Effect of acute ingestion of β‐hydroxybutyrate salts on the response to graded exercise in trained cyclists

Abstract

Acute ingestion of ketone salts induces nutritional ketosis by elevating β-hydroxybutyrate (βHB), but few studies have examined the metabolic effects of ingestion prior to exercise. Nineteen trained cyclists (12 male, 7 female) undertook graded exercise (8 min each at ∼30%, 40%, 50%, 60%, 70%, and 80% VO) on a cycle ergometer on two occasions separated by either 7 or 14 days. Trials included ingestion of boluses of either (i) plain water (3.8 mL kg body mass) (CON) or (ii) βHB salts (0.38 g kg body mass) in plain water (3.8 mL kg body mass) (KET), at both 60 min and 15 min prior to exercise. During KET, plasma [βHB] increased to 0.33 ± 0.16 mM prior to exercise and 0.44 ± 0.15 mM at the end of exercise (both p < .05). Plasma glucose was 0.44 ± 0.27 mM lower (p < .01) 30 min after ingestion of KET and remained ∼0.2 mM lower throughout exercise compared to CON (p < .001). Respiratory exchange ratio (RER) was higher during KET compared to CON (p < .001) and 0.03-0.04 higher from 30%VO to 60%VO (all p < .05). No differences in plasma lactate, rate of perceived exertion, or gross or delta efficiency were observed between trials. Gastrointestinal symptoms were reported in 13 out of 19 participants during KET. Acute ingestion of βHB salts induces nutritional ketosis and alters the metabolic response to exercise in trained cyclists. Elevated RER during KET may be indicative of increased ketone body oxidation during exercise, but at the plasma βHB concentrations achieved, ingestion of βHB salts does not affect lactate appearance, perceived exertion, or muscular efficiency.

Dose Response of a Novel Exogenous Ketone Supplement on Physiological, Perceptual and Performance Parameters

“…We found that neither administration nor dose of βHB+MCT in uenced heart rate, RR, RER, VO 2 , VCO 2 , VE, or estimated metabolic oxidation rates. HR has elevated with ketone salts administration [15,16] or reductions in HR with ester administration [18,20], with the vast majority consistent with our ndings across exogenous ketone supplements [19,[21][22][23]25]. While most exogenous ketone evaluations have not observed changes in RER in agreement with our observations, some analyses have observed differences [8,13,14].…”

“…Ketone salts and/or βHB+MCT have not shown an ability to attenuate exercise lactate productions, consistent with the present ndings [13][14][15][16]25]. However, attenuated lactate production is more consistently observed with ester administration [8,18,20], although it does not always reach signi cance [21,22].…”

“…*** Figure 4 Goes here*** Discussion A consistent nding across all exogenous ketone bodies is their ability to induce rapid and widespread changes in metabolism, including consistent changes in circulating metabolic concentrations, ketones, glucose, lactate, amino acids, and/or free-fatty acids. Unsurprisingly, all analyses to date have demonstrated that exogenous ketones signi cantly elevate circulating blood ketones, although to differing extents pending the exogenous agent [5,8,[13][14][15][16][17][18][19][20][21][22][23]. Synthetic 1,3 BD and/or esters raise R-βHB to a greater extent than ketone salts [3,6].…”

“…The physiologic, perceptual, and/or performance impact of exogenous ketone bodies' have been mostly con ned to the administration of individual types [5,8,[13][14][15][16][17][18][19][20][21][22][23]. However, Kesl et al and Ari et al illustrated unique metabolic kinetics when co-administering diverse forms of exogenous ketones [3,24].…”

“…Consequently, our group explored the metabolic and performance impact of βHB-salts and MCTs on 5-km running in well trained runners and found that this was well tolerated, altered systemic metabolism, and augmented and attenuated 8/10 and 2/10 5k runner performance, respectively [25]. However, furthering limiting our knowledge on the impact of exogenous ketones bodies, is that almost all human trials has explored single dose/dosing protocols [5,8,[13][14][15][16][17][18][19][20][21][22][23] limiting our understanding on the potential convergent and/or divergent dose-response across physiologic, metabolic, and performance parameters, with limited exception [6,8]. Thus, we explored both the administration and dose response of βHB-salt and MCT on physiological, perceptual, as well as physical and cognitive performance parameters.…”