CHO Condition Research Articles

Responses to Exercise with Low Carbohydrate Availability on Muscle Glycogen and Cell Signaling: A Systematic Review and Meta-analysis.

The growing interest in how exercise and carbohydrate (CHO) restriction may modify molecular responses that promote endurance adaptations has led to many interesting controversies. We conducted a systematic review and a meta-analysis regarding the effect of low-carbohydrate availability (LOW) pre-, during, or post-exercise, on the mRNA content of commonly measured genes involved in mitochondrial biogenesis (PGC-1α, TFAM mRNA) and metabolism (PDK4, UCP3 and GLUT4 mRNA), and on muscle glycogen levels, compared with a high-CHO (CON) condition. MEDLINE, Scopus, and Web of Science databases were searched following the PRISMA 2020 guidelines (with an end date of November 2023). In total, 19 randomized-controlled studies were considered for inclusion. We evaluated the methodological quality of all studies using the Cochrane Risk of Bias tool for randomized clinical studies. A meta-analysis was performed using a random effects model to calculate the standardized mean difference (SMD), estimated by Hedges' g, and 95% confidence intervals (CIs). The LOW condition was associated with an increased mRNA content of several genes during the early recovery period post-exercise, such as PDK4 (SMD 1.61; 95% CI 0.80-2.42), GLUT4 (SMD 1.38; 95% CI 0.46-2.30), and UCP3 (SMD 2.05; 95% CI 0.40-3.69). However, overall, there was no significant effect on the mRNA content of PGC-1α or TFAM. Finally, CHO restriction and exercise significantly reduced muscle glycogen levels (SMD 3.69; 95% CI 2.82-5.09). A meta-analysis of subgroups from studies with a difference in muscle glycogen concentration of > 200mmolkgdw-1 between the LOW and CON conditions showed an increase in exercise-induced PGC-1α mRNA (SMD 2.08; 95% CI 0.64-3.52; p = 0.005; I2 = 75%) and a greater effect in PDK4 and GLUT4 mRNA. The meta-analysis results show that CHO restriction was associated with an increase in the exercise-induced mRNA content of PDK4, UCP3, and GLUT4, but not the exercise-induced mRNA content of PGC-1ɑ and TFAM. However, when there were substantial differences in glycogen depletion between CON and LOW CHO conditions (> 200mmolkgdw-1), there was a greater effect of CHO restriction on the exercise-induced mRNA content of metabolic genes, and an increase in exercise-induced PGC-1α mRNA.

In Vitro Fermentation of Animal and Plant Protein Isolates by the Human Gut Microbiota Under High and Low Carbohydrate Conditions.

There is a lack of research comparing how different protein isolates influence the microbiome, especially when carbohydrate (CHO) availability is varied. The objective is to determine changes in gut microbiota composition and function during fermentation of digested protein isolates under high and low CHO conditions. Protein isolates from beef, egg white, milk, pea, and soy are subjected to in vitro digestion and fermentation with human fecal microbiota. Under low CHO conditions, the microbiota is primarily proteolytic with decreased concentrations of peptides and increased variance among microbial taxa and production of ammonia and branched chain fatty acids by the microbiota. Milk protein not only results in the highest production of butyrate and p-hydroxyphenylacetate but also has high concentrations of deleterious fermentation metabolites. Amino acid composition of the protein isolates is significantly correlated with abundances of many microbial taxa and metabolites, but the correlations are stronger in the low CHO medium. This study shows that low CHO conditions increase proteolytic fermentation and result in increased differences in microbiota response to protein isolates. It also showed that amino acid composition is highly associated with microbiota composition and function especially under low CHO conditions.

Carbohydrate Ingestion Increases Interstitial Glucose and Mitigates Neuromuscular Fatigue during Single-Leg Knee Extensions.

We aimed to investigate the neuromuscular contributions to enhanced fatigue resistance with carbohydrate (CHO) ingestion and to identify whether fatigue is associated with changes in interstitial glucose levels assessed using a continuous glucose monitor (CGM). Twelve healthy participants (six males, six females) performed isokinetic single-leg knee extensions (90°·s -1 ) at 20% of the maximal voluntary contraction (MVC) torque until MVC torque reached 60% of its initial value (i.e., task failure). Central and peripheral fatigue were evaluated every 15 min during the fatigue task using the interpolated twitch technique and electrically evoked torque. Using a single-blinded crossover design, participants ingested CHO (85 g sucrose per hour), or a placebo (PLA), at regular intervals during the fatigue task. Minute-by-minute interstitial glucose levels measured via CGM and whole blood glucose readings were obtained intermittently during the fatiguing task. CHO ingestion increased time to task failure over PLA (113 ± 69 vs 81 ± 49 min, mean ± SD; P < 0.001) and was associated with higher glycemia as measured by CGM (106 ± 18 vs 88 ± 10 mg·dL -1 , P < 0.001) and whole blood glucose sampling (104 ± 17 vs 89 ± 10 mg·dL -1 , P < 0.001). When assessing the values in the CHO condition at a similar time point to those at task failure in the PLA condition (i.e., ~81 min), MVC torque, percentage voluntary activation, and 10 Hz torque were all better preserved in the CHO versus PLA condition ( P < 0.05). Exogenous CHO intake mitigates neuromuscular fatigue at both the central and peripheral levels by raising glucose concentrations rather than by preventing hypoglycemia.

Carbohydrate intake before and during high intensity exercise with reduced muscle glycogen availability affects the speed of muscle reoxygenation and performance.

Muscle glycogen state and carbohydrate (CHO) supplementation before and during exercise may impact responses to high-intensity interval training (HIIT). This study determined cardiorespiratory, substrate metabolism, muscle oxygenation, and performance when completing HIIT with or without CHO supplementation in a muscle glycogen depleted state. On two occasions, in a cross-over design, eight male cyclists performed a glycogen depletion protocol prior to HIIT during which either a 6% CHO drink (60g.hr-1) or placebo (%CHO, PLA) was consumed. HIIT consisted of 5 × 2min at 80% peak power output (PPO), 3 × 10-min bouts of steady-state (SS) cycling (50, 55, 60% PPO), and a time-to-exhaustion (TTE) test. There was no difference in SS [Formula: see text], HR, substrate oxidation and gross efficiency (GE %) between CHO and PLA conditions. A faster rate of muscle reoxygenation (%. s-1) existed in PLA after the 1st (Δ-0.23 ± 0.22, d = 0.58, P < 0.05) and 3rd HIIT intervals (Δ-0.34 ± 0.25, d = 1.02, P < 0.05). TTE was greater in CHO (7.1 ± 5.4min) than PLA (2.5 ± 2.3min, d = 0.98, P < 0.05). CHO consumption before and during exercise under reduced muscle glycogen conditions did not suppress fat oxidation, suggesting a strong regulatory role of muscle glycogen on substrate metabolism. However, CHO ingestion provided a performance benefit under intense exercise conditions commenced with reduced muscle glycogen. More research is needed to understand the significance of altered muscle oxygenation patterns during exercise.

The Acute Effects of Milk Consumption on Systemic Inflammation after Combined Resistance and Plyometric Exercise in Young Adult Females.

High-intensity/impact exercise elicits a transient increase in inflammatory biomarkers. Consuming nutrient-dense wholefoods, like milk, following exercise may modulate post-exercise inflammation and aid recovery. We examined the effect of post-exercise skim milk consumption (versus an isoenergetic, isovolumetric carbohydrate [CHO] drink) on acute exercise-induced inflammation in untrained females. Using a randomized crossover design, 13 healthy females (age = 20 ± 2.3 y; BMI = 21.0 ± 1.1 kg/m2) completed two bouts of combined resistance/plyometric exercise followed by either skim milk (MILK) or CHO at 5-min and 1 h post-exercise. Serum interleukin [IL]-1β, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α) concentrations were measured at pre-exercise, 15-min, 75-min, 24 h, and 48 h post-exercise. IL-6 increased 15-min post-exercise vs. all other timepoints (time effect, p = 0.017). Between 24 and 48 h, IL-10 decreased and increased in the MILK and CHO conditions, respectively (interaction, p = 0.018). There were no significant effects for IL-1β or TNF-α. Relative concentrations of IL-1β (p = 0.049) and IL-10 (p = 0.028) at 48 h post-exercise were lower in MILK vs. CHO. Milk post-exercise did not influence the absolute concentration of pro-inflammatory cytokines; however, there were divergent responses for the anti-inflammatory cytokine, IL-10, and milk reduced the relative inflammatory response at 48 h (vs. CHO) for IL-1β and IL-10. This demonstrates the potential for milk to modulate inflammation post-exercise in this sample.

A Comparison Of Protein And Carbohydrate-fed Sprint Interval Training On Skeletal Muscle And Performance Adaptations

Sprint interval training (SIT) has emerged as a potent metabolic stimulus inducing beneficial musculoskeletal adaptations. However, nutritional support to optimise the adaptive response to SIT remains poorly characterised. Carbohydrate (CHO) has previously been shown to blunt metabolic adaptations to training while there is increased interest in the role of protein in regulating training adaptations. PURPOSE: The aim of this study was to determine the effects of whey protein concentrate (WPC) compared with CHO feeding on the acute regulation of skeletal muscle mitochondrial gene expression, enzyme activity and performance following a 3 week SIT intervention. METHODS: This study was ethically approved and conducted in line with the Declaration of Helsinki. Healthy, recreationally active (VO2 max <50 ml.kg-1.min-1) males (n = 17) were randomised to complete SIT under CHO or WPC conditions. Participants attended the lab after an overnight fast (≥10 h) and ingested 0.33 g.kg-1 body mass (BM) of WPC, or 0.91 g.kg-1 BM maltodextrin (CHO) 45 min prior to SIT consisting of four 30 s sprints at a resistance of 7.5 % BM, interspersed with 4 min recovery. Muscle biopsies were obtained under local anaesthetic from m. vastus lateralis at rest and 3 h post-exercise. RNA extracted from skeletal muscle underwent multiplex PCR to determine mRNA expression relative to reference gene UBE2D2. Independent t-tests determined between-group differences in changes from baseline. RESULTS: Acute changes in PGC-1α, NMRK2, NNMNAT1/3 were not differentially regulated by condition (p > 0.05). Fold-change in PDK4, SIRT4, NAMPT and NNMT were differentially regulated by nutrient condition following an acute bout of SIT (WPC vs CHO: 6.6. vs 2.6; 0.62 vs 0.86; 1.73 vs 1.14; 6.0 vs 2.8, respectively, p < 0.05). Citrate synthase and β-3-Hydroxyacyl-CoA dehydrogenase (HAD) enzyme activity increased to a greater extent in response to SIT with WPC (Fold change WPC vs CHO: 1.3 vs 1.1; 1.23 vs 1.02, respectively, p < 0.05). Post-SIT Wingate performance changes were not different between conditions (% change WPC vs CHO: 6.3 vs 4.1%, p > 0.05). CONCLUSION: Pre-exercise nutrients result in divergent regulation of mitochondrial enzyme activity and some genes in response to SIT, however this is not associated with differential performance adaptations.

Acute Effects of Milk vs. Carbohydrate on Bone Turnover Biomarkers Following Loading Exercise in Young Adult Females.

Dairy products and impact exercise have previously been identified to be independently beneficial for bone mineral properties, however, it is unknown how the combination of these two osteogenic interventions may alter acute bone turnover. Using a randomized crossover design, we compared the acute effects of consuming milk vs. an isoenergetic carbohydrate control beverage on bone biomarkers following loading exercise. Thirteen healthy female participants (Age = 20.3 ± 2.3y; BMI = 21.0 ± 1.1 kg/m2) consumed either 550 mL of 0% skim white milk (MILK) or 52.7 g of maltodextrin in 550 mL of water (CHO), both 5 min and 1 h following completion of a combined plyometric (198 impacts) and resistance exercise (3–4 sets/exercise, 8–12 reps/set, ∼75% 1-RM) bout. Venous blood samples were obtained pre-exercise, and 15 min, 75 min, 24 h and 48 h post-exercise to assess serum concentrations of bone resorption biomarkers, specifically carboxyl-terminal crosslinking telopeptide of type I collagen (CTX), receptor activator nuclear factor kappa-β ligand (RANKL), and sclerostin (SOST), as well as bone formation biomarkers, specifically osteoprotegerin (OPG) and osteocalcin (OC). When absolute biomarker concentrations were examined, there were no interaction or group effects for any biomarker, however, there were main time effects (p < 0.05) for RANKL, SOST, and OC, which were lower, and the OPG: OPG/RANKL ratio, which was higher at 75 min post-exercise compared with baseline in both conditions. In addition to assessing absolute biomarker concentrations at specific timepoints, we also evaluated the relative (% change) cumulative post-exercise response (75 min to 48 h) using an area under the curve (AUC) analysis. This analysis showed that the relative post-exercise CTX response was significantly lower in the MILK compared to the CHO condition (p = 0.03), with no differences observed in the other biomarkers. These results show that while milk does not appear to alter absolute concentrations of bone biomarkers compared to CHO, it may attenuate relative post-exercise bone resorption (i.e., blunt the usual catabolic response to exercise).

Carbohydrate Mouth Rinsing Does Not Alter Central or Peripheral Fatigue After High-Intensity and Low-Intensity Exercise in Men.

Black, CD, Haskins, KR, Bemben, MG, and Larson, RD. Carbohydrate mouth rinsing does not alter central or peripheral fatigue after high-intensity and low-intensity exercise in men. J Strength Cond Res 36(1): 142-148, 2022-Carbohydrate (CHO) mouth rinsing improves performance during endurance exercise. However, its ability to attenuate fatigue during strength-based exercise is less certain. This study sought to determine the effects of a CHO mouth rinse on torque production and voluntary activation (VA%) after high-intensity and low-intensity isometric exercise. Twelve male subjects (22.5 ± 2.3 years; 183.5 ± 6.5 cm; 82.2 ± 13.9 kg) completed 4 testing sessions in a double-blind crossover fashion. Knee extension maximal voluntary isometric strength (MVC) was assessed before(Pre), immediately (iPost-Ex), and 5 minutes (5-min Post Ex) after isometric exercise performed at 80% or 20% of MVC. An 8% CHO solution or placebo (PLA) was rinsed for 20 seconds after exercise. VA% was determined by twitch interpolation. A 2 condition (CHO vs. PLA) × 2 contraction intensity (20 vs. 80%) × 3 time (Pre, iPost Ex, and 5-min Post Ex) completely within subject-repeated measured analysis of variance was performed; statistical significance was set at p ≤ 0.05. Greater reductions in MVC were found at iPost-Ex after exercise at 20% compared with 80% of MVC (-25 ± 14% vs. -11 ± 8%; p < 0.001) as well as for VA% (-17 ± 14% vs. -8 ± 14%; p < 0.004). No differences were observed in the CHO vs. PLA condition (p ≥ 0.34). We were successful in eliciting differing levels of central and peripheral fatigue by exercising at a low and high intensity. Despite significantly larger declines in VA% after exercise at 20% of MVC, CHO mouth rinsing had no effects compared with placebo on any measured variable.

Circulating Levels of Bone Markers after Short-Term Intense Training with Increased Dairy Consumption in Adolescent Female Athletes.

Thirteen female adolescent soccer players (14.3 ± 1.3 years) participated in a cross-over, double-blind trial examining the effects of Greek yogurt (GY) consumption on bone biomarkers during 5 days of intense soccer training. The study took place over two intervention weeks, which consisted of a pre-training assessment day, 5 training days, and a post-training assessment day. Participants completed the GY condition and a carbohydrate isocaloric placebo control pudding condition (CHO) in random order, 4 weeks apart. Morning, fasted, resting blood samples were collected pre- and post-training in each condition. Total osteocalcin (tOC), undercarboxylated osteocalcin (unOC), C-terminal telopeptide of type 1 collagen (CTX), osteoprotegerin (OPG), and receptor activator nuclear factor kappa-β ligand (RANKL) were measured in serum. The results showed no effects for time (pre- to post-training) or condition, and no interaction for tOC, CTX, OPG, RANKL, and the OPG/RANKL ratio. A time-by-condition interaction (p = 0.011) was observed in unOC, reflecting a post-training decrease in the GY, but not the CHO condition (−26% vs. −3%, respectively). However, relative unOC (% of tOC) decreased post-training (−16%), with no differences between conditions. These findings suggest that short-term high-impact intense training had no direct catabolic impact on bone metabolism, with GY adding no benefit beyond that of the isocaloric CHO control pudding.

Caffeine coingested with carbohydrate on performance recovery in national-level paddlers: a randomized, double-blind, crossover, placebo-controlled trial.

Caffeine enhances muscle glycogen resynthesis postexercise; however, the next-day effects on recovery are unknown. The present study aimed to examine the effects of carbohydrate (CHO) supplementation with or without caffeine (CAF) 24-h following exhaustive exercise on time trial performance in elite paddling athletes. Nine highly trained male paddlers (21±2 y) completed three experimental trials in a randomized, double-blind, crossover manner. Following an exhaustive exercise session (20-km timed paddle) participants ingested: 1) 0.6 g/kg of carbohydrate (CHO); 2) 0.6 g/kg of carbohydrate with 6 mg/kg of caffeine (CAF+CHO); or 3) placebo (PLA), at four time-points (immediately after, and 2, 6, and 12-h postexercise) in addition to their typical dietary intake. After 24 h, 5 attempts of on-water 500-m paddling time-trial was performed, and the average time was recorded. Blood samples were taken at rest and following both the 20-km and the 5×500 m exercise to determine changes in plasma cortisol, insulin, and glucose. There was a significant main effect of condition (P<0.001), with post-hoc analysis revealing that both CHO conditions (CHO: 98.7±2.8 s, P=0.0003; CAF+CHO: 97.9±2.3 s, P=0.0002) were significantly faster compared to PLA (101.0±3.1 s); however, CAF did not augment time trial performance compared to CHO (P=0.16). There was no significant condition by time interactions for glucose, cortisol, or insulin before and after the 20-km depleting exercise and 500-m time trial. In elite male paddlers, CHO, independent of caffeine, enhanced time trial performance 24 hours following exhaustive exercise.

Glucose and Fructose Hydrogel Enhances Running Performance, Exogenous Carbohydrate Oxidation, and Gastrointestinal Tolerance.

Beneficial effects of carbohydrate (CHO) ingestion on exogenous CHO oxidation and endurance performance require a well-functioning gastrointestinal (GI) tract. However, GI complaints are common during endurance running. This study investigated the effect of a CHO solution-containing sodium alginate and pectin (hydrogel) on endurance running performance, exogenous and endogenous CHO oxidation, and GI symptoms. Eleven trained male runners, using a randomized, double-blind design, completed three 120-min steady-state runs at 68% V˙O2max, followed by a 5-km time-trial. Participants ingested 90 g·h-1 of 2:1 glucose-fructose (13C enriched) as a CHO hydrogel, a standard CHO solution (nonhydrogel), or a CHO-free placebo during the 120 min. Fat oxidation, total and exogenous CHO oxidation, plasma glucose oxidation, and endogenous glucose oxidation from liver and muscle glycogen were calculated using indirect calorimetry and isotope ratio mass spectrometry. GI symptoms were recorded throughout the trial. Time-trial performance was 7.6% and 5.6% faster after hydrogel ([min:s] 19:29 ± 2:24, P < 0.001) and nonhydrogel (19:54 ± 2:23, P = 0.002), respectively, versus placebo (21:05 ± 2:34). Time-trial performance after hydrogel was 2.1% faster (P = 0.033) than nonhydrogel. Absolute and relative exogenous CHO oxidation was greater with hydrogel (68.6 ± 10.8 g, 31.9% ± 2.7%; P = 0.01) versus nonhydrogel (63.4 ± 8.1 g, 29.3% ± 2.0%; P = 0.003). Absolute and relative endogenous CHO oxidation was lower in both CHO conditions compared with placebo (P < 0.001), with no difference between CHO conditions. Absolute and relative liver glucose oxidation and muscle glycogen oxidation were not different between CHO conditions. Total GI symptoms were not different between hydrogel and placebo, but GI symptoms were higher in nonhydrogel compared with placebo and hydrogel (P < 0.001). The ingestion of glucose and fructose in hydrogel form during running benefited endurance performance, exogenous CHO oxidation, and GI symptoms compared with a standard CHO solution.

Flattened cola improves high-intensity interval performance in competitive cyclists.

Some cyclists consume flattened cola during competitive events, but limited research has investigated if cola beverages elicit ergogenic effects, particularly on high-intensity exercise performance. Whether the potentially beneficial effects of cola are due to the caffeine and/or the carbohydrate content is also unclear. This study assessed the ergogenic effects of different cola beverages on performance during a constant power bout (CPB) and subsequent high-intensity interval efforts in competitive cyclists. In a randomized, double-blind, cross-over design, competitive cyclists (n = 13; [Formula: see text]O2max 65.7 ± 5.9mlkg-1min-1) completed a 45-min CPB at 69% of maximum workload (Wmax), followed by four maximal 1-min high-intensity intervals (HII) against a resistance of 0.5Nkg-1. Participants consumed 16mlkg-1 total (intermittantly at four time points) of flattened decaffinated diet cola (PLA), caffeinated diet cola (CAF) or cola containing caffeine and carbohydrates (CAF + CHO). During the CPB, ratings of perceived exertion were lower in the CAF + CHO and CAF conditions compared to PLA (both, P < 0.04). Compared to PLA, CAF + CHO and CAF similarly increased (all, P < 0.049) mean power (CAF + CHO: 448 ± 51W; CAF: 448 ± 50W; PLA: 434 ± 57W), minimum power (CAF + CHO: 353 ± 45W; CAF: 352 ± 51W; PLA: 324 ± 49W) and total work (CAF + CHO: 26.9 ± 3.1kJ; CAF: 26.9 ± 3.0kJ; PLA: 26.0 ± 3.4kJ), but not peak power (CAF + CHO: 692 ± 117W; CAF: 674 ± 114W; PLA: 670 ± 113W; all, P > 0.57) during the HII. Cola containing caffeine with or without carbohydrates favorably influenced perceived effort during the CPB and enhanced mean and minimum power during repeated maximal intervals. We provide evidence supporting the consumption of commercially available cola for high-intensity cycling in competitive cyclists.

Effects of two different doses of carbohydrate ingestion on taekwondo-related performance during a simulated tournament

BackgroundCarbohydrate (CHO) ingestion enhances exercise performance; however, the efficacy of CHO intake on repeated bouts of exercise simulating a taekwondo tournament is unknown. Therefore, the purpose was to compare the effects of two different doses of CHO on a sports-specific kicking test during a simulated taekwondo tournament compared to placebo (PLA).MethodsIn a double-blind, randomized-placebo controlled, cross-over trial, eleven junior male professional taekwondo athletes (age: 16 ± 0.8 years, body mass: 55.3 ± 7.3 kg) ingested one of three solutions: (i) high dose (C45): 45 g of CHO (60 g∙h− 1), (ii) low dose (C22.5): 22.5 g of CHO (30 g∙h− 1; both solutions containing 2:1 glucose:fructose), or a PLA immediately following each kicking test. The kicking test was repeated 5 times, separated by 45 mins of rest, simulating a typical taekwondo competition day. Ratings of perceived exertion (RPE) and gastrointestinal discomfort (GI) scores were collected immediately after, and blood glucose before each test.ResultsThe results revealed that C45 and C22.5 did not improve total, successful, or percentage of successful kicks compared to PLA (p > 0.05). Blood glucose was significantly higher following both CHO conditions compared with PLA across all five tests (p < 0.05). There were no differences between treatments or across tests for RPE (p > 0.05).ConclusionCHO intake, independent of the dose, did not alter taekwondo kick performance during a simulated taekwondo tournament.

Comparable Exogenous Carbohydrate Oxidation from Lactose or Sucrose during Exercise.

ABSTRACTPurposeIngesting readily oxidized carbohydrates (CHO) such as sucrose during exercise can improve endurance performance. Whether lactose can be utilized as a fuel source during exercise is unknown. The purpose of this study was to investigate the metabolic response to lactose ingestion during exercise, compared with sucrose or water.MethodsEleven participants (age, 22 ± 4 yr; V̇O2peak, 50.9 ± 4.7 mL·min−1·kg−1) cycled at 50% Wmax for 150 min on five occasions. Participants ingested CHO beverages (lactose or sucrose; 48 g·h−1, 0.8 g·min−1) or water throughout exercise. Total substrate and exogenous CHO oxidation was estimated using indirect calorimetry and stable isotope techniques (naturally high 13C-abundance CHO ingestion). Naturally low 13C-abundance CHO trials were conducted to correct background shifts in breath 13CO2 production. Venous blood samples were taken to determine plasma glucose, lactate, and nonesterified fatty acid concentrations.ResultsMean exogenous CHO oxidation rates were comparable with lactose (0.56 ± 0.19 g·min−1) and sucrose (0.61 ± 0.10 g·min−1; P = 0.49) ingestion. Endogenous CHO oxidation contributed less to energy expenditure in lactose (38% ± 14%) versus water (50% ± 11%, P = 0.01) and sucrose (50% ± 7%, P ≤ 0.05). Fat oxidation was higher in lactose (42% ± 8%) than in sucrose (28% ± 6%; P ≤ 0.01); CHO conditions were lower than water (50% ± 11%; P ≤ 0.05). Plasma glucose was higher in lactose and sucrose than in water (P ≤ 0.01); plasma lactate was higher in sucrose than in water (P ≤ 0.01); plasma nonesterified fatty acids were higher in water than in sucrose (P ≤ 0.01).ConclusionsLactose and sucrose exhibited similar exogenous CHO oxidation rates during exercise at moderate ingestion rates. Compared with sucrose ingestion, lactose resulted in higher fat and lower endogenous CHO oxidation.

A Carbohydrate Beverage Reduces Monocytes Expressing TLR4 in Children with Overweight or Obesity

Background:Childhood obesity is increasing, with about one-third of children overweight or obese. Obesity is characterized by a state of chronic low-grade inflammation that is related to cardiometabolic comorbidities. Inflammatory monocytes, which are classified into 3 different groups—classical, intermediate, and nonclassical monocytes, with Toll-like receptor 4 (TLR4+) expression indicating a proinflammatory state—underlie several obesity-associated morbidities. Objectives:This study aimed to assess the responses of monocyte populations to beverages of differing macronutrient composition in children with healthy weight (HW) or overweight/obesity (OW/OB). Methods:Ten HW children (5th to 84.9th percentile; mean age 12.29±2.5 y) and 7 children with OW/OB (85th to 99.99th percentile; mean age 11.96±3.8 y) completed the study. Adiposity was determined via DXA. Using a double-blinded, randomized, crossover design, participants consumed either a high-carbohydrate (CHO; 210 kcal; 0g fat/56g carbohydrates/0g protein) or a whole-eggbased high-protein/fat (EGG; 210 kcal; 15g fat/0g carbohydrates/18g protein) beverage. Venous blood was collected at baseline and 2 h postprandially for evaluation of metabolic and inflammatory responses. Repeated measures ANOVA and Pearson correlations were conducted. Results:Consuming the CHO beverage significantly reduced the primary outcome: TLR4+expression on classical monocytes in children with OW/OB only (25.60% decrease from baseline in OW/OB compared with 1.61% increase in HW). Children with OW/OB had significantly less percentages of TLR4+nonclassical monocytes than HW (47.66% lower after CHO). Insulin and glucose (secondary outcomes), were significantly higher after the CHO condition compared with baseline (230.61% and 9.93% increase, respectively). Changes in glucose were significantly and negatively related to changes in monocyte populations in the CHO condition. Conclusions:These data suggest that high-carbohydrate beverages alter monocyte populations in the blood in children with OW/OB, which is related to glucose metabolism. These findings have implications for nutritional recommendations in children with overweight/obesity. National Clinical Trial registry trial number: NCT03597542.

Potato ingestion is as effective as carbohydrate gels to support prolonged cycling performance.

Carbohydrate (CHO) ingestion is an established strategy to improve endurance performance. Race fuels should not only sustain performance but also be readily digested and absorbed. Potatoes are a whole-food-based option that fulfills these criteria, yet their impact on performance remains unexamined. We investigated the effects of potato purée ingestion during prolonged cycling on subsequent performance vs. commercial CHO gel or a water-only condition. Twelve cyclists (70.7 ± 7.7 kg, 173 ± 8 cm, 31 ± 9 yr, 22 ± 5.1% body fat; means ± SD) with average peak oxygen consumption (V̇o2peak) of 60.7 ± 9.0 mL·kg−1·min−1 performed a 2-h cycling challenge (60–85% V̇o2peak) followed by a time trial (TT; 6 kJ/kg body mass) while consuming potato, gel, or water in a randomized-crossover design. The race fuels were administered with [U-13C6]glucose for an indirect estimate of gastric emptying rate. Blood samples were collected throughout the trials. Blood glucose concentrations were higher (P < 0.001) in potato and gel conditions compared with water condition. Blood lactate concentrations were higher (P = 0.001) after the TT completion in both CHO conditions compared with water condition. TT performance was improved (P = 0.032) in both potato (33.0 ± 4.5 min) and gel (33.0 ± 4.2 min) conditions compared with water condition (39.5 ± 7.9 min). Moreover, no difference was observed in TT performance between CHO conditions (P = 1.00). In conclusion, potato and gel ingestion equally sustained blood glucose concentrations and TT performance. Our results support the effective use of potatoes to support race performance for trained cyclists.NEW & NOTEWORTHY The ingestion of concentrated carbohydrate gels during prolonged exercise has been shown to promote carbohydrate availability and improve exercise performance. Our study aim was to expand and diversify race fueling menus for athletes by providing an evidence-based whole-food alternative to the routine ingestion of gels during training and competition. Our work shows that russet potato ingestion during prolonged cycling is as effective as carbohydrate gels to support exercise performance in trained athletes.

Effects of carbohydrate and glutamine supplementation on cytokine production by monocytes after exercise in hypoxia: A crossover, randomized, double-blind pilot study.

The aim of this study was to evaluate the combined effects of carbohydrate (CHO) and glutamine (Gln) supplementation on cytokine production by monocytes after exercise until exhaustion performed in hypoxia. Fifteen physically active men underwent three exercises until exhaustion with an intensity of 70% maximal oxygen intake at a simulated height of 4500 m under the following supplementation: placebo, CHO (maltodextrin 8%/200 mL for 20 min), and CHO + Gln (Gln 20 g/d for 6 d and maltodextrin 8%/200 mL for 20 min) during exercise and for 2 h of recovery. Analysis of variance for repeated measures followed by the Tukey's post hoc test was realized and P < 0.05 was considered statistically significant. Oxygen saturation of arterial blood (SaO2%) decreased in the three trials compared with baseline. Two hours post-exercise, the SaO2% was high in CHO + Gln condition compared with placebo. Two hours after exercise, interleukin (IL)-1β decreased compared with post-exercise in placebo and was lower compared with baseline in the CHO + Gln condition. Tumor necrosis factor-α decreased 2 h after exercise compared with baseline and pre-exercise in the CHO + Gln condition. No changes were observed in myeloperoxidase or IL-6 production. Two hours after exercise, Gln decreased compared with baseline and post-exercise in placebo and decreased 2 h after exercise in relation to post-exercise in the CHO condition. Gln increased post-exercise compared with pre-exercise in the CHO + Gln condition. Although erythropoietin did not change in this condition, it was high post-exercise and 2 h after exercise in the placebo condition compared with baseline and 2 h after exercise compared with baseline and pre-exercise in the CHO condition. Gln supplementation for 6 d before exercise, associated with CHO supplementation during exercise, was able to revert Gln reduction after exercise and after 2 h of recovery and may have contributed to reducing tumor necrosis factor-α production, suggesting a possible anti-inflammatory effect of supplementation.

Impact of a Carbohydrate Mouth Rinse on Quadriceps Muscle Function and Corticomotor Excitability.

The purpose of this investigation is to determine the effects of different forms of a CHO MR on quadriceps muscle performance and corticospinal motor excitability. Ten subjects (5 females, 5 males; 25±1 years; 1.71±0.03 m 73±5 kg) completed 4 trials. A different MR condition was applied during each trial (Placebo (PLA), 6.4% glucose (GLU), 6.4% maltose (MAL), 6.4% maltodextrin (MDX)). Maximal voluntary contraction (MVIC) of the right quadriceps and motor-evoked potential (MEP) of the right rectus femoris was determined pre (10 min), immediately after, and post (10 min) MR. MEP was precipitated by transcranial magnetic stimulation (TMS) during muscle contraction (50% of MVIC). MR was held in the mouth for 20 s and treatments were applied using a Latin square design. The relative change in MEP from pre-measures was different across treatments (p=0.025) but was not different across time (p=0.357). Relative change in MEP was greater for all CHO conditions immediately after (GLU=2.58±5.33%; MAL=3.92±3.90%; MDX=18.28±5.57%) and 10 min after (GLU=14.09±13.96%; MAL=8.64±8.67%; MDX=31.54±12.77%) MR compared to PLA (Immediately after=-2.19±4.25%, 10 min=-13.41±7.46%). The relative change in MVC was greater for CHO conditions immediately (GLU=3.98±2.49%; MAL=5.89±2.29.90%; MDX=7.66±1.93%) and 10 min after (GLU=7.22±2.77%; MAL=10.26±4.22%; MDX=10.18±1.50%) MR compared to PLA (Immediately after=-3.24±1.50%, 10 min=-6.46±2.22%). CHO MR increased corticospinal motor excitability and quadriceps muscle performance immediately and 10 min after application; however, the form of CHO used did not influence this response.

Dietary Effects of Replacing Carbohydrate-based Breakfast Foods with Eggs in Adults at Risk for Type 2 Diabetes (P08-044-19)

ObjectivesTo assess the effect of breakfast egg intake, vs. energy-matched carbohydrate (CHO)-based foods, on daily energy and select nutrient intakes in free-living adults at-risk for type 2 diabetes. MethodsOverweight or obese adults with prediabetes and/or metabolic syndrome were included in this randomized crossover study consisting of two 4-wk dietary intervention periods, separated by a ≥4 wk washout. During each intervention, subjects consumed study products containing either 2 eggs/d, 6 d/wk (12 eggs/wk) at breakfast, or energy-matched CHO-based foods. Means for energy and macronutrient contents of the study breakfast meals for both interventions were approximately 550 kcal, 31–32% energy from fat and 10.5% energy from saturated fat; protein energy was 25.9% and 12.1% for the egg and CHO meals, respectively. Subjects were instructed to incorporate the study breakfast meals into their habitual diets and maintain other lifestyle habits. Daily energy, macronutrients, fiber, cholesterol, sodium and calcium intakes were assessed by 3-d diet records at baseline and at the end of each condition. Dietary data was analyzed using the Food Processor software (v11.4). ResultsOverall, 30 subjects (11 male; 19 female) with mean age of 53.5 ± 1.9 y and body mass index (BMI) of 31.9 ± 0.7 kg/m2 provided evaluable data. Reported median daily energy intake during the egg condition was 2145 kcal, which was significantly (P = 0.008) higher than the 1996 kcal reported during the CHO condition (see Table). Dietary analyses indicate the 149 kcal/d difference was due to intake of foods other than the study products. Despite the higher reported energy intake during the egg condition, weight change from baseline did not differ between the interventions (–0.1 and 0.2 kg, for egg and CHO conditions, respectively). Median % energy intake from CHO was significantly lower and daily sodium and cholesterol intakes significantly higher during the egg condition. ConclusionsIntake of 12 eggs/wk at breakfast, vs. energy-matched CHO foods, resulted in greater reported daily energy intake and no change in body weight. Further investigation is needed to assess the impact of egg-based breakfast meals on appetite and energy expenditure. Funding SourcesAmerican Egg Board/Egg Nutrition Center, Park Ridge, IL. Supporting Tables, Images and/or Graphs▪

The Effect of Replacing Carbohydrate-based Breakfast Foods with Eggs on Cardiometabolic Risk Factors in Adults at Risk for Type 2 Diabetes (P08-045-19)

ObjectivesTo assess the effect of breakfast egg intake, vs. energy-matched carbohydrate (CHO)-based foods, on insulin sensitivity and markers of cardiometabolic health in adults at-risk for type 2 diabetes. MethodsOverweight or obese adults with prediabetes and/or metabolic syndrome were included in this randomized crossover study consisting of two 4-wk dietary intervention periods, separated by a ≥4 wk washout. During each intervention, subjects consumed study products containing either 2 eggs/d for 6 d/wk (12 eggs/wk) or energy-matched CHO-based foods for breakfast. Percent changes from baseline were assessed for insulin sensitivity; CHO metabolism; lipid metabolism, including lipoprotein lipids, subfactions and particle sizes; high-sensitivity C-reactive protein (hs-CRP); and blood pressures (BP). ResultsOverall, 30 subjects (11 male; 19 female) with mean age of 53.5 ± 1.9 y and body mass index (BMI) of 31.9 ± 0.7 kg/m2 provided evaluable data. Median low-density lipoprotein cholesterol (LDL-C) decreased by 6.0% from a baseline of 119 mg/dL after 4-wk intake of the CHO breakfast foods, which was larger than the 2.9% reduction during the egg condition (P = 0.023 between diets). Mean systolic blood pressure was reduced significantly more during the egg condition vs. the CHO condition (2.7% vs. 0.0%, respectively, P = 0.018) from a baseline value of 127 mmHg. None of the other cardiometabolic risk factor parameters showed significant differences in response between diet conditions. ConclusionsIntake of 12 eggs/wk for breakfast, vs. energy matched CHO-based foods, did not adversely affect the cardiometabolic risk factor profile in men and women at risk for diabetes. Funding SourcesAmerican Egg Board/Egg Nutrition Center, Park Ridge, IL Supporting Tables, Images and/or Graphs▪