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Exogenous ketosis impacts neither performance nor muscle glycogen breakdown in prolonged endurance exercise.

ABSTRACT: Available evidence indicates that ketone bodies inhibit glycolysis in contracting muscles. Therefore, we investigated whether acute exogenous ketosis by oral ketone ester (KE) intake early in a simulated cycling race can induce transient glycogen sparing by glycolytic inhibition, thereby increasing glycogen availability in the final phase of the event. In a randomized crossover design, 12 highly trained male cyclists completed a simulated cycling race (RACE), which consisted of 3-h intermittent cycling (IMT180'), a 15-min time trial (TT15'), and a maximal sprint (SPRINT). During RACE, subjects received 60 g carbohydrates/h combined with three boluses (25, 20, and 20 g) (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KE) or a control drink (CON) at 60 and 20 min before and at 30 min during RACE. KE intake transiently increased blood d-?-hydroxybutyrate to ~3 mM (range: 2.6-5.2 mM) during the first half of RACE (P < 0.001 vs. CON). Blood pH concomitantly decreased from approximately 7.42 to 7.36 (range: 7.29-7.40), whereas bicarbonate dropped from 26.0 to 21.6 mM (range: 20.1-23.7; both P < 0.001 vs. CON). Net muscle glycogen breakdown during IMT180' [KE: -78?±?30 (SD); CON: -60?±?22 mmol/kg wet wt; P = 0.08] and TT15' (KE: -9?±?18; CON: -18?±?18 mmol/kg wet wt; P = 0.35) was similar between KE and CON. Accordingly, mean power output during TT15' (KE: 273?±?38; CON: 272?±?37 W; P = 0.83) and time-to-exhaustion in the SPRINT (KE: 59?±?16; CON: 58?±?17 s; P = 0.66) were similar between conditions. In conclusion, KE intake during a simulated cycling race does not cause glycogen sparing, nor does it affect all-out performance in the final stage of a simulated race.NEW & NOTEWORTHY Exogenous ketosis produced by oral ketone ester ingestion during the early phase of prolonged endurance exercise and against the background of adequate carbohydrate intake neither causes muscle glycogen sparing nor improves performance in the final stage of the event. However, such exogenous ketosis may decrease buffering capacity in the approach of the final episode of the event. Furthermore, ketone ester intake during exercise may reduce appetite immediately after exercise.

SUBMITTER: Poffe C

PROVIDER: S-EPMC7311686 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Exogenous ketosis impacts neither performance nor muscle glycogen breakdown in prolonged endurance exercise.

Poffé Chiel C Ramaekers Monique M Bogaerts Stijn S Hespel Peter P

Journal of applied physiology (Bethesda, Md. : 1985) 20200514 6

Available evidence indicates that ketone bodies inhibit glycolysis in contracting muscles. Therefore, we investigated whether acute exogenous ketosis by oral ketone ester (KE) intake early in a simulated cycling race can induce transient glycogen sparing by glycolytic inhibition, thereby increasing glycogen availability in the final phase of the event. In a randomized crossover design, 12 highly trained male cyclists completed a simulated cycling race (RACE), which consisted of 3-h intermittent ...[more]

PMID: 32407242

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Project description:Key pointsBrief (5-6 days) adaptation to a low carbohydrate high fat diet in elite athletes increased exercise fat oxidation to rates previously observed with medium (3-4 weeks) or chronic (>12 months) adherence to this diet, with metabolic changes being washed out in a similar time frame. Increased fat utilisation during exercise was associated with a 5-8% increase in oxygen cost at speeds related to Olympic Programme races. Acute restoration of endogenous carbohydrate (CHO) availability (24 h high CHO diet, pre-race CHO) only partially restored substrate utilisation during a race warm-up. Fat oxidation continued to be elevated above baseline values although it was lower than achieved by 5-6 days' keto adaptation; CHO oxidation only reached 61% and 78% of values previously seen at exercise intensities related to race events. Acute restoration of CHO availability failed to overturn the impairment of high-intensity endurance performance previously associated with low carbohydrate high fat adaptation, potentially due to the blunted capacity for CHO oxidation.AbstractWe investigated substrate utilisation during exercise after brief (5-6 days) adaptation to a ketogenic low-carbohydrate (CHO), high-fat (LCHF) diet and similar washout period. Thirteen world-class male race walkers completed economy testing, 25 km training and a 10,000 m race (Baseline), with high CHO availability (HCHO), repeating this (Adaptation) after 5-6 days' LCHF (n = 7; CHO: <50 g day-1 , protein: 2.2 g kg-1 day-1 ; 80% fat) or HCHO (n = 6; CHO: 9.7 g kg-1 day-1 ; protein: 2.2 g kg-1 day-1 ) diet. An Adaptation race was undertaken after 24 h HCHO and pre-race CHO (2 g kg-1 ) diet, identical to the Baseline race. Substantial (>200%) increases in exercise fat oxidation occurred in the LCHF Adaptation economy and 25 km tests, reaching mean rates of ∼1.43 g min-1 . However, relative V̇O2 (ml min-1 kg-1 ) was higher (P < 0.0001), by ∼8% and 5% at speeds related to 50 km and 20 km events. During Adaptation race warm-up in the LCHF group, rates of fat and CHO oxidation at these speeds were decreased and increased, respectively (P < 0.001), compared with the previous day, but were not restored to Baseline values. Performance changes differed between groups (P = 0.009), with all HCHO athletes improving in the Adaptation race (5.7 (5.6)%), while 6/7 LCHF athletes were slower (2.2 (3.4)%). Substrate utilisation returned to Baseline values after 5-6 days of HCHO diet. In summary, robust changes in exercise substrate use occurred in 5-6 days of extreme changes in CHO intake. However, adaptation to a LCHF diet plus acute restoration of endogenous CHO availability failed to restore high-intensity endurance performance, with CHO oxidation rates remaining blunted.

Dataset Information

Exogenous ketosis impacts neither performance nor muscle glycogen breakdown in prolonged endurance exercise.

Publications

Exogenous ketosis impacts neither performance nor muscle glycogen breakdown in prolonged endurance exercise.

Similar Datasets

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