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 -β-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.

Bicarbonate Unlocks the Ergogenic Action of Ketone Monoester Intake in Endurance Exercise

“…Nonetheless, the effects of acute exogenous ketosis in endurance exercise performance remain a matter of considerable debate. In contrast to the original findings by Cox et al ( 1 ), follow-up studies failed to demonstrate an ergogenic effect of exogenous ketosis on shuttle run time to exhaustion ( 3 ), repeated sprint performance ( 3 , 4 ), 5- and 10-km running performance ( 5 , 6 ), 4–60 min cycling time-trial performance ( 7 – 10 ), and during an incremental cycle test ( 11 ). We recently also found that KE intake during the initial phase of a 3-h 15-min simulated cycling race did not enhance the 15-min time-trial performance, nor sprint performance in the final part of the event ( 12 ).…”

Ketogenic Diets and Exercise Performance

“…As LC/KDs require high fat consumption and present difficulty with long-term adherence, alternative methods for targeting ketosis as a potential intervention for weight loss or as an ergogenic aid are required. In support of these, several studies examined the benefits of ketone body supplements on exercise performance [2,88,89,90,91,92]. Ketone body supplements are commercially available and commonly present in the form of ketone salts (KS) or ketone esters (KE).…”

“…This particular KE, when taken in combination with CHO, results in a 2% increase in exercise performance in trained cyclists [2]. However, not all KE supplements increase exercise performance [90,91,92], calling into question whether the precise formulation of the KE is essential or whether an additional substrate like CHO is required. Of note, the available studies focused on exercise performance in trained endurance athletes, so whether supplementation in recreational athletes or fitness enthusiasts is appropriate is not known.…”

Investigating Ketone Bodies as Immunometabolic Countermeasures against Respiratory Viral Infections

“…Acute cardiovascular changes, such as increasing resting heart rate 162,163 and increasing blood flow to the brain and heart via vasodilation, 162,163,236 are perceived as potentially therapeutic but would need to be monitored in severely ill patient groups. Studies have demonstrated a transient, mild metabolic acidosis following ketone ester administration, a mildly alkalizing effect of ketone salts, 57,237 and a transient fall in plasma potassium with both esters and salts. 57,162 Exogenous ketosis in healthy individuals decreases endogenous ketone production via inhibition of lipolysis and therefore should reduce the risk of uncontrolled ketoacidosis.…”