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Waldman HS, O'Neal EK, Barker GA, Witt CR, Lara DA, Huber AK, Forsythe VN, Koutnik AP, D'Agostino DP, Staiano W, Egan B. A Ketone Monoester with Carbohydrate Improves Cognitive Measures Postexercise, but Not Performance in Trained Females. Med Sci Sports Exerc 2024; 56:725-736. [PMID: 38051034 DOI: 10.1249/mss.0000000000003352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
PURPOSE The acute ingestion of a ketone monoester with the coingestion of a carbohydrate (KME + CHO) compared with carbohydrate (CHO) was investigated on cycling performance and cognitive performance in trained females. METHODS Using a two condition, placebo-controlled, double-blinded and crossover design, 12 trained females (mean ± SD: age, 23 ± 3 yr; height, 1.64 ± 0.08 m; mass, 65.2 ± 12.7 kg) completed a baseline assessment of cognitive performance (psychomotor vigilance testing (PVT), task switching, and incongruent flanker), followed by 6 × 5-min intervals at 40%, 45%, 50%, 55%, 60%, and 65% of their maximal power output (W max ) and then a 10-km time trial, concluding with the same assessments of cognitive performance. Participants consumed either 375 mg·kg -1 body mass of KME with a 6% CHO solution (1 g·min -1 of exercise) or CHO alone, across three boluses (50:25:25). RESULTS Blood β-hydroxybutyrate concentrations averaged 1.80 ± 0.07 and 0.13 ± 0.01 mM during exercise in KME + CHO and CHO, respectively. Blood glucose decreased after drink 1 of KME + CHO (~15%; P = 0.01) but not CHO, and lactate concentrations were lower in KME + CHO at 50%, 55%, 60%, and 65% W max (all P < 0.05) compared with CHO. Despite these changes, no differences were found between conditions for time trial finishing times (KME + CHO, 29.7 ± 5.7 min; CHO, 29.6 ± 5.7 min; P = 0.92). However, only KME + CHO resulted in increases in psychomotor vigilance testing speed (~4%; P = 0.01) and faster reaction times (~14%; P < 0.01), speed (~15%; P < 0.01), and correct responses (~13%; P = 0.03) in the incongruent flanker during posttesting compared with CHO. CONCLUSIONS The acute ingestion of a KME + CHO elevated blood β-hydroxybutyrate and lowered glucose and lactate across multiple time points during exercise compared with CHO. Although these changes did not affect physical performance, several markers of cognitive performance were improved by the addition of a KME in trained females.
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Affiliation(s)
- Hunter S Waldman
- Department of Kinesiology, University of North Alabama, Florence, AL
| | - Eric K O'Neal
- Department of Kinesiology, University of North Alabama, Florence, AL
| | - Gaven A Barker
- Department of Kinesiology, University of North Alabama, Florence, AL
| | - Craig R Witt
- Department of Kinesiology, University of North Alabama, Florence, AL
| | - David A Lara
- Department of Kinesiology, University of North Alabama, Florence, AL
| | - Anna K Huber
- Department of Kinesiology, University of North Alabama, Florence, AL
| | | | | | | | - Walter Staiano
- Department of Physical Education and Sport, University of Valencia, Valencia, SPAIN
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Valenzuela PL, Santalla A, Alejo LB, Bustos A, Ozcoidi LM, Castellote-Bellés L, Ferrer-Costa R, Villarreal-Salazar M, Morán M, Barranco-Gil D, Pinós T, Lucia A. Acute ketone supplementation in the absence of muscle glycogen utilization: Insights from McArdle disease. Clin Nutr 2024; 43:692-700. [PMID: 38320460 DOI: 10.1016/j.clnu.2024.01.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 01/10/2024] [Accepted: 01/23/2024] [Indexed: 02/08/2024]
Abstract
BACKGROUND & AIMS Ketone supplementation is gaining popularity. Yet, its effects on exercise performance when muscle glycogen cannot be used remain to be determined. McArdle disease can provide insight into this question, as these patients are unable to obtain energy from muscle glycogen, presenting a severely impaired physical capacity. We therefore aimed to assess the effects of acute ketone supplementation in the absence of muscle glycogen utilization (McArdle disease). METHODS In a randomized cross-over design, patients with an inherited block in muscle glycogen breakdown (i.e., McArdle disease, n = 8) and healthy controls (n = 7) underwent a submaximal (constant-load) test that was followed by a maximal ramp test, after the ingestion of a placebo or an exogenous ketone ester supplement (30 g of D-beta hydroxybutyrate/D 1,3 butanediol monoester). Patients were also assessed after carbohydrate (75 g) ingestion, which is currently considered best clinical practice in McArdle disease. RESULTS Ketone supplementation induced ketosis in all participants (blood [ketones] = 3.7 ± 0.9 mM) and modified some gas-exchange responses (notably increasing respiratory exchange ratio, especially in patients). Patients showed an impaired exercise capacity (-65 % peak power output (PPO) compared to controls, p < 0.001) and ketone supplementation resulted in a further impairment (-11.6 % vs. placebo, p = 0.001), with no effects in controls (p = 0.268). In patients, carbohydrate supplementation resulted in a higher PPO compared to ketones (+21.5 %, p = 0.001) and a similar response was observed vs. placebo (+12.6 %, p = 0.057). CONCLUSIONS In individuals who cannot utilize muscle glycogen but have a preserved ability to oxidize blood-borne glucose and fat (McArdle disease), acute ketone supplementation impairs exercise capacity, whereas carbohydrate ingestion exerts the opposite, beneficial effect.
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Affiliation(s)
- Pedro L Valenzuela
- Physical Activity and Health Research Group ('PaHerg'), Research Institute of Hospital '12 de Octubre' ('imas12'), Madrid, Spain; Department of Systems Biology, University of Alcalá, Madrid, Spain.
| | - Alfredo Santalla
- Department of Sport and Computer Science, Section of Physical Education and Sports, Faculty of Sport, Universidad Pablo de Olavide, Sevilla, Spain; EVOPRED Research Group, Universidad Europea de Canarias, Tenerife, Spain
| | - Lidia B Alejo
- Physical Activity and Health Research Group ('PaHerg'), Research Institute of Hospital '12 de Octubre' ('imas12'), Madrid, Spain; Faculty of Sport Sciences, Universidad Europea de Madrid, Madrid, Spain
| | - Asunción Bustos
- Faculty of Sport Sciences, Universidad Europea de Madrid, Madrid, Spain
| | - Laureano M Ozcoidi
- Hospital Reina Sofía de Tudela, Servicio Navarro de Salud, Navarra, Spain
| | - Laura Castellote-Bellés
- Department of Clinical Biochemistry, Laboratoris Clínics, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Roser Ferrer-Costa
- Department of Clinical Biochemistry, Laboratoris Clínics, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Mónica Villarreal-Salazar
- Mitochondrial and Neuromuscular Disorders Unit, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain; Spanish Network for Biomedical Research in Rare Diseases (CIBERER), U723, Madrid, Spain
| | - María Morán
- Spanish Network for Biomedical Research in Rare Diseases (CIBERER), U723, Madrid, Spain; Mitochondrial and Neuromuscular Diseases Laboratory, Research Institute of Hospital 12 de Octubre (imas12), Madrid, Spain
| | | | - Tomàs Pinós
- Mitochondrial and Neuromuscular Disorders Unit, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain; Spanish Network for Biomedical Research in Rare Diseases (CIBERER), U723, Madrid, Spain.
| | - Alejandro Lucia
- Faculty of Sport Sciences, Universidad Europea de Madrid, Madrid, Spain
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Brady AJ, Egan B. Acute Ingestion of a Ketone Monoester without Co-ingestion of Carbohydrate Improves Running Economy in Male Endurance Runners. Med Sci Sports Exerc 2024; 56:134-142. [PMID: 37565450 DOI: 10.1249/mss.0000000000003278] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
PURPOSE Acute ingestion of a ketone monoester, with and without co-ingestion of carbohydrate, was investigated for effects on running economy (RE), time to exhaustion (TTE), and other related indices of endurance running performance. METHODS Using a three condition, placebo-controlled, randomized crossover design, 11 male middle- and long-distance runners ran at five submaximal speeds (10-14 km·h -1 ) on a motorized treadmill for 8 min each, immediately followed by a ramp test to volitional exhaustion. Participants consumed either a 10% carbohydrate solution (CHO), a 10% carbohydrate solution with 750 mg·kg -1 body mass of an ( R )-3-hydroxybutyl ( R )-3-hydroxybutyrate ketone monoester (CHO + KE), or 750 mg·kg -1 body mass of the ketone monoester in flavored water (KE) before (two-thirds of the dose) and during (one-third of the dose) exercise. RESULTS β-hydroxybutyrate concentration averaged 1.8 ± 0.3 and 2.1 ± 0.3 mM during exercise in CHO + KE and KE, respectively. RE was lower at each submaximal running speed (effect size = 0.48-0.98) by an average of 4.1% in KE compared with CHO, but not between CHO + KE and CHO. TTE did not differ between CHO (369 ± 116 s), CHO + KE (342 ± 99 s), or KE (333 ± 106 s) ( P = 0.093). CONCLUSIONS Acute ingestion of a ketone monoester without carbohydrate, but not when coingested with carbohydrate, improved RE in middle- and long-distance runners at a range of submaximal running speeds and did not alter TTE in a short-duration ramp test to volitional exhaustion. Further investigation is required to examine if these differences translate into positive performance outcomes over longer durations of exercise.
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Margolis LM, Pasiakos SM, Howard EE. High-fat ketogenic diets and ketone monoester supplements differentially affect substrate metabolism during aerobic exercise. Am J Physiol Cell Physiol 2023; 325:C1144-C1153. [PMID: 37721006 PMCID: PMC10635661 DOI: 10.1152/ajpcell.00359.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/07/2023] [Accepted: 09/07/2023] [Indexed: 09/19/2023]
Abstract
Chronically adhering to high-fat ketogenic diets or consuming ketone monoester supplements elicits ketosis. Resulting changes in substrate metabolism appear to be drastically different between ketogenic diets and ketone supplements. Consuming a ketogenic diet increases fatty acid oxidation with concomitant decreases in endogenous carbohydrate oxidation. Increased fat oxidation eventually results in an accumulation of circulating ketone bodies, which are metabolites of fatty acids that serve as an alternative source of fuel. Conversely, consuming ketone monoester supplements rapidly increases circulating ketone body concentrations that typically exceed those achieved by adhering to ketogenic diets. Rapid increases in ketone body concentrations with ketone monoester supplementation elicit a negative feedback inhibition that reduces fatty acid mobilization during aerobic exercise. Supplement-derived ketosis appears to have minimal impact on sparing of muscle glycogen or minimizing of carbohydrate oxidation during aerobic exercise. This review will discuss the substrate metabolic and associated aerobic performance responses to ketogenic diets and ketone supplements.
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Affiliation(s)
- Lee M Margolis
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Stefan M Pasiakos
- Office of Dietary Supplements, U.S. Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland, United States
| | - Emily E Howard
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
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McCarthy DG, Bostad W, Bone J, Powley FJ, Richards DL, Gibala MJ. Effect of Acute Ketone Monoester Ingestion on Cardiorespiratory Responses to Exercise and the Influence of Blood Acidosis. Med Sci Sports Exerc 2023; 55:1286-1295. [PMID: 36849121 DOI: 10.1249/mss.0000000000003141] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
PURPOSE This study aimed to examine the effect of KE ingestion on exercise cardiac output ( Q˙ ) and the influence of blood acidosis. We hypothesized that KE versus placebo ingestion would increase Q ˙, and coingestion of the pH buffer bicarbonate would mitigate this effect. METHODS In a randomized, double-blind, crossover manner, 15 endurance-trained adults (peak oxygen uptake (V̇O 2peak ), 60 ± 9 mL·kg -1 ·min -1 ) ingested either 0.2 g·kg -1 sodium bicarbonate or a salt placebo 60 min before exercise, and 0.6 g·kg -1 KE or a ketone-free placebo 30 min before exercise. Supplementation yielded three experimental conditions: basal ketone bodies and neutral pH (CON), hyperketonemia and blood acidosis (KE), and hyperketonemia and neutral pH (KE + BIC). Exercise involved 30 min of cycling at ventilatory threshold intensity, followed by determinations of V̇O 2peak and peak Q ˙. RESULTS Blood [β-hydroxybutyrate], a ketone body, was higher in KE (3.5 ± 0.1 mM) and KE + BIC (4.4 ± 0.2) versus CON (0.1 ± 0.0, P < 0.0001). Blood pH was lower in KE versus CON (7.30 ± 0.01 vs 7.34 ± 0.01, P < 0.001) and KE + BIC (7.35 ± 0.01, P < 0.001). Q ˙ during submaximal exercise was not different between conditions (CON: 18.2 ± 3.6, KE: 17.7 ± 3.7, KE + BIC: 18.1 ± 3.5 L·min -1 ; P = 0.4). HR was higher in KE (153 ± 9 bpm) and KE + BIC (154 ± 9) versus CON (150 ± 9, P < 0.02). V̇O 2peak ( P = 0.2) and peak Q ˙ ( P = 0.3) were not different between conditions, but peak workload was lower in KE (359 ± 61 W) and KE + BIC (363 ± 63) versus CON (375 ± 64, P < 0.02). CONCLUSIONS KE ingestion did not increase Q ˙ during submaximal exercise despite a modest elevation of HR. This response occurred independent of blood acidosis and was associated with a lower workload at V̇O 2peak .
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Affiliation(s)
- Devin G McCarthy
- Department of Kinesiology, McMaster University, Hamilton, ON, CANADA
| | - William Bostad
- Department of Kinesiology, McMaster University, Hamilton, ON, CANADA
| | - Jack Bone
- Department of Kinesiology, McMaster University, Hamilton, ON, CANADA
| | - Fiona J Powley
- Department of Kinesiology, McMaster University, Hamilton, ON, CANADA
| | | | - Martin J Gibala
- Department of Kinesiology, McMaster University, Hamilton, ON, CANADA
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Howard EE, Allen JT, Coleman JL, Small SD, Karl JP, O'Fallon KS, Margolis LM. Ketone Monoester Plus Carbohydrate Supplementation Does Not Alter Exogenous and Plasma Glucose Oxidation or Metabolic Clearance Rate During Exercise in Men Compared with Carbohydrate Alone. J Nutr 2023:S0022-3166(23)35281-7. [PMID: 36893935 DOI: 10.1016/j.tjnut.2023.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/21/2023] [Accepted: 03/01/2023] [Indexed: 03/11/2023] Open
Abstract
BACKGROUND Increasing β-hydroxybutyrate (βHB) availability through ketone monoester plus carbohydrate (KE+CHO) supplementation is suggested to enhance physical performance by sparing glucose use during exercise. However, no studies have examined the effect of ketone supplementation on glucose kinetics during exercise. OBJECTIVES This exploratory study primarily aimed to determine the effect of KE+CHO supplementation on glucose oxidation and physical performance during steady-state exercise compared with carbohydrate. METHODS Using a randomly assigned, crossover design (clinicaltrials.gov, NCT04737694), 12 men consumed KE+CHO (573 mg ketone monoester/kg body mass, 110 g glucose) or carbohydrate (110 g glucose) before and during 90 min of steady-state treadmill exercise [54 ± 3% peak oxygen uptake (V̇˙O2peak)] wearing a weighted vest (30% body mass; 25 ± 3 kg). Glucose oxidation and turnover were determined using indirect calorimetry and stable isotopes. Participants performed an unweighted time to exhaustion (TTE; 85% V̇˙O2peak) after steady-state exercise and a weighted (25 ± 3 kg) 6.4 km time trial (TT) the next day after consuming a bolus of KE+CHO or carbohydrate. Data were analyzed by paired t-tests and mixed model ANOVA. RESULTS βHB concentrations were higher (P < 0.05) after exercise [2.1 mM (95% CI: 1.6, .6)] and the TT [2.6 mM (2.1, 3.1)] in KE+CHO compared with carbohydrate. TTE was lower [-104 s (-201, -8)], and TT performance was slower [141 s (19,262)] in KE+CHO than in carbohydrate (P < 0.05). Exogenous [-0.01 g/min (-0.07, 0.04)] and plasma [-0.02 g/min (-0.08, 0.04)] glucose oxidation and metabolic clearance rate {MCR [0.38 mg·kg-1·min-1 (-0.79, 1.54)]} were not different, and glucose rate of appearance [-0.51 mg·kg-1·min-1 (-0.97, -0.04)], and disappearance [-0.50 mg·kg-1·min-1 (-0.96, -0.04)] were lower (P < 0.05) in KE+CHO compared with carbohydrate during steady-state exercise. CONCLUSIONS In the current study, the rates of exogenous and plasma glucose oxidation and MCR were not different between treatments during steady-state exercise, suggesting blood glucose utilization is similar between KE+CHO and carbohydrate. KE+CHO supplementation also results in lower physical performance compared with carbohydrate. This trial was registered at www. CLINICALTRIALS gov as NCT04737694.
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Affiliation(s)
- Emily E Howard
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States
| | - Jillian T Allen
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States
| | - Julie L Coleman
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States; Oak Ridge Institute for Science and Education, Oak Ridge, TN, United States
| | - Stephanie D Small
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States; Oak Ridge Institute for Science and Education, Oak Ridge, TN, United States; Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - J Philip Karl
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States
| | - Kevin S O'Fallon
- Soldier Effectiveness Directorate, United States Army Combat Capabilities Development Command Soldier Center, Natick, MA, United States
| | - Lee M Margolis
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States.
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Falkenhain K, Islam H, Little JP. Exogenous ketone supplementation: an emerging tool for physiologists with potential as a metabolic therapy. Exp Physiol 2023; 108:177-187. [PMID: 36533967 PMCID: PMC10103874 DOI: 10.1113/ep090430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022]
Abstract
NEW FINDINGS What is the topic of this review? The integrative physiological response to exogenous ketone supplementation. What advances does it highlight? The physiological effects and therapeutic potential of exogenous ketones on metabolic health, cardiovascular function, cognitive processing, and modulation of inflammatory pathways and immune function. Also highlighted are current challenges and future directions of the field. ABSTRACT Exogenous oral ketone supplements, primarily in form of ketone salts or esters, have emerged as a useful research tool for manipulating metabolism with potential therapeutic application targeting various aspects of several common chronic diseases. Recent literature has investigated the effects of exogenously induced ketosis on metabolic health, cardiovascular function, cognitive processing, and modulation of inflammatory pathways and immune function. This narrative review provides an overview of the integrative physiological effects of exogenous ketone supplementation and highlights current challenges and future research directions. Much of the existing research on therapeutic applications - particularly mechanistic studies - has involved pre-clinical rodent and/or cellular models, requiring further validation in human clinical studies. Existing human studies report that exogenous ketones can lower blood glucose and improve some aspects of cognitive function, highlighting the potential therapeutic application of exogenous ketones for type 2 diabetes and neurological diseases. There is also support for the ability of exogenous ketosis to improve cardiac metabolism in rodent models of heart failure with supporting human studies emerging; long-terms effects of exogenous ketone supplementation on the human cardiovascular system and lipid profiles are needed. An important avenue for future work is provided by research accelerating technologies that enable continuous ketone monitoring and/or the development of more palatable ketone mixtures that optimize plasma ketone kinetics to enable sustained ketosis. Lastly, research exploring the physiological interactions between exogenous ketones and varying metabolic states (e.g., exercise, fasting, metabolic disease) should yield important insights that can be used to maximize the health benefits of exogenous ketosis.
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Affiliation(s)
- Kaja Falkenhain
- School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaBritish ColumbiaCanada
| | - Hashim Islam
- School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaBritish ColumbiaCanada
| | - Jonathan P. Little
- School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaBritish ColumbiaCanada
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Falkenhain K, Daraei A, Forbes SC, Little JP. Effects of Exogenous Ketone Supplementation on Blood Glucose: A Systematic Review and Meta-analysis. Adv Nutr 2022; 13:1697-1714. [PMID: 35380602 PMCID: PMC9526861 DOI: 10.1093/advances/nmac036] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 03/04/2022] [Accepted: 04/01/2022] [Indexed: 01/28/2023] Open
Abstract
Recently developed ketone (monoester or salt) supplements acutely elevate blood β-hydroxybutyrate (BHB) exogenously without prolonged periods of fasting or carbohydrate restriction. Previous (small-scale) studies have found a blood glucose-lowering effect of exogenous ketones. This study aimed to systematically review available evidence and conduct meta-analyses of studies reporting on exogenous ketones and blood glucose. We searched 6 electronic databases on 13 December 2021 for randomized and nonrandomized trials of any length that reported on the use of exogenous ketones. We calculated raw mean differences (MDs) in blood BHB and glucose in 2 main analyses: 1) after compared with before acute ingestion of exogenous ketones and 2) following acute ingestion of exogenous ketones compared with a comparator supplement. We pooled effect sizes using random-effects models and performed prespecified subgroup analyses to examine the effect of potential explanatory factors, including study population, exercise, blood BHB, and supplement type, dosing, and timing. Risk of bias was examined using Cochrane's risk-of-bias tools. Studies that could not be meta-analyzed were summarized narratively. Forty-three trials including 586 participants are summarized in this review. Following ingestion, exogenous ketones increased blood BHB (MD = 1.73 mM; 95% CI: 1.26, 2.21 mM; P < 0.001) and decreased mean blood glucose (MD = -0.54 mM; 95% CI: -0.68, -0.40 mM; P < 0.001). Similarly, when compared with placebo, blood BHB increased (MD = 1.98 mM; 95% CI: 1.52, 2.45 mM; P < 0.001) and blood glucose decreased (MD = -0.47 mM; 95% CI: -0.57, -0.36 mM; P < 0.001). Across both analyses, significantly greater effects were seen with ketone monoesters compared with salts (P < 0.001). The available evidence indicates that acute ingestion of exogenous ketones leads to increased blood BHB and decreased blood glucose. Limited evidence on prolonged ketone supplementation was found.
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Affiliation(s)
| | - Ali Daraei
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Scott C Forbes
- Department of Physical Education Studies, Faculty of Education, Brandon University, Brandon, Manitoba, Canada
| | - Jonathan P Little
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Waldman HS, Bryant AR, Shepherd BD, Egan B, McAllister MJ. No Effect of a Ketone Monoester on Markers of Stress and Performance in a Live-Burn Search and Rescue in Firefighters. J Strength Cond Res 2022; 36:763-771. [DOI: 10.1519/jsc.0000000000004194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Factors Influencing Substrate Oxidation During Submaximal Cycling: A Modelling Analysis. Sports Med 2022; 52:2775-2795. [PMID: 35829994 PMCID: PMC9585001 DOI: 10.1007/s40279-022-01727-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2022] [Indexed: 02/01/2023]
Abstract
BACKGROUND Multiple factors influence substrate oxidation during exercise including exercise duration and intensity, sex, and dietary intake before and during exercise. However, the relative influence and interaction between these factors is unclear. OBJECTIVES Our aim was to investigate factors influencing the respiratory exchange ratio (RER) during continuous exercise and formulate multivariable regression models to determine which factors best explain RER during exercise, as well as their relative influence. METHODS Data were extracted from 434 studies reporting RER during continuous cycling exercise. General linear mixed-effect models were used to determine relationships between RER and factors purported to influence RER (e.g., exercise duration and intensity, muscle glycogen, dietary intake, age, and sex), and to examine which factors influenced RER, with standardized coefficients used to assess their relative influence. RESULTS The RER decreases with exercise duration, dietary fat intake, age, VO2max, and percentage of type I muscle fibers, and increases with dietary carbohydrate intake, exercise intensity, male sex, and carbohydrate intake before and during exercise. The modelling could explain up to 59% of the variation in RER, and a model using exclusively easily modified factors (exercise duration and intensity, and dietary intake before and during exercise) could only explain 36% of the variation in RER. Variables with the largest effect on RER were sex, dietary intake, and exercise duration. Among the diet-related factors, daily fat and carbohydrate intake have a larger influence than carbohydrate ingestion during exercise. CONCLUSION Variability in RER during exercise cannot be fully accounted for by models incorporating a range of participant, diet, exercise, and physiological characteristics. To better understand what influences substrate oxidation during exercise further research is required on older subjects and females, and on other factors that could explain additional variability in RER.
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Exogenous Ketone Supplements in Athletic Contexts: Past, Present, and Future. Sports Med 2022; 52:25-67. [PMID: 36214993 PMCID: PMC9734240 DOI: 10.1007/s40279-022-01756-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2022] [Indexed: 12/15/2022]
Abstract
The ketone bodies acetoacetate (AcAc) and β-hydroxybutyrate (βHB) have pleiotropic effects in multiple organs including brain, heart, and skeletal muscle by serving as an alternative substrate for energy provision, and by modulating inflammation, oxidative stress, catabolic processes, and gene expression. Of particular relevance to athletes are the metabolic actions of ketone bodies to alter substrate utilisation through attenuating glucose utilisation in peripheral tissues, anti-lipolytic effects on adipose tissue, and attenuation of proteolysis in skeletal muscle. There has been long-standing interest in the development of ingestible forms of ketone bodies that has recently resulted in the commercial availability of exogenous ketone supplements (EKS). These supplements in the form of ketone salts and ketone esters, in addition to ketogenic compounds such as 1,3-butanediol and medium chain triglycerides, facilitate an acute transient increase in circulating AcAc and βHB concentrations, which has been termed 'acute nutritional ketosis' or 'intermittent exogenous ketosis'. Some studies have suggested beneficial effects of EKS to endurance performance, recovery, and overreaching, although many studies have failed to observe benefits of acute nutritional ketosis on performance or recovery. The present review explores the rationale and historical development of EKS, the mechanistic basis for their proposed effects, both positive and negative, and evidence to date for their effects on exercise performance and recovery outcomes before concluding with a discussion of methodological considerations and future directions in this field.
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Poffé C, Robberechts R, Podlogar T, Kusters M, Debevec T, Hespel P. Exogenous ketosis increases blood and muscle oxygenation but not performance during exercise in hypoxia. Am J Physiol Regul Integr Comp Physiol 2021; 321:R844-R857. [PMID: 34668436 DOI: 10.1152/ajpregu.00198.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Available evidence indicates that elevated blood ketones are associated with improved hypoxic tolerance in rodents. From this perspective, we hypothesized that exogenous ketosis by oral intake of the ketone ester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KE) may induce beneficial physiological effects during prolonged exercise in acute hypoxia. As we recently demonstrated KE to deplete blood bicarbonate, which per se may alter the physiological response to hypoxia, we evaluated the effect of KE both in the presence and absence of bicarbonate intake (BIC). Fourteen highly trained male cyclists performed a simulated cycling race (RACE) consisting of 3-h intermittent cycling (IMT180') followed by a 15-min time-trial (TT15') and an all-out sprint at 175% of lactate threshold (SPRINT). During RACE, fraction of inspired oxygen ([Formula: see text]) was gradually decreased from 18.6% to 14.5%. Before and during RACE, participants received either 1) 75 g of ketone ester (KE), 2) 300 mg/kg body mass bicarbonate (BIC), 3) KE + BIC, or 4) a control drink in addition to 60 g of carbohydrates/h in a randomized, crossover design. KE counteracted the hypoxia-induced drop in blood ([Formula: see text]) and muscle oxygenation by ∼3%. In contrast, BIC decreased [Formula: see text] by ∼2% without impacting muscle oxygenation. Performance during TT15' and SPRINT were similar between all conditions. In conclusion, KE slightly elevated the degree of blood and muscle oxygenation during prolonged exercise in moderate hypoxia without impacting exercise performance. Our data warrant to further investigate the potential of exogenous ketosis to improve muscular and cerebral oxygenation status, and exercise tolerance in extreme hypoxia.
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Affiliation(s)
- Chiel Poffé
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Ruben Robberechts
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Tim Podlogar
- Department for Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.,Faculty of Health Sciences, University of Primorska, Izola, Slovenia
| | - Martijn Kusters
- Bakala Academy-Athletic Performance Center, KU Leuven, Leuven, Belgium
| | - Tadej Debevec
- Department for Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.,Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
| | - Peter Hespel
- Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium.,Bakala Academy-Athletic Performance Center, KU Leuven, Leuven, Belgium
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