Exogenous Ketone Salt Supplementation and Whole-Body Cooling Do Not Improve Short-Term Physical Performance

Abstract

Exogenous ketone supplementation and whole-body cooling (WBC) have shown to independently influence exercise metabolism. Whether readily available ketone salts, with and without WBC, would provide similar metabolic benefits during steady-state aerobic and time-trial performances was investigated. Nine active males (VO2peak: 56.3 ± 2.2 mL·kg−1·min−1) completed three single-blind exercise sessions preceded by: (1) ingestion of placebo (CON), (2) ketone supplementation (0.3 g·kg−1 β-OHB) (KET), and (3) ketone supplementation with WBC (KETCO). Participants cycled in steady-state (SS, 60% Wmax) condition for 30-min, immediately followed by a 15-min time trial (TT). Skin and core temperature, cardio-metabolic, and respiratory measures were collected continuously, whereas venous blood samples were collected before and after supplementation, after SS and TT. Venous β-OHB was elevated, while blood glucose was lower, with supplementation vs. CON (p < 0.05). TT power output was not different between conditions (p = 0.112, CON: 190 ± 43.5 W, KET: 185 ± 40.4 W, KETCO: 211 ± 50.7 W). RER was higher during KETCO (0.97 ± 0.09) compared to both CON (0.88 ± 0.04, p = 0.012) and KET (0.88 ± 0.05, p = 0.014). Ketone salt supplementation and WBC prior to short-term exercise sufficiently increase blood β-OHB concentrations, but do not benefit metabolic shifts in fuel utilization or improve time trial performance.

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

“…Upon completion of the pre-load, participants performed a 4-min maximal cycling [51]. More recently, 0.3 g.kg −1 of KS (~ 23 g R,S-βHB) was ingested 30 min prior to commencing a 30-min pre-load at 60% W max followed by a 15-min cycling TT [73]. Whole blood [R-βHB] was increased to ~ 0.9 mM 30 min after ingestion but had declined to ~ 0.5 mM prior to the start of the TT, and average power output during the TT was not different between conditions (KS: 185 ± 40 W; PLA: 190 ± 43 W) [73].…”

“…kg −1 .min −1 12 keto-adapted * (KA) individuals (9 male, 3 female) * At least 3 months consuming ketogenic diet validated by food diary (CHO < 50 g/d), RER < 0.075, and fasting [R-βHB] > 0.5 mM , 40.0 ± 10.5 mL. kg −1 .min −1 Incremental cycling time to exhaustion immediately followed by 30-s Wingate test KS + CAF + AA: 7.2 g R,S-βHB, 100 mg caffeine, 2.7 g taurine, 2.1 leucine CON: Non-caloric water control Single (− 15 min pre-exercise) Double blinded: No Placebo: No Blinding success: No blinding Randomised: Yes Crossover: Yes Dietary control: 24-h food diary and repeat Pre-trial meal: Fasted Fuel during: None Validated exercise test: No Sensitivity of exercise test: CV of 1.2% (own data) Familiarisation trial: No βHB measurement: POC and direct/laboratory assay Time to exhaustion (s) KS + CAF + AA KN: 1246 ± 265* KA: 1159 ± 417* CON KN: 1156 ± 260 KA: 1068 ± 404 ES: KN: 0.34 (small) KA: 0.22 (small) Average power output (W) KS + CAF + AA KN: 432 ± 45 KA: 397 ± 24 CON KN: 414 ± 42 KA: 394 ± 40 ES: KN: 0.41 (small) KA: 0.10 (trivial) Clark et al (2021) [ 73 ] a KS (KetoForce; KetoSports) Racemic 9 healthy active males , 56.3 ± 2.2 mL.kg −1 .min −1 30-min cycling (60% W max ) 15-min cycling TT KS: 0.3 g.kg −1 R,S-βHB PLA: Taste-, colour- and electrolyte-matched non-caloric control Single (− 30 min pre-exercise) Double blinded: Unclear Placebo: Not isocaloric Blinding success: 0%; gastrointestinal symptoms Randomised: Unclear; counterbalanced Crossover: Yes Dietary control: 24-h food diary and repeat Pre-trial meal: Fasted Fuel during: None Validated exercise test: No Sensitivity of exercise test: Not stated Familiarisation trial: No βHB measurement: POC Average power output in TT (W): KS: 185 ± 40.4 PLA: 190 ± 43.5 ES: 0.11 (trivial) Quinones & Lemon (2022) [ 85 ] KS + CAF + AA (KETO//OS-NAT CHARGED; Pruvit) Non-racemic b KS + AA (KETO//OS-NAT; Pruvit) Non-racemic b 13 healthy, young, recreationally active men Exercise ≥ 2 times per week 20-km cycling TT...…”

“…There are eight studies to date on the effects of acute ingestion of KS on exercise performance [ 21 , 45 , 46 , 51 , 73 , 83 – 85 ] (Table 2 ). The earliest of those studies observed impaired performance after ingestion of 0.3 g.kg −1 of KS (~ 25 g R,S-βHB) 50 min prior to exercise, which increased whole blood [R-βHB] to ~ 0.8 mM, but resulted in lower average power output by 7% (− 16 W) and increased time to completion (KS: 711 ± 137 s; placebo [PLA]: 665 ± 120 s) for a 150-kJ cycling TT (~ 10 km) [ 45 ].…”

“…The earliest of those studies observed impaired performance after ingestion of 0.3 g.kg −1 of KS (~ 25 g R,S-βHB) 50 min prior to exercise, which increased whole blood [R-βHB] to ~ 0.8 mM, but resulted in lower average power output by 7% (− 16 W) and increased time to completion (KS: 711 ± 137 s; placebo [PLA]: 665 ± 120 s) for a 150-kJ cycling TT (~ 10 km) [ 45 ]. Several studies since then have observed no effect on exercise performance [ 46 , 51 , 73 , 84 ]. The first of these studies provided two servings of KS providing 11.7 g of R,S-βHB each, the first being at 30 min prior to exercise and the second being 45 min into a 90-min pre-load at 80% VT 2 [ 46 ].…”

“…In the time since 2016 when the first peer-reviewed article detailing the effects of acute ingestion of EKS in humans on exercise metabolism and endurance performance was published [ 44 ], there has been a dramatic increase in the number of articles investigating the effects in humans of acute ingestion of EKS of various types on exercise metabolism, physical and cognitive performance, and recovery from exercise [ 21 , 35 – 38 , 42 , 44 – 49 , 51 , 52 , 54 , 56 – 62 , 64 , 66 – 73 , 78 , 81 , 82 , 84 – 86 ], and in other studies investigating short-term (~ 10 d to 6 weeks) daily consumption [ 74 , 83 , 87 , 99 , 107 – 110 ]. Therefore, this review provides an update on investigations into the effects of EKS on exercise performance and recovery outcomes relevant to athletic performance, as well as discussion of methodological considerations and future directions in this field.…”