The influence of exercise intensity and exercise mode on gastrointestinal damage

Strenuous exercise increases gastrointestinal damage, but the dose-response relationship is yet to be elucidated. It is also commonly believed that running causes greater gastrointestinal damage than cycling. Two randomised, crossover studies aimed to 1) quantify gastrointestinal damage with increasing exercise intensity, and 2) determine if running was associated with greater gastrointestinal damage than cycling. Following a maximal oxygen uptake (V̇O_2max) test, participants completed 3 cycling trials at different intensities (60 min at 40%, 60% and 80% V̇O_2max; n = 10 (5 female, 5 male)) (INTENSITY), or 1 running and 1 cycling trial (45 min at 70% V̇O_2max; n = 11 (3 female, 8 male)) (MODE). Venous blood samples were collected pre- and post-exercise to measure gastrointestinal damage via intestinal fatty acid binding protein (I-FABP). In INTENSITY, I-FABP magnitude of change was greater at 80% V̇O_2max than 40% V̇O_2max (p < 0.01). In MODE, I-FABP magnitude of change was greater with cycling (mean (SD)) (84.7 (133.2)% d = 1.07) compared with running (19.3 (33.1)%, d = 0.65) with a moderate effect (d = 0.68, p = 0.024). Rating of perceived exertion (RPE) and heart rate (HR) were higher during cycling (RPE p < 0.0001; HR p < 0.0001) but rectal temperature was not different between modes (p = 0.94). While gastrointestinal damage increases with increasing exercise intensity, running was not associated with greater gastrointestinal damage than cycling. Novelty: A fraction of the anaerobic threshold, rather than a fraction of V̇O_2max, may be more predictive of intensity that results in exercise induced gastrointestinal damage. The mode of exercise may not be as important as intensity for inducing gastrointestinal damage. Improving anaerobic threshold may reduce susceptibility to gastrointestinal damage when exercising at high intensities.

Addition of pectin-alginate to a carbohydrate beverage does not maintain gastrointestinal barrier function during exercise in hot-humid conditions better than carbohydrate ingestion alone

The objective of this study was to compare the effects of consuming a 16% maltodextrin+fructose+pectin-alginate (MAL+FRU+PEC+ALG) drink against a nutrient-matched maltodextrin+fructose (MAL+FRU) drink on enterocyte damage and gastrointestinal permeability after cycling in hot and humid conditions. Fourteen recreational cyclists (7 men) completed 3 experimental trials in a randomized placebo-controlled design. Participants cycled for 90 min (45% maximal aerobic capacity) and completed a 15-min time-trial in hot (32 °C) humid (70% relative humidity) conditions. Every 15 min, cyclists consumed 143 mL of either (i) water; (ii) MAL+FRU+PEC+ALG (90 g·h^-1 CHO/16% w/v); or (iii) a ratio-matched MAL+FRU drink (90 g·h^-1 CHO/16% w/v). Blood was sampled before and after exercise and gastrointestinal (GI) permeability, which was determined by serum measurements of intestinal fatty acid binding protein (I-FABP) and the percent ratio of lactulose (5 g) to rhamnose (2 g) recovered in postexercise urine. Compared with water, I-FABP decreased by 349 ± 67pg·mL^-1 with MAL+FRU+PEC+ALG (p = 0.007) and by 427 ± 56 pg·mL^-1 with MAL+FRU (p = 0.02). GI permeability was reduced in both the MAL+FRU+PEC+ALG (by 0.019 ± 0.01, p = 0.0003) and MAL+FRU (by 0.014 ± 0.01, p = 0.002) conditions relative to water. In conclusion, both CHO beverages attenuated GI barrier damage to a similar extent relative to water. No metabolic, cardiovascular, thermoregulatory, or performance differences were observed between the CHO beverages. Novelty Consumption of multiple-transportable CHO, with or without hydrogel properties, preserves GI barrier integrity and reduces enterocyte damage during prolonged cycling in hot-humid conditions.

Detection and molecular characterisation of Giardia duodenalis, Cryptosporidium spp. and Entamoeba spp. among patients with gastrointestinal symptoms in Gambo Hospital, Oromia Region, southern Ethiopia

OBJECTIVES

To assess the prevalence and genetic diversity of the enteric protozoa species G. duodenalis, Cryptosporidium spp. and Entamoeba histolytica in individuals with gastrointestinal symptoms compatible with infections by these pathogens seeking medical attention in a rural area in southern Ethiopia.

METHODS

A total of 92 stool samples were initially screened by direct microscopy and immunochromatography and further confirmed by molecular methods. G. duodenalis-positive samples were molecularly characterised by multilocus genotyping of the glutamate dehydrogenase and β-giardin genes of the parasite. PCR and DNA sequence analysis of the gene encoding the 60-kDa glycoprotein was used for the subtyping of Cryptosporidium isolates. Detection and differential diagnosis of E. histolytica/dispar were conducted by real-time PCR.

RESULTS

PCR-based prevalences were 10.9% for G. duodenalis, 1.1% for Cryptosporidium spp. and 3.3% for Entamoeba spp. Seven (four novel and three known) subtypes of G. duodenalis assemblage B were identified at the GDH locus and 5 (one novel and four known) at the BG locus. A novel variant of C. hominis subtype IbA9G3 was also identified. Two Entamoeba isolates were assigned to E. dispar and an additional one to E. histolytica.

CONCLUSION

Although preliminary, our results strongly suggest that giardiasis, cryptosporidiosis and amoebiasis represent a significant burden in Ethiopian rural population.