Effect of Exogenous Acute beta-Hydroxybutyrate Administration on Different Modalities of Exercise Performance in Healthy Rats

Purpose: A ketone body (beta-hydroxybutyrate [beta-HB]) is used as an energy source in the peripheral tissues. However, the effects of acute beta-HB supplementation on different modalities of exercise performance remain unclear. This study aimed to assess the effects of acute beta-HB administration on the exercise performance of rats. Methods: In study 1, Sprague-Dawley rats were randomly divided into six groups: endurance exercise (EE + PL and EE + KE), resistance exercise (RE + PL and RE + KE), and high-intensity intermittent exercise (HIIE + PL and HIIE + KE) with placebo (PL) or beta-HB salt (KE) administration. In study 2, metabolome analysis using capillary electrophoresis mass spectrometry was performed to profile the effects of beta-HB salt administration on HIIE-induced metabolic responses in the skeletal and heart muscles. Results: The maximal carrying capacity (rest for 3 min after each ladder climb, while carrying heavy weights until the rats could not climb) in the RE + KE group was higher than that in the RE + PL group. The maximum number of HIIE sessions (a 20-s swimming session with a 10-s rest between sessions, while bearing a weight equivalent to 16% of body weight) in the HIIE + KE group was higher than that in the HIIE + PL group. However, there was no significant difference in the time to exhaustion at 30 m center dot min(-1) between the EE + PL and the EE + KE groups. Metabolome analysis showed that the overall tricarboxylic acid cycle and creatine phosphate levels in the skeletal muscle were higher in the HIIE + KE group than those in the HIIE + PL group. Conclusions: These results indicate that acute beta-HB salt administration may accelerate HIIE and RE performance, and the changes in metabolic responses in the skeletal muscle after beta-HB salt administration may be involved in the enhancement of HIIE performance.