only exception is repeated gastrointestinal bleeding during training and competition, which in the long term may occasionally lead to iron deficiency and anaemia. In contrast, repetitive exercise periods at a relatively low intensity may have protective effects on the gastrointestinal tract. There is strong evidence that physical activity reduces the risk of colon cancer by up to 50%. Less convincing evidence exists for cholelithiasis and constipation. Physical activity may reduce the risk of diverticulosis, gastrointestinal haemorrhage, and inflammatory bowel disease although this cannot be substantiated firmly. Up to now, underlying mechanisms are poorly understood although decreased gastrointestinal blood flow, neuro-immuno-endocrine alterations, increased gastrointestinal motility, and mechanical bouncing during exercise are postulated. Future research on exercise associated digestive processes should give more insight into the relationship between physical activity and the function of the gastrointestinal tract.

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

ObjectiveThe aim of this study was to determine the prevalence of exercise-related gastrointestinal (GI) symptoms and the use of medication for these symptoms among long-distance runners, cyclists, and triathletes, and to determine the relationship of different variables to GI symptoms.MethodsA mail questionnaire covering the preceding 12 months was sent to 606 well-trained endurance type athletes: 199 runners (114 men and 85 women), 197 cyclists (98 men and 99 women), and 210 triathletes (110 men and 100 women) and sent back by 93%, 88%, and 71% of these groups, respectively. Symptoms were evaluated with respect to the upper (nausea, vomiting, belching, heartburn, chest pain) or lower part of the GI tract (bloating, GI cramps, side ache, urge to defecate, defecation, diarrhea). For statistical analysis, Mann-Whitney U test, Fisher exact test, or Student t test were used.ResultsRunners experienced more lower (prevalence 71%) than upper (36%) GI symptoms during exercise. Cyclists experienced both upper (67%) and lower (64%) symptoms. Triathletes experienced during cycling both upper (52%) and lower (45%) symptoms, and during running more lower (79%) than upper (54%) symptoms. Bloating, diarrhea, and flatulence occurred more at rest than during exercise among all subjects. In general, exercise-related GI symptoms were significantly related to the occurrence of GI symptoms during nonexercise periods, age, gender, diet, and years of training. The prevalence of medication for exercise-related GI symptoms was 5%, 6%, and 3% for runners, cyclists, and triathletes, respectively.ConclusionsLong-distance running is mainly associated with lower GI symptoms, whereas cycling is associated with both upper and lower symptoms. Triathletes confirm this pattern during cycling and running. The prevalence of medication for exercise-related GI symptoms is lower in the Netherlands in comparison with other countries, in which a prevalence of 10–18% was reported. More research on the possible predisposition of athletes for GI symptoms during exercise is needed.

Effects of regular physical activity on defecation pattern in middle-aged patients complaining of chronic constipation

Objective . It is not well known whether physical activity (PA) is useful in the management of patients complaining of constipation. The aim of this study was to test the influence of regular PA on colonic transit time and defecation in middle-aged inactive patients suffering from chronic idiopathic constipation. Material and methods . Forty-three subjects (>45 years) were randomly divided into group A (n=18, 16 F, 2 M) and group B (n=25, 20 F, 5 M). Group A subjects maintained their normal lifestyle during 12 weeks, followed by a 12-week PA programme. Group B performed a 12-week PA programme after randomization. PA comprised 30 min of brisk walking and a daily 11-min home-based programme. Both groups received dietary advice. Colonic transit time was measured using a radiographic multiple marker single film technique. Results . Despite dietary advice, mean fibre and fluid intake did not change. In group B a significant reduction in 3 out of 4 of the Rome I criteria for constipation was observed, i.e. percentage of incomplete defecations, percentage of defecations requiring straining and percentage of hard stools (p<0.05). As a consequence, the number of fulfilled Rome criteria for constipation decreased (2.7 to 1.7; p<0.05). Furthermore, the rectosigmoid and total colonic transit time decreased (17.5 to 9.6 h and 79.2 to 58.4 h, respectively; p<0.05). After PA the number of fulfilled Rome criteria also decreased in group A (2.6 to 1.7; p<0.05). Conclusions . In middle-aged inactive subjects with symptoms of chronic constipation, it is advisable to promote regular physical activity since it improves both the defecation pattern and rectosigmoid or total colonic transit time.

Gastrointestinal problems as a function of carbohydrate supplements and mode of exercise.

The aim of the study was to examine prevalence and duration/seriousness of gastrointestinal (GI) problems as a function of carbohydrate-rich (CHO) supplements and mode of exercise. The relationship between GI problems and a variety of physiological and personal factors (age, exercise experience) was also examined. Thirty-two male tri-athletes performed three experimental trials at 1-wk intervals, each trial on a different supplement: a conventional, semisolid supplement (S; 1.2 g CHO, 0.1 g protein, and 0.02 g fat.kg BW-1 x h-1); an almost isocaloric fluid supplement (F; 1.3 g CHO.kg BW-1 x h-1, no fat, no protein); and a fluid placebo (P). The 3 h of exercise started at 75% VO2max and consisted of alternately cycling (bouts 1 and 3) and running (bouts 2 and 4). GI symptoms were monitored by a questionnaire. Analysis of variance revealed that nausea lasted longer with P as compared with S (P < 0.05). Bloating lasted longer during bout 3 with P as compared with F and S (P < 0.05). Accounting for confounding factors, most GI symptoms occurred more frequently and lasted longer during running than during cycling. Multiple regression analysis revealed significant relationships between nausea and urge to defecate, between an urge to defecate, GI cramps and flatulence, and between belching and side ache. From all other factors energy depletion, CHO malabsorption, exercise intensity, exercise experience, and age were significantly related to GI symptoms during the exercise.

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 (O2peak), 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 O2peak 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.

Hydrogen breath test as a simple noninvasive method for evaluation of carbohydrate malabsorption during exercise

The aim of this study was to examine hydrogen (H2) production with the hydrogen breath test (HBT) after ingesting primarily digestible carbohydrate (CHO) during 3 h of 75% maximal oxygen consumption exercise. This was done to indicate CHO overflow in the colon which may occur when gastric emptying, intestinal transit and CHO absorption are not matched and CHO accumulates in the colon where it is subject to bacterial degradation. Further, this study was designed to assess breath H2 production as a function of the type of CHO ingested and the type of exercise. A group of 32 male triathletes performed three exercise trials at 1-week intervals with either a semi-solid (S) intake, an equal energy fluid intake (F) or a fluid placebo (P). Each trial consisted of cycling (sessions 1 and 3) and running (sessions 2 and 4). The mixed-expired H2 concentrations in the resting and “recovery” periods (5 min after each session) did not change significantly in. time and did not differ among intakes. There were also no significant differences in H2 concentrations between resting and “recovery” conditions. During exercise, H2 concentrations decreased three to six-fold in comparison to resting and recovery levels and differed among intakes (ANOVA;P < 0.05). The H2 on concentrations were almost continuously lower with P than with F and S. The H2 concentrations were significantly higher during running than during cycling. During exercise, we found that CHO overflow could be compared among intakes and between exercise types by using the HBT, provided the influence of other factors on H2 excretion — ventilation and intestinal blood flow — was similar for each condition.