The Ingestion of 39 or 64 g·hr−1 of Carbohydrate is Equally Effective at Improving Endurance Exercise Performance in Cyclists

Newell, Michael L.; Hunter, Angus M.; Lawrence, Claire; Tipton, Kevin D.; Galloway, Stuart D. R.

doi:10.1123/ijsnem.2014-0134

Cited by 13 publications

(21 citation statements)

References 22 publications

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“…However, one must cautiously explore this approach as to avoid overwhelming the gastrointestinal system potentially leading to cramping and discomfort once exercise begins. In this respect one should consider the findings of Newell et al [ 55 ] who had 20 well-trained, experienced cyclists perform four different feeding conditions (no carbohydrate [0 g/h] control, 20 g/h, 39 g/h or 64 g/h) throughout completion of a two-hour cycling bout at 95% lactate threshold (185 ± 25 watts) followed by completion of a standardized time trial. When carbohydrates were ingested at a dosage of 39 or 64 g/h, time trial performance was significantly improved compared to the control group.…”

Section: Introductionmentioning

confidence: 99%

International society of sports nutrition position stand: nutrient timing

Kerksick

Arent

Schöenfeld

et al. 2017

Journal of the International Society of Sports Nutrition

418

293

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Position statementThe International Society of Sports Nutrition (ISSN) provides an objective and critical review regarding the timing of macronutrients in reference to healthy, exercising adults and in particular highly trained individuals on exercise performance and body composition. The following points summarize the position of the ISSN:Nutrient timing incorporates the use of methodical planning and eating of whole foods, fortified foods and dietary supplements. The timing of energy intake and the ratio of certain ingested macronutrients may enhance recovery and tissue repair, augment muscle protein synthesis (MPS), and improve mood states following high-volume or intense exercise.Endogenous glycogen stores are maximized by following a high-carbohydrate diet (8–12 g of carbohydrate/kg/day [g/kg/day]); moreover, these stores are depleted most by high volume exercise.If rapid restoration of glycogen is required (< 4 h of recovery time) then the following strategies should be considered:aggressive carbohydrate refeeding (1.2 g/kg/h) with a preference towards carbohydrate sources that have a high (> 70) glycemic indexthe addition of caffeine (3–8 mg/kg)combining carbohydrates (0.8 g/kg/h) with protein (0.2–0.4 g/kg/h) Extended (> 60 min) bouts of high intensity (> 70% VO2max) exercise challenge fuel supply and fluid regulation, thus carbohydrate should be consumed at a rate of ~30–60 g of carbohydrate/h in a 6–8% carbohydrate-electrolyte solution (6–12 fluid ounces) every 10–15 min throughout the entire exercise bout, particularly in those exercise bouts that span beyond 70 min. When carbohydrate delivery is inadequate, adding protein may help increase performance, ameliorate muscle damage, promote euglycemia and facilitate glycogen re-synthesis.Carbohydrate ingestion throughout resistance exercise (e.g., 3–6 sets of 8–12 repetition maximum [RM] using multiple exercises targeting all major muscle groups) has been shown to promote euglycemia and higher glycogen stores. Consuming carbohydrate solely or in combination with protein during resistance exercise increases muscle glycogen stores, ameliorates muscle damage, and facilitates greater acute and chronic training adaptations.Meeting the total daily intake of protein, preferably with evenly spaced protein feedings (approximately every 3 h during the day), should be viewed as a primary area of emphasis for exercising individuals.Ingestion of essential amino acids (EAA; approximately 10 g)either in free form or as part of a protein bolus of approximately 20–40 g has been shown to maximally stimulate muscle protein synthesis (MPS).Pre- and/or post-exercise nutritional interventions (carbohydrate + protein or protein alone) may operate as an effective strategy to support increases in strength and improvements in body composition. However, the size and timing of a pre-exercise meal may impact the extent to which post-exercise protein feeding is required.Post-exercise ingestion (immediately to 2-h post) of high-quality protein sources stimulates robust increases in MPS....

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Section: Introductionmentioning

confidence: 99%

International society of sports nutrition position stand: nutrient timing

Kerksick

Arent

Schöenfeld

et al. 2017

Journal of the International Society of Sports Nutrition

418

293

View full text Add to dashboard Cite

show abstract

“…Tests with commercial sports drinks prove (Newell et al, 2015;Roberts et al, 2012) or disprove (Burke et al, 2005;Coletta et al, 2013;Qin et al, 2017;van Nieuwenhoven et al, 2005) the ergogenic effects. Coombes and Hamilton (2000) concluded in their tests that no isotonic sports drinks currently on the market are superior to any other.…”

Section: Introductionmentioning

confidence: 99%

Effects of Commercial Isotonic Sports Drinks during Intermittent Exertion

Zart

Fröhlich

2019

IJKSS

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Background: Carbohydrate-electrolyte drinks support performance and recovery during athletic activities. The impact of these isotonic drinks is usually verified by means of placebos without energy. Objective: We checked the extent to which commercial sports drinks may be superior to a syrup–water mixture, similar in calorific value, during an intermittent exertion. Method: In a cross-sectional study, three homogeneously parallelized groups, including a total of 35 test subjects, performed full-strain endurance and speed tests (5,000 m, 3,000 m, 1,500 m, 800 m, 400 m, and 200 m). During the rest intervals, isocaloric drinks with the same CHO (6,66–7,0 g), but different sugar (ISO1: 2,46 g; ISO2: 5,6 g; syrup: 6,7 g) and electrolyte content were given in a randomized way. The parameters of running performance, body weight, rating of perceived exertion, heart rate, and blood lactate concentration were analyzed. Results: Over the distances (p≥0.10), the results did not show any ergogenic effect of the isotonic drinks in comparison with the syrup–water mixture. There were also no significant differences in terms of rates of perceived exertion (p≥0.26) and the physiological parameters of heart rate (p≥0.30) and blood lactate (p≥0.18) among the groups. Conclusion: During intermittent and repetitive exertion below 30 minutes, homemade energy drinks exhibited the same effects as commercial sports drinks.

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“…These authors reported a non-significant but ‘likely’ 2.3% improvement in performance when comparing 60 vs. 30 g·h −1 suggesting a dose-response effect of CHO feeding rate. We recently reported that a 2.3% performance gain would not necessarily be ‘likely’ due to typical variance observed in performance outcome measures [ 7 ] when using a more suitably powered design. In addition, there has yet to be an extensive exploration of the association between multiple metabolic variables and subsequent exercise performance outcomes using a dose-response investigation.…”

Section: Introductionmentioning

confidence: 99%

Metabolic Responses to Carbohydrate Ingestion during Exercise: Associations between Carbohydrate Dose and Endurance Performance

et al. 2018

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Carbohydrate (CHO) ingestion during exercise lasting less than three hours improves endurance exercise performance but there is still debate about the optimal dose. We utilised stable isotopes and blood metabolite profiles to further examine metabolic responses to CHO (glucose only) ingestion in the 20–64 g·h−1 range, and to determine the association with performance outcome. In a double-blind, randomized cross-over design, male cyclists (n = 20, mean ± SD, age 34 ± 10 years, mass 75.8 ± 9 kg, peak power output 394 ± 36 W, VO2max 62 ± 9 mL·kg−1·min−1) completed four main experimental trials. Each trial involved a two-hour constant load ride (185 ± 25 W) followed by a time trial, where one of three CHO beverages, or a control (water), were administered every 15 min, providing 0, 20, 39 or 64 g CHO·h−1. Dual glucose tracer techniques, indirect calorimetry and blood analyses were used to determine glucose kinetics, exogenous CHO oxidation (EXO), endogenous CHO and fat oxidation; and metabolite responses. Regression analysis revealed that total exogenous CHO oxidised in the second hour of exercise, and suppression of serum NEFA concentration provided the best prediction model of performance outcome. However, the model could only explain ~19% of the variance in performance outcome. The present data demonstrate that consuming ~40 g·h−1 of CHO appears to be the minimum ingestion rate required to induce metabolic effects that are sufficient to impact upon performance outcome. These data highlight a lack of performance benefit and few changes in metabolic outcomes beyond an ingestion rate of 39 g·h−1. Further work is required to explore dose-response effects of CHO feeding and associations between multiple metabolic parameters and subsequent performance outcome.

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The Ingestion of 39 or 64 g·hr−1 of Carbohydrate is Equally Effective at Improving Endurance Exercise Performance in Cyclists

Cited by 13 publications

References 22 publications

International society of sports nutrition position stand: nutrient timing

International society of sports nutrition position stand: nutrient timing

Effects of Commercial Isotonic Sports Drinks during Intermittent Exertion

Metabolic Responses to Carbohydrate Ingestion during Exercise: Associations between Carbohydrate Dose and Endurance Performance

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