Increased cardiorespiratory stress during submaximal cycling after ketone monoester ingestion in endurance-trained adults

McCarthy, Devin G.; Bostad, William; Powley, Fiona J.; Little, Jonathan P.; Richards, Douglas L.; Gibala, Martin J.

doi:10.1139/apnm-2020-0999

Cited by 16 publications

(65 citation statements)

References 52 publications

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“…Such an increase in PO 2 after ketone body exposure has also previously been observed in rodents after administration of 1,3-butanediol acetoacetate ketone diester during hyperbaric oxygen exposure (59). Furthermore, in line with earlier observations from our (41) and other (60) laboratories in normoxia, KE increased the hypoxic ventilatory response. This was mediated by an increase in both breathing frequency and tidal volume.…”

Section: Discussionsupporting

confidence: 91%

Exogenous ketosis increases blood and muscle oxygenation but not performance during exercise in hypoxia

Poffé

Robberechts

Podlogar

et al. 2021

American Journal of Physiology-Regulatory, Integrative and Comp

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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 3h 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 (FiO2) was gradually decreased from 18.6 to 14.5%. Before and during RACE, participants received either i) 75g ketone ester (KE), ii) 300 mg/kg body mass bicarbonate (BIC), iii) KE+BIC or iv) a control drink in addition to 60g carbohydrates per h in a randomized, crossover design. KE counteracted the hypoxia-induced drop in blood (SpO2) and muscle oxygenation by ~3%. In contrast, BIC decreased SpO2 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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Section: Discussionsupporting

confidence: 91%

Exogenous ketosis increases blood and muscle oxygenation but not performance during exercise in hypoxia

Poffé

Robberechts

Podlogar

et al. 2021

American Journal of Physiology-Regulatory, Integrative and Comp

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“…1), including being fasted or fed, and being at rest or exercising, such that large variations exist in the degree of ketosis (Table 1). Ingestion of EKS, therefore, provides an alternative method to increase [R-βHB], and to a lesser extent [AcAc] [34][35][36][37][38][39], without injections or intravenous infusions [40], both of which would be impractical or illegal in most athletic contexts.…”

Section: Introductionmentioning

confidence: 99%

Exogenous Ketone Supplements in Athletic Contexts: Past, Present, and Future

Evans

McClure²,

Koutnik³

et al. 2022

Sports Med

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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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“…Furthermore, ingestion of a KME also increased RPE (PLA, 4 ± 1; KME, 6 ± 1) following the live-burn S&R compared with PLA alone. Generally, RPE has been reported to be similar between KME and PLA conditions in previous exercise studies (9,10,31), but elevated RPE during exercise with nutritional ketosis produced by diet (46) or KME ingestion (23,30) has also been observed. For example, White et al (2007) observed a positive correlation ( r = 0.47) between elevated βHB concentrations and increased subjective states of RPE during submaximal exercise.…”

Section: Discussionmentioning

confidence: 86%

“…These findings have implications in the FF cohort, where an increase in exercise efficiency and subsequent preservation of oxygen stores can result in a FF prolong their time completing a victim S&R before exiting a burning building. However, in contrast to these data, one study recently observed an increase in exercising HR following ingestion of a KME (23). Indeed, there remains discrepancies regarding the impact that bHB might have on cardiorespiratory measures, such as HR.…”

Section: Discussionmentioning

confidence: 86%

No Effect of a Ketone Monoester on Markers of Stress and Performance in a Live-Burn Search and Rescue in Firefighters

Waldman

Bryant

Shepherd

et al. 2022

Journal of Strength and Conditioning Research

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Waldman, HS, Bryant, AR, Shepherd, BD, Egan, B, and 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 36(3): 763-771, 2022-Firefighters experience a range of stressors that impair performance and elevate the risk for developing cardiometabolic diseases. b-Hydroxybutyrate (bHB) has been shown to mitigate markers of oxidative stress and inflammation and serve as an alternative fuel with implications to physical performance. On 2 occasions in a double-blind, counterbalanced, and crossover design, 14 professional firefighters performed a live-burn, search and rescue (S&R) 30 minutes after ingestion of a ketone monoester (KME; 0.5 g•kg 21 ) or a placebo (PLA). Dependent variables collected before and after the S&R included salivary markers of stress and inflammation (cortisol, a-amylase, interleukin-1 beta, uric acid), perceptual markers (profile of mood state [POMS]), gastrointestinal distress (GI), rating of perceived exertion [RPE]), time to completion, and capillary blood measurement of bHB and glucose. KME resulted in capillary bHB concentrations of approximately 2.1-3.2 mM throughout the protocol. Capillary glucose concentrations were lower for the KME compared with PLA (;7%) (interaction effect, p , 0.001). Salivary markers of stress, GI, and time to complete the S&R (;10 minutes) did not differ between trials, although KME ingestion resulted in significantly higher RPE after the live-burn S&R (KME,6 6 1; PLA, 4 6 1). However, POMS data showed the KME also lowered subjective states of nervousness (KME, 0.0 6 0.0; PLA, 0.6 6 0.8) and anxiety (KME, 0.0 6 0.0; PLA, 0.6 6 0.7) before the S&R (all p , 0.05; large effect sizes). Compared with PLA, ingestion of a KME by firefighters did not mitigate the rise in various markers of salivary stress or impact physical performance during a live-burn S&R. However, differences in RPE and POMS variables were observed, suggesting a possible cognitive role for bHB.

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Increased cardiorespiratory stress during submaximal cycling after ketone monoester ingestion in endurance-trained adults

Cited by 16 publications

References 52 publications

Exogenous ketosis increases blood and muscle oxygenation but not performance during exercise in hypoxia

Exogenous ketosis increases blood and muscle oxygenation but not performance during exercise in hypoxia

Exogenous Ketone Supplements in Athletic Contexts: Past, Present, and Future

No Effect of a Ketone Monoester on Markers of Stress and Performance in a Live-Burn Search and Rescue in Firefighters

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