Exogenous Ketosis Improves Sleep Efficiency and Counteracts the Decline in REM Sleep after Strenuous Exercise

INTRODUCTION

Available evidence indicates that ketone bodies may improve sleep quality. Therefore, we determined whether ketone ester (KE) intake could counteract sleep disruptions induced by strenuous exercise.

METHODS

Ten well-trained cyclists with good sleep quality participated in a randomized crossover design consisting of two experimental sessions each involving a morning endurance training and an evening high-intensity interval training ending 1 h before sleep, after which polysomnography was performed overnight. Postexercise and 30 min before sleeping time, subjects received either 25 g of KE (EX KE ) or a placebo drink (EX CON ). A third session without exercise but with placebo supplements (R CON ) was added to evaluate the effect of exercise per se on sleep.

RESULTS

Blood d -β-hydroxybutyrate concentrations transiently increased to ~3 mM postexercise and during the first part of the night in EX KE but not in EX CON or R CON . Exercise significantly reduced rapid eye movement sleep by 26% ( P = 0.001 vs R CON ) and increased wakefulness after sleep onset by 95% ( P = 0.004 vs R CON ). Interestingly, KE improved sleep efficiency by 3% ( P = 0.040 vs EX CON ) and counteracted the exercise-induced decrease in rapid eye movement sleep ( P = 0.011 vs EX CON ) and the increase in wakefulness after sleep onset ( P = 0.009 vs EX CON ). This was accompanied by a KE-induced increase in dopamine excretion ( P = 0.033 vs EX CON ), which plays a pivotal role in sleep regulation. In addition, exercise increased sleep spindle density by 36% ( P = 0.005 vs R CON ), suggesting an effect on neural plasticity processes during sleep.

CONCLUSIONS

These data indicate that KE ingestion improves sleep efficiency and quality after high-intensity exercise. We provide preliminary evidence that this might result from KE-induced increases in dopamine signaling.

Exogenous Ketosis Impairs 30-min Time-Trial Performance Independent of Bicarbonate Supplementation

PURPOSE

We recently demonstrated that coingestion of NaHCO3 to counteract ketoacidosis resulting from oral ketone ester (KE) intake improves mean power output during a 15-min time trial (TT) at the end of a 3-h cycling race by ~5%. This ergogenic effect occurred at a time when blood ketone levels were low, as ketosis was only induced during the initial ~2 h of the race. Therefore, in the current study, we investigated whether performance also increases if blood ketone levels are increased in the absence of ketoacidosis during high-intensity exercise.

METHODS

In a double-blind crossover design, 14 well-trained male cyclists completed a 30-min TT (TT30') followed by an all-out sprint at 175% of lactate threshold (SPRINT). Subjects were randomized to receive (i) 50 g KE, (ii) 180 mg·kg-1 body weight NaHCO3 (BIC), (iii) KE + BIC, or (iv) a control drink (CON).

RESULTS

KE ingestion increased blood d-ß-hydroxybutyrate to ~3-4 mM during the TT30' and SPRINT (P < 0.001 vs CON). In KE, blood pH and bicarbonate concomitantly dropped, causing 0.05 units lower pH and 2.6 mM lower bicarbonate in KE compared with CON during the TT30' and SPRINT (P < 0.001 vs CON). BIC coingestion resulted in 0.9 mM higher blood d-ß-hydroxybutyrate (P < 0.001 vs KE) and completely counteracted ketoacidosis during exercise (P > 0.05 vs CON). Mean power output during TT30' was similar between CON and BIC at 281 W, but was 1.5% lower in the KE conditions (main effect of KE: P = 0.03). Time to exhaustion in the SPRINT was ~64 s in CON and KE and increased by ~8% in the BIC conditions (main effect of BIC: P < 0.01).

DISCUSSION

Neutralization of acid-base disturbance by BIC coingestion is insufficient to counteract the slightly negative effect of KE intake during high-intensity exercise.

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

PURPOSE

We recently reported that oral ketone ester (KE) intake before and during the initial 30 min of a 3 h 15 min simulated cycling race (RACE) transiently decreased blood pH and bicarbonate without affecting maximal performance in the final quarter of the event. We hypothesized that acid-base disturbances due to KE overrules the ergogenic potential of exogenous ketosis in endurance exercise.

METHODS

Nine well-trained male cyclists participated in a similar RACE consisting of 3 h submaximal intermittent cycling (IMT180') followed by a 15-min time trial (TT15') preceding an all-out sprint at 175% of lactate threshold (SPRINT). In a randomized crossover design, participants received (i) 65 g KE, (ii) 300 mg·kg-1 body weight NaHCO3 (BIC), (iii) KE + BIC, or (iv) a control drink (CON), together with consistent 60 g·h-1 carbohydrate intake.

RESULTS

KE ingestion transiently elevated blood D-ß-hydroxybutyrate to ~2-3 mM during the initial 2 h of RACE (P < 0.001 vs CON). In KE, blood pH concomitantly dropped from 7.43 to 7.36 whereas bicarbonate decreased from 25.5 to 20.5 mM (both P < 0.001 vs CON). Additional BIC resulted in 0.5 to 0.8 mM higher blood D-ß-hydroxybutyrate during the first half of IMT180' (P < 0.05 vs KE) and increased blood bicarbonate to 31.1 ± 1.8 mM and blood pH to 7.51 ± 0.03 by the end of IMT180' (P < 0.001 vs KE). Mean power output during TT15' was similar between KE, BIC, and CON at ~255 W but was 5% higher in KE + BIC (P = 0.02 vs CON). Time to exhaustion in the sprint was similar between all conditions at ~60 s (P = 0.88). Gastrointestinal symptoms were similar between groups.

DISCUSSION

The coingestion of oral bicarbonate and KE enhances high-intensity performance at the end of an endurance exercise event without causing gastrointestinal distress.