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Nutritional Ketoacidosis During Incremental Exercise in Healthy Athletes.

ABSTRACT: Purpose: Ketosis, achieved through ingestion of ketone esters, may influence endurance exercise capacity by altering substrate metabolism. However, the effects of ketone consumption on acid-base status and subsequent metabolic and respiratory compensations are poorly described. Methods: Twelve athletically trained individuals completed an incremental bicycle ergometer exercise test to exhaustion following the consumption of either a ketone ester [(R)-3-hydroxybutyrate-(R)-1,3-butanediol] or a taste-matched control drink (bitter flavoured water) in a blinded, cross-over study. Respiratory gases and arterialised blood gas samples were taken at rest and at regular intervals during exercise. Results: Ketone ester consumption increased blood D-?-hydroxybutyrate concentration from 0.2 to 3.7 mM/L (p < 0.01), causing significant falls versus control in blood pH to 7.37 and bicarbonate to 18.5 mM/L before exercise. To compensate for ketoacidosis, minute ventilation was modestly increased (p < 0.05) with non-linearity in the ventilatory response to exercise (ventilatory threshold) occurring at a 22 W lower workload (p < 0.05). Blood pH and bicarbonate concentrations were the same at maximal exercise intensities. There was no difference in exercise performance having consumed the ketone ester or control drink. Conclusion: Athletes compensated for the greater acid load caused by ketone ester ingestion by elevating minute ventilation and earlier hyperventilation during incremental exercise.

SUBMITTER: Dearlove DJ

PROVIDER: S-EPMC6450328 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Nutritional Ketoacidosis During Incremental Exercise in Healthy Athletes.

Dearlove David J DJ Faull Olivia K OK Rolls Edward E Clarke Kieran K Cox Pete J PJ

Frontiers in physiology 20190329

Purpose: Ketosis, achieved through ingestion of ketone esters, may influence endurance exercise capacity by altering substrate metabolism. However, the effects of ketone consumption on acid-base status and subsequent metabolic and respiratory compensations are poorly described. Methods: Twelve athletically trained individuals completed an incremental bicycle ergometer exercise test to exhaustion following the consumption of either a ketone ester [(R)-3-hydroxybutyrate-(R) ...[more]

PMID: 30984015

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Project description:Background:Youth athletes are under increasing pressures to excel in their chosen sport and many turn to nutritional supplements in order to enhance sports performance. However, athletes may obtain their nutritional information via illegitimate sources such as the internet, media, and other athletes, representing miscommunication between sound scientific information and anecdotal experiences. The objective of this investigation was to examine nutrition knowledge of elite youth athletes from a non-residential regional academy of sport. Methods:A previously validated two-part nutrition knowledge questionnaire (NKQ) was administered to 101 (37 male and 64 female) non-residential regional Academy of Sport elite youth athletes at an annual training camp. Part 1 of the NKQ presented demographic questions. Part 2 presented 90 sports nutrition knowledge questions in seven knowledge subcategories (1) Nutrients; (2) Dietary reference intakes (DRI); (3) Fluids/Hydration; (4) Recovery; (5) Weight gain; (6) Weight loss; and (7) Supplements. Results:The mean NKQ score of all athletes was 43.8% (± 11.4). No gender differences observed between nutritional knowledge total scores, however female athletes recorded more 'correct' responses than males (p =?0.02) in the Nutrients subcategory. Majority of athletes had difficulty identifying correct DRI with this subcategory featuring the lowest percentage of 'correct' to 'incorrect' responses (27.1% ±?2.3; p =?0.02). Supplements subcategory displayed much uncertainty with significantly more 'unsure' than 'incorrect' responses (42.4% ±?20.3; p <?0.05). Conclusions:In agreement with previous research, results of the current study indicate that elite youth athletes lack fundamental nutritional knowledge, specifically related to DRI and supplementation. These data provide further support of current recommendations that Academy of Sport youth athletes may benefit from integrated nutrition education conducted by qualified nutrition professionals.

Project description:BACKGROUND:Pleasure is a key factor for physical activity behavior in sedentary individuals. Inhibitory cognitive control may play an important role in pleasure perception while exercising, especially at high intensities. In addition, separate work suggests that autonomic regulation and cerebral hemodynamics influence the affective and cognitive responses during exercise. PURPOSE:We investigated the effects of exercise intensity on affect, inhibitory control, cardiac autonomic function, and prefrontal cortex (PFC) oxygenation. METHODS:Thirty-seven sedentary young adults performed two experimental conditions (exercise and control) in separate sessions in a repeated-measures design. In the exercise condition, participants performed a maximum graded exercise test on a cycle ergometer as we continuously measured oxygen consumption, heart rate variability (HRV), and PFC oxygenation. At each of 8 intensity levels we also measured inhibitory control (Stroop test), associative and dissociative thoughts (ADT), and affective/pleasure ratings. In the control condition, participants sat motionless on a cycle ergometer without active pedaling, and we collected the same measures at the same points in time as the exercise condition. We evaluated the main effects and interactions of exercise condition and intensity level for each measure using two-way repeated measures ANOVAs. Additionally, we evaluated the relationship between affect and inhibitory control, ADT, HRV, and PFC oxygenation using Pearson's correlation coefficients. RESULTS:For exercise intensities below and at the ventilatory threshold (VT), participants reported feeling neutral, with preservation of inhibitory control, while intensities above the VT were associated with displeasure (p<0.001), decreased inhibitory control and HRV (p<0.001), and increased PFC oxygenation (p<0.001). At the highest exercise intensity, pleasure was correlated with the low-frequency index of HRV (r = -0.34; p<0.05) and the low-frequency/high-frequency HRV ratio (r = -0.33; p<0.05). PFC deoxyhemoglobin was correlated with pleasure two stages above the VT (r = -0.37; p<0.05). CONCLUSION:Our results support the notion that exercise at high intensities influences inhibitory control and one's perception of pleasure, which are linked to changes in cardiac autonomic control and cerebral hemodynamics. These findings strengthen the existence of an integrated brain-heart-body system and highlight the importance of exercise intensity in exercise-related behavior in sedentary individuals.

Dataset Information

Nutritional Ketoacidosis During Incremental Exercise in Healthy Athletes.

Publications

Nutritional Ketoacidosis During Incremental Exercise in Healthy Athletes.

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