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Cited by 170Sports Performance and TrainingMuscle metabolism and nutritionThermoregulation and physiological responses

Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers

Open access
Burke, Louise M., Jeukendrup, Asker E., Jones, Andrew M., Mooses, Martin·2019·International Journal of Sport Nutrition and Exercise Metabolism
DOI 10.1123/ijsnem.2019-0004
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Abstract

Distance events in Athletics include cross country, 10,000-m track race, half-marathon and marathon road races, and 20- and 50-km race walking events over different terrain and environmental conditions. Race times for elite performers span ∼26 min to >4 hr, with key factors for success being a high aerobic power, the ability to exercise at a large fraction of this power, and high running/walking economy. Nutrition-related contributors include body mass and anthropometry, capacity to use fuels, particularly carbohydrate (CHO) to produce adenosine triphosphate economically over the duration of the event, and maintenance of reasonable hydration status in the face of sweat losses induced by exercise intensity and the environment. Race nutrition strategies include CHO-rich eating in the hours per days prior to the event to store glycogen in amounts sufficient for event fuel needs, and in some cases, in-race consumption of CHO and fluid to offset event losses. Beneficial CHO intakes range from small amounts, including mouth rinsing, in the case of shorter events to high rates of intake (75–90 g/hr) in the longest races. A personalized and practiced race nutrition plan should balance the benefits of fluid and CHO consumed within practical opportunities, against the time, cost, and risk of gut discomfort. In hot environments, prerace hyperhydration or cooling strategies may provide a small but useful offset to the accrued thermal challenge and fluid deficit. Sports foods (drinks, gels, etc.) may assist in meeting training/race nutrition plans, with caffeine, and, perhaps nitrate being used as evidence-based performance supplements.

AI snapshot

Written from the paper’s full text.

TL;DR

This review summarizes contemporary nutrition strategies for distance runners and race walkers, emphasizing carbohydrate availability, hydration, supplements, and heat. It recommends personalized, practiced race plans with carbohydrate intakes ranging from mouth rinsing in shorter events to 75–90 g/hr in the longest races, plus caffeine and possibly nitrate.

Key findings

  • Carbohydrate ingestion during endurance exercise improved performance in 82% of studies (50 of 61 studies, 679 subjects); optimal intakes are ∼75–90 g/hr for longer events such as marathon and 50-km race walk, with smaller amounts or mouth rinsing for shorter events.
  • Prerace glycogen strategies differ by event: <90-min events can normalize glycogen with 7–10 g/kg body mass for 24 hr, while marathon and 50-km race walk benefit from CHO loading at 10–12 g/kg/day for 36–48 hr, often with a low-fiber diet.
  • A fluid deficit >2–3% body mass is typically associated with increased perception of effort and core temperature and reduced performance, especially in hot environments; in-race fluid plans require cost-benefit analysis because of aid-station logistics and gut discomfort risk.
  • Caffeine (∼3 mg/kg, up to 6 mg/kg) before and/or during distance events and nitrate (∼8 mmol 2–3 hr prerace) are the performance supplements most likely to benefit distance athletes, though nitrate seems less effective in elite athletes; a ketogenic low-CHO, high-fat diet increased muscle fat oxidation ∼2.5× but impaired exercise economy and negated performance benefits in elite race walkers.

Methods

  • Review article synthesizing contemporary nutrition knowledge for distance runners and race walkers, covering events from ∼26 min (10,000-m track) to >4 hr.
  • Uses narrative synthesis and tables on event characteristics, prerace and in-race nutrition, supplements, hyperhydration, and cooling; no primary data collection or formal systematic review search/quality appraisal is described.
  • Includes two commentaries: dietary practices of East African runners and modeling the 2-hr marathon.

Limitations

  • Stated: evidence for performance supplements is sparse and variable, often underpowered by small samples and performance protocols lacking sufficient reliability to detect small but meaningful benefits.
  • Stated: some periodization areas are controversial or confusing due to different definitions or inaccurate descriptions; hot-environment strategy literature is sparse and requires investigation.
  • Stated: dietary surveys of East African runners are limited to home environments and training camps, with artifacts in dietary survey methodology and energy availability calculations.
  • Evident: as a narrative review, evidence selection and recommendations are not based on a systematic search or formal risk-of-bias assessment, and some practical recommendations rely on expert opinion or personal observations.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1123/ijsnem.2019-0004

Cites

99 of 99 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 81 cited sources checked · 0 supported · 0 flagged

  • Findingcitation

    The authors of this paper have assisted several elite athletes to break Olympic and world records or marks using aggressive hydration and carbohydrate feeding plans targeting 90 g/hr.

    “Despite the practical challenges, the authors of this paper have assisted several elite athletes to break Olympic and world records/marks using aggressive hydration and CHO feeding plans (targeting 90 g/h); some of which have been described independently ( Caesar, 2017;Hutchinson, 2017).”
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    • cites Caesar, 2017

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    • cites Hutchinson, 2017

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  • Premisecitation

    Exercise above lactate threshold incurs a nonlinear increase in metabolic, respiratory, and perceptual stress and more rapid fatigue due to metabolic acidosis or accelerated muscle glycogen depletion.

    “Exercise above LT incurs a nonlinear increase in metabolic, respiratory, and perceptual stress and a more rapid fatigue development due to the effects of metabolic acidosis on contractile function or an accelerated depletion of muscle glycogen (Sahlin, 1992).”
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    • cites Sahlin, 1992 source

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  • Premisecitation

    Running economy is associated with anthropometric, physiological, metabolic, biomechanical, and technical factors.

    “Running economy is associated with anthropometric (including segmental mass distribution), physiological, metabolic, biomechanical, and technical factors (Saunders et al., 2004).”
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    • cites Saunders et al., 2004 source

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  • Premisecitation

    Subelite endurance athletes performed better after 3 weeks of training with strategic manipulations of carbohydrate availability.

    “although subelite endurance athletes performed better after undertaking 3 weeks of training with strategic manipulations of CHO availability (Marquet et al., 2016)”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Marquet et al., 2016 source

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  • Premisecitation

    The fraction of VO2max that can be sustained for a given exercise duration is rarely greater than 90% in distance events.

    “The fraction of VO 2 max that can be sustained for a given exercise duration, which is rarely >90% VO 2 max in distance events, is related to muscle oxidative capacity (Gollnick & Saltin, 1982;Ivy et al., 1980)”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Gollnick & Saltin, 1982 source

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    • cites Ivy et al., 1980 source

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  • Classified as probably not a substantial claim. 9
  • May combine two claims. 23

  • Classified as probably not a substantial claim.

    Findingnone given

    The literature on the specific benefits of these strategies in high-performance running or racewalking scenarios is sparse.

    “The literature on the specific benefits of these strategies (see Table 6) in high-performance running or racewalking scenarios is sparse; an investigation is required”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Findingreasoning

    If a running economy of 190 ml/kg/km at 21.1 km/hr and BM of 55 kg are assumed, the total energy cost of running 42.2 km is calculated at ~2,200 kcal (9,210 kJ).

    “if we assume a running economy of 190 ml•kg -1 •km -1 at 21.1 km/hr and BM of 55 kg, the total energy cost of running 42.2 km is calculated at ∼2,200 kcal (9,210 kJ).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Running economy of 190 ml/kg/km at 21.1 km/hr for the hypothetical marathon runner.
    • The authors state this as an assumption: Body mass of 55 kg for the hypothetical marathon runner.

  • May combine two claims.

    Premisecitation

    Distance events from about 26 min in the 10,000-m track race to more than 3.5 hr in the 50-km race walk are submaximal, with mean energy requirements of about 75-92% of maximal oxygen uptake.

    “The distance events (from ∼26 min in the 10,000-m track race to >3.5 hr in the 50-km race walk) are considered “submaximal,” with mean energy requirements of ∼75-92% of maximal oxygen uptake ( VO 2 max; Londeree, 1986).”
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    • cites Londeree, 1986

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    Interpretationnone given

    Substrate availability for muscle (glycogen and glucose) and brain (glucose) is a key issue for many distance events, along with offsetting sweat loss to preserve plasma volume and cardiac output.

    “Table 1 indicates that substrate availability for the muscle (glycogen and glucose) and brain (glucose) is a key issue for many distance events, along with the offset of sweat loss to preserve plasma volume and cardiac output.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Endurance training may improve exercise economy via improved muscle oxidative capacity, changes in motor unit recruitment, reductions in ventilation and heart rate at the same intensity, and improved technique.

    “Endurance training may improve exercise economy via improved muscle oxidative capacity and associated changes in motor unit recruitment patterns, reductions in exercise ventilation and heart rate for the same exercise intensity, and improved technique (Saunders et al., 2004;Williams & Cavanagh, 1997).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Saunders et al., 2004 source

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    • cites Williams & Cavanagh, 1997

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    Premisecitation

    A 10,000-m track event likely exceeds critical speed for at least some portions of the race, so performance depends on the interplay between critical speed and the curvature constant of the speed-time relationship.

    “while a 10,000-m track event likely exceeds CS, at least for some portions of the race, such that the performance depends on the interplay between CS and the curvature constant of the speed-time relationship (Jones & Vanhatalo, 2017).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Jones & Vanhatalo, 2017

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    Premisecitation

    Elite female distance athletes typically have VO2max values of 65-80 ml/kg/min, while elite male athletes have higher values of 70-85 ml/kg/min.

    “Elite female distance athletes typically possess values of 65-80 ml•kg -1 •min -1 , whereas elite male athletes possess higher values (70-85 ml•kg -1 •min -1 ; Joyner & Coyle, 2008), due to factors including higher hemoglobin concentrations, which increase O 2 delivery at the maximal cardiac output, and lower fat mass.”
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    • cites Joyner & Coyle, 2008 source

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  • Classified as probably not a substantial claim.

    Premisecitation

    It is not sustainable from a health and/or performance perspective to be at ideal race body composition year-round.

    “A recent science-based case study of an Olympic female middle-distance runner argued that it is not sustainable from a health and/or performance perspective to be at ideal race body composition year-round (Stellingwerff, 2018).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Stellingwerff, 2018 source

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    Interpretationcitation

    A periodized approach to body composition supported targeted peak performances and minimized injury risk while maximizing training adaptation and long-term athlete health through management of energy availability.

    “This approach supported targeted peak performances and minimized risk of injury while maximizing training adaptation and long-term athlete health through management of energy availability.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Stellingwerff, 2018 source

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  • May combine two claims.

    Premisecitation

    In the marathon and 50-km race walk, glycogen can become limiting for race performance, and protocols that supercompensate glycogen are beneficial.

    “In the marathon and 50-km race walk where glycogen can become limiting for race performance, the protocols that supercompensate glycogen are beneficial.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Karlsson & Saltin, 1971 source

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    • cites Hyman, 1970

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Problems associated with chronic or severe low energy availability, known as relative energy deficiency in sports, are well known.

    “Problems associated with chronic or severe low energy availability, known as relative energy deficiency in sports, are well known (Mountjoy et al., 2018); specific issues in relation to Athletics are covered by Melin et al. (2019).”
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    • cites Mountjoy et al., 2018 source

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    • cites Melin et al., 2019 source

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    Premisecitation

    Both periodized carbohydrate availability and constant high carbohydrate availability were associated with better race outcomes than chronic 3.5-week exposure to a ketogenic low-carbohydrate high-fat diet, despite substantial increases in muscle fat oxidation.

    “Meanwhile, both dietary approaches were associated with better race outcomes than chronic (3.5 week) exposure to a ketogenic low CHO, high-fat diet, despite its achievement of substantial (∼2.5 ×) increases in muscle fat oxidation (Burke et al., 2017).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Burke et al., 2017 source

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  • Classified as probably not a substantial claim.

    Interpretationreasoning

    The specific needs of long-distance races raise potential new uses of sports foods and performance supplements, based on physiological, biochemical, and central nervous system factors that limit performance in these races and on the opportunity to consume products within the event for races of half marathon and longer.

    “The specific needs of long-distance races raise potential new uses of sports foods and performance supplements, based on the specific physiological, biochemical, and central nervous system factors that limit performance in these races, as well as the opportunity to consume products within the event, at least for races of half marathon and longer.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationnone given

    A low-residue (fiber) diet may reduce the risk of gut issues during the race and achieve a small reduction in body mass to partially offset the mass of additional muscle glycogen and stored water.

    “This is often undertaken in conjunction with a low residue (fiber) diet (Table 3), which may not only reduce the risk of gut issues during the race but also achieve a small reduction in BM to partially offset the mass of the additional muscle glycogen and stored water.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Additional benefits of a prerace reduction in intestinal fiber content for distance runners and walkers include a lowered risk of gut discomfort or upset during the race and simplification of the logistics of bowel evacuations in the hours prior to a race.
    • Rests on an assumption: Disadvantages of the prerace low-fiber diet include a lack of food variety, a short-term reduction in dietary quality or micronutrient density, and discomfort due to lower satiety or hunger.
    • Rests on an assumption: The low-fiber diet can be integrated with a carbohydrate-loading protocol and may assist with achieving targets for large amounts of carbohydrate intake due to the increased energy density of food choices.

  • May combine two claims.

    Premisecitation

    More contemporary recommendations suggest smaller amounts of carbohydrate for shorter duration events and higher rates of intake for longer events lasting more than 2.5 hr.

    “More contemporary recommendations (Burke et al., 2011;Thomas et al., 2016), however, suggest smaller amounts for shorter duration events and higher rates of intake for longer events (>2.5 hr), based on the mechanism of likely benefits to performance as well as the recognition that higher amounts can be tolerated and utilized than previously considered.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Burke et al., 2011 source

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    • cites Thomas et al., 2016

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  • May combine two claims.

    Premisecitation

    Combining glucose-based carbohydrate sources with fructose increases total exogenous carbohydrate oxidation during exercise, with rates as high as 1.75 g/min.

    “Combining glucose-based CHO sources with fructose (transported in the intestine by GLUT5) increases total exogenous CHO oxidation during exercise, with rates as high as 1.75 g/min (Jeukendrup & Chambers, 2010).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Jeukendrup & Chambers, 2010

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  • May combine two claims.

    Premisecitation

    Narrative review, meta-analysis, and dose-response approaches found that higher amounts of carbohydrate promote better performance in longer events relevant to the marathon and 50-km race walk, with optimal intakes of about 75-90 g/hr.

    “Narrative review (Stellingwerff & Cox, 2014), meta-analysis (Vandenbogaerde & Hopkins, 2011), and dose-response (Smith et al., 2010) approaches to this topic have found that higher amounts of CHO promote better performance in longer events relevant to the marathon and 50-km race walk, with optimal intakes of ∼75-90 g/hr.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Stellingwerff & Cox, 2014 source

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    • cites Vandenbogaerde & Hopkins, 2011

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    • cites Smith et al., 2010

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  • May combine two claims.

    Premisecitation

    A preevent carbohydrate-focused meal and a small carbohydrate-rich snack during the race warm-up contribute to fuel availability.

    “Further contributions to fuel availability are provided by a preevent CHO-focused meal and a small CHO-rich snack (e.g., sports gel or drink) during the race warm-up.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Burke et al., 2011 source

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  • May combine two claims.

    Premisecitation

    Chronic exposure to higher carbohydrate intakes by athletes, including exercise intake, increases gut tolerance, intestinal absorption, and muscle oxidation of carbohydrate consumed during exercise.

    “However, as reviewed by Jeukendrup (2017b), sodium-dependent glucose transporter abundance and activity in animals is increased by a CHO-rich diet; furthermore, chronic exposure to higher CHO intakes by athletes, including exercise intake, increases gut tolerance, intestinal absorption, and muscle oxidation of CHO consumed during exercise (Costa et al., 2017;Cox et al., 2010).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Costa et al., 2017 source

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    • cites Cox et al., 2010 source

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  • May combine two claims.

    Premisecitation

    Daily energy intake in East African runners is distributed over a small number of meals, with prolonged moderate-to fast-paced morning runs being undertaken before breakfast and with nil/minimal intake of fluid.

    “Daily energy intake is distributed over a small number of meals, with prolonged moderate-to fast-paced morning runs being undertaken before breakfast and with nil/minimal intake of fluid (Beis et al., 2011;Fudge et al., 2006Fudge et al., , 2008;;Onywera et al., 2004).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Beis et al., 2011

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    • cites Fudge et al., 2006

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    • cites Onywera et al., 2004

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Intake of reasonable amounts of cold/icy beverages might theoretically contribute to improved thermoregulation.

    “intake of reasonable amounts of cold/icy beverages might theoretically contribute to improved thermoregulation (Jay & Morris, 2018).”
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    • cites Jay & Morris, 2018

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    East African runners appear to maintain their eating practices on the competition circuit or in their Northern Hemisphere training bases because of low cost, cultural familiarity, and self-belief that it might contribute to their success.

    “it appears that they maintain their eating practices on the competition circuit or in their Northern Hemisphere training bases because of the low cost and cultural familiarity, as well as self-belief that it might contribute to their success (M.Mooses, personal observations, Dec 10, 2018).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites M.Mooses, personal observations, Dec 10, 2018

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  • May combine two claims.

    Premisenone given

    In East African runners' diets, CHO supplies 60-80% of energy, with high reliance on vegetables (80-90% of diet) rather than animal food sources (10-20%), and limited food variety.

    “CHO supplies 60-80% of energy, with high reliance on vegetables (80-90% of diet) rather than animal food sources (10-20%), and limited food variety (staple foods: rice, pasta, potatoes, porridge, cabbage, kidney beans, ugali maize meal, and injera flatbread).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Contributors to energy mismatches in East African athletes include cultural eating patterns (e.g., fiber-rich unvaried diet, few eating occasions in a day), food insecurity, and the interaction with high training loads (e.g., lack of intake during training hours, postexercise appetite suppression).

    “Contributors to energy mismatches include cultural eating patterns (e.g., fiber-rich unvaried diet, few eating occasions in a day), food insecurity, and the interaction with high training loads (e.g., lack of intake during training hours, postexercise appetite suppression; Burke et al., 2018b).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Burke et al., 2018b

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  • May combine two claims.

    Interpretationcitation

    An increase in RQ improves metabolic efficiency by reducing the O2 cost of running at a particular speed or permitting a higher speed for the same absolute VO2.

    “an increase in RQ improves metabolic efficiency by reducing the O 2 cost of running at a particular speed or permitting a higher speed for the same absolute VO 2 .”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationnone given

    An athlete with a sustainable VO2 of 3.75 L/min and running economy of 180 ml/kg/min would achieve a sustainable marathon running speed of 20.83 km/hr, with a finishing time of 2:01:33.

    “an athlete with a sustainable VO 2 of 3.75 L/min and running economy of 180 ml•kg -1 •min -1 would achieve a sustainable marathon running speed of 20.83 km/hr, with a finishing time of 2:01:33.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: Sustainable VO2 of 3.75 L/min and running economy of 180 ml/kg/min for the athlete in the example.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    It is likely that East African runners' practices include both helpful and harmful features, as well as accidental and intentional elements.

    “It is likely that practices include both helpful and harmful features, as well as accidental and intentional elements.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    In-race nutrition is dependent on practicalities, such as availability of aid stations as well as time and gut considerations of consuming CHO-containing fluids or other sports products.

    “In-race nutrition is dependent on practicalities, such as the availability of aid stations as well as time and gut considerations of consuming CHO-containing fluids or other sports products.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    A ~0.9% increase in the energy liberated per liter O2 consumed (achieved via a 0.05 unit increment in RQ, e.g., from 0.85 to 0.90) could translate into a similar magnitude of increment in running speed (to 21.02 km/hr) and a finishing time of 2:00:27, a 66 s improvement.

    “a ∼0.9% increase in the energy liberated per liter O 2 consumed (achieved via a 0.05 unit increment in RQ, e.g., from 0.85 to 0.90) could translate into a similar magnitude of increment in running speed (to 21.02 km/hr) and a finishing time of 2:00:27, a 66 s improvement.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: A 0.05 unit increment in RQ (e.g., from 0.85 to 0.90) is achievable.

  • May combine two claims.

    Interpretationreasoning

    In a hypothetical athlete with a VO2max of 80 ml/kg/min (i.e., 4.4 L/min), VO2 during the race would correspond to 3.63 L/min (or 83% VO2max) and 3.83 L/min (or 87% VO2max) using purely CHO or fat, respectively.

    “In our hypothetical athlete with a VO 2 max of 80 ml•kg -1 •min -1 (i.e., 4.4 L/min), VO 2 during the race would correspond to 3.63 L/min (or 83% VO 2 max) and 3.83 L/min (or 87% VO 2 max) using purely CHO or fat, respectively.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: VO2max of 80 ml/kg/min (4.4 L/min) for the hypothetical athlete.
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  • The paper relies on this without support.

    Lactate threshold typically occurs between 60% and 80% VO2max even in highly trained individuals.

    “However, LT typically occurs between 60% and 80% VO 2 max even in highly trained individuals; a lower intensity than this is maintained during most distance races, except perhaps the 50-km walk.”

  • The paper relies on this without support.

    Heavy training loads and habitual dietary practices of high-performance distance runners and race walkers, including East African athletes, already create periodization of carbohydrate availability across a training cycle.

    “It is likely that the heavy training loads and habitual dietary practices of high-performance distance runners/walkers, including the remarkable East African athletes (Commentary 1), already create periodization of CHO availability across a training cycle.”

  • The paper relies on this without support.

    Additional benefits of a prerace reduction in intestinal fiber content for distance runners and walkers include a lowered risk of gut discomfort or upset during the race and simplification of the logistics of bowel evacuations in the hours prior to a race.

    “Additional benefits of a prerace reduction in intestinal fiber content for distance runners and walkers include a lowered risk of gut discomfort/upset during the race and simplification of the logistics of bowel evacuations in the hours prior to a race.”

  • The paper relies on this without support.

    Disadvantages of the prerace low-fiber diet include a lack of food variety, a short-term reduction in dietary quality or micronutrient density, and discomfort due to lower satiety or hunger.

    “Disadvantages of the prerace low-fiber diet include a lack of food variety, a (short-term) reduction in dietary quality/ micronutrient density and discomfort due to lower satiety/hunger.”

  • The paper relies on this without support.

    The low-fiber diet can be integrated with a carbohydrate-loading protocol and may assist with achieving targets for large amounts of carbohydrate intake due to the increased energy density of food choices.

    “The diet can be integrated with a carbohydrate-loading protocol and may even assist with the achievement of targets for large amounts of carbohydrate intake due to the increased energy density of food choices.”

  • The paper relies on this without support.

    Some recent elite marathons, including the 2018 Berlin event, have increased the frequency of feed zones to every 2.5 km to provide greater opportunity for race feeding.

    “Indeed, some recent elite marathons, including the 2018 Berlin event in which the most recent world record was set, have increased the frequency of feed zones (every 2.5 km) to provide greater opportunity for race feeding.”

  • The paper relies on this without support.

    The implementation and outcomes of low-fiber diets have not been subjected to rigorous scientific investigation in sporting scenarios.

    “The implementation and outcomes have not been subjected to rigorous scientific investigation in sporting scenarios.”

  • The authors state this as an assumption.

    Running economy of 190 ml/kg/km at 21.1 km/hr for the hypothetical marathon runner.

    “if we assume a running economy of 190 ml•kg -1 •km -1 at 21.1 km/hr”

  • The authors state this as an assumption.

    Body mass of 55 kg for the hypothetical marathon runner.

    “BM of 55 kg”

  • The authors state this as an assumption.

    VO2max of 80 ml/kg/min (4.4 L/min) for the hypothetical athlete.

    “In our hypothetical athlete with a VO 2 max of 80 ml•kg -1 •min -1 (i.e., 4.4 L/min)”

  • The authors state this as an assumption.

    Sustainable VO2 of 3.75 L/min and running economy of 180 ml/kg/min for the athlete in the example.

    “an athlete with a sustainable VO 2 of 3.75 L/min and running economy of 180 ml•kg -1 •min -1”

  • The authors state this as an assumption.

    A 0.05 unit increment in RQ (e.g., from 0.85 to 0.90) is achievable.

    “achieved via a 0.05 unit increment in RQ, e.g., from 0.85 to 0.90”

  • The paper relies on this without support.

    Glycerol has been removed from WADA's list of prohibited substances and may be reinstated for use in hyperhydration/rehydration strategies.

    “glycerol has been removed from the World Anti-Doping Agency's list of prohibited substances and may be reinstated for use in hyperhydration/rehydration strategies.”

  • The paper relies on this without support.

    Meals are consumed soon after training sessions, and high-intensity track sessions are completed as a midmorning workout after breakfast.

    “Meanwhile, meals are consumed soon after training sessions, and high-intensity track sessions are completed as a midmorning workout after breakfast.”
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Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Claim that most races are below lactate threshold conflicts with Table 1

    Minor

    The text says most distance races are run below the stated 60-80% VO2 max lactate-threshold range, except perhaps the 50-km walk. Table 1 instead lists the other events at approximately 80-95% VO2 max.

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Authors
Burke, L. M., Jeukendrup, A. E., Jones, A. M., & Mooses, M.
Affiliations
Loughborough University (GB)
Corresponding author
Burke, Louise M.
ORCID
Venue
International Journal of Sport Nutrition and Exercise Metabolism
Publisher
Human Kinetics
Published
2019-03-01
Volume
29
Issue
2
Pages
117-129
ISSN
  • 1526-484X (ISSN-L)
  • 1543-2742
DOI
10.1123/ijsnem.2019-0004
OpenAlex
W2914687771
Cited by
170
References
99
Citations by year
2026: 21 · 2025: 20 · 2024: 35 · 2023: 19 · 2022: 21 · 2021: 21 · 2020: 21 · 2019: 11 · 2018: 1
FWCI
3.52
Type
journal article
Language
en
Open access
Locations
  • International Journal of Sport Nutrition and Exercise Metabolism (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Physiology › Thermoregulation and physiological responses
Keywords
long-distance running, race walking, carbohydrate intake, glycogen storage, hydration, fluid intake, mouthwash, sports drinks, caffeine supplementation, nitrate supplementation, half marathon, cross country, running economy
MeSH terms
Adaptation, Physiological, Dietary Carbohydrates, Humans, Nutritional Requirements, Running, Walking, Athletic Performance, Athletes, Performance-Enhancing Substances, Sports Nutritional Physiological Phenomena

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Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

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