Hydrogel Carbohydrate-Electrolyte Beverage Does Not Improve Glucose Availability, Substrate Oxidation, Gastrointestinal Symptoms or Exercise Performance, Compared With a Concentration and Nutrient-Matched Placebo

Abstract

The impact of a carbohydrate-electrolyte solution with sodium alginate and pectin for hydrogel formation (CES-HGel), was compared to a standard CES with otherwise matched ingredients (CES-Std), for blood glucose, substrate oxidation, gastrointestinal symptoms (GIS; nausea, belching, bloating, pain, regurgitation, flatulence, urge to defecate, and diarrhea), and exercise performance. Nine trained male endurance runners completed 3 hr of steady-state running (SS) at 60% , consuming 90 g/hr of carbohydrate from CES-HGel or CES-Std (53 g/hr maltodextrin, 37 g/hr fructose, 16% w/v solution) in a randomized crossover design, followed by an incremental time to exhaustion (TTE) test. Blood glucose and substrate oxidation were measured every 30 min during SS and oxidation throughout TTE. Breath hydrogen (H2) was measured every 30 min during exercise and every 15 min for 2 hr postexercise. GIS were recorded every 15 min throughout SS, immediately after and every 15-min post-TTE. No differences in blood glucose (incremental area under the curve [mean ± SD]: CES-HGel 1,100 ± 96 mmol·L−1·150 min−1 and CES-Std 1,076 ± 58 mmol·L−1·150 min−1; p = .266) were observed during SS. There were no differences in substrate oxidation during SS (carbohydrate: p = .650; fat: p = .765) or TTE (carbohydrate: p = .466; fat: p = .633) and no effect of trial on GIS incidence (100% in both trials) or severity (summative rating score: CES-HGel 29.1 ± 32.6 and CES-Std 34.8 ± 34.8; p = .262). Breath hydrogen was not different between trials (p = .347), nor was TTE performance (CES-HGel 722 ± 182 s and CES-Std: 756 ± 187 s; p = .08). In conclusion, sodium alginate and pectin added to a CES consumed during endurance running does not alter the blood glucose responses, carbohydrate malabsorption, substrate oxidation, GIS, or TTE beyond those of a CES with otherwise matched ingredients.

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

“…Our data do not support this proposition. Instead, they support previous observations made in thermoneutral environments during running (McCubbin et al 2019;Barber et al 2020) and cycling (Baur et al 2019;Mears et al 2020a), which reported no differences in blood glucose concentrations, substrate oxidation, or exercise performance between the two drink mixtures.…”

“…In the present study we report high rates of severe GI discomfort (GI scores over 5) in both the MAL+FRU+PEC+ALG (71%) and MAL+FRU (57%) trials relative to water (36%). We can therefore be confident that our protocol induced substantial GI distress during each experimental trial relative to previous investigations using both runners (McCubbin et al 2019;Barber et al 2020) and cyclists (Baur et al 2019;Mears et al 2020a), and increases the likelihood of detecting a difference between CHO drinks. We did note that sensations of gut discomfort were greater following MAL+FRU+PEC+ALG as compared to both the MAL+FRU and WATER.…”

“…It has been speculated that hydrogel formulations increase gastric emptying rates during exercise, enhance absorption of oxidizable CHO, reduce the incidence and severity of gastrointestinal symptoms, and allow provision of CHO in concentrations that far exceed what can typically be tolerated using commercially available sports drinks (Sutehall et al 2018). However, when pectin-alginate CHO drinks have been compared to traditional glucose(polymer) beverages, no differences have been shown in whole body substrate oxidation, blood glucose availability, or GI symptoms during either 90 or 180 minutes of treadmill running at 60% VO2max (McCubbin et al 2019;Barber et al 2020; both 90g . hr -1 CHO, 16% w/v), 120 minutes of cycling at 55% Wmax, (Mears et al 2020, 80g .…”

“…hr -1 , 18% w/v). In light of these findings, it is not surprising that there is no empirical evidence to support additional ergogenic benefits beyond those that are already associated with the ingestion of traditional glucose(polymer)-fructose mixtures during running (McCubbin et al 2019;Barber et al 2020) and cycling exercise (Baur et al, 2019, Mears et al, 2020. It is possible that hydrogel formulations are only ergogenic in certain contexts, such as conditions that are associated with greater GI disturbance or alterations in CHO metabolism.…”

A Hydrogel Drink With High Fructose Content Generates Higher Exogenous Carbohydrate Oxidation and a Reduced Drop in Dental Biofilm pH Compared to Two Other, Commercially Available, Carbohydrate Sports Drinks

“…This finding is in accord with a recent study where ingestion of a 500 mL bolus of a 18% carbohydrate drink containing 0.4 g pectin and 0.6 g of alginate resulted in 1.8 and 2.4 times faster gastric half-emptying time compared to an isoenergetic MD+FRU drink and a glucose+FRU drink, respectively (42). Recent studies have found no difference in total substrate oxidation and blood glucose concentrations (43)(44)(45) or exogenous carbohydrate oxidation (46) with the addition of sodium alginate and pectin in drinks matched for maltodextrin and fructose content during exercise.…”