Abstract
Purpose: The purpose of this study was to evaluate the effects of a ketone monoester supplement on indices of muscle damage during recovery after eccentric exercise.Methods: In a randomized, double-blind, independent group design, 20 moderately active healthy young adults consumed 360 mg per kg−1 bodyweight of a ketone monoester (KET) or energy-matched carbohydrate (CON) supplement twice daily following eccentric exercise (drop jumps). Maximal isometric voluntary contraction (MIVC) torque, counter-movement jump (CMJ) height, and muscle soreness were measured before (PRE), and immediately (POST), 24 h and 48 h post-exercise. Blood samples were collected for analysis of β-hydroxybutyrate (β-OHB), creatine kinase (CK), and select pro- and anti-inflammatory cytokines.Results: Peak blood β-OHB concentration after supplement intake was greater (P < 0.001) in KET (4.4 ± 0.8 mM) vs. CON (0.4 ± 0.3 mM). Exercise increased CK concentration at 24 h and 48 h vs. PRE (time: P < 0.001) with no difference between KET and CON. Exercise reduced MIVC (KET: −19.9 ± 14.6; CON: −22.6 ± 11.1%) and CMJ (KET: −11.0 ± 7.5; CON: −13.0 ± 8.7%) at POST relative PRE; however, there was no difference between KET and CON on the recovery of MIVC at 24 h (KET: −15.4 ± 20.4; CON: −18.7 ± 20.1%) or 48 h (KET: −7.2 ± 21.2; CON: −11.8 ± 20.2%), or CMJ at 24 h (KET: −9.2 ± 11.5; CON: −13.4 ± 10.8) or 48 h (KET: −12.5 ± 12.4; CON: −9.1 ± 11.7). Muscle soreness was increased during post-exercise recovery (time: P < 0.001) with no differences between KET and CON. Monocyte chemoattractant protein-1 was greater (group: P = 0.007) in CON (236 ± 11 pg/mL) vs. KET (187 ± 11 pg/mL).Conclusion: In conclusion, twice daily ingestion of a ketone monoester supplement that acutely elevates blood β-OHB concentration does not enhance the recovery of muscle performance or reduce muscle soreness following eccentric exercise in moderately active, healthy young adults.
Highlights
Exercise-induced muscle damage (EIMD) is a non-pathological condition that occurs in response to unaccustomed exercise involving repeated eccentric muscle contractions
The main consequences of EIMD are a temporary reduction in muscle function and increased muscle soreness accompanied by an increase in intramuscular proteins [e.g., creatine kinase (CK)] in the blood and swelling of the involved muscle group [1]
We evaluated the impact of twice daily supplementation (360 mg per kg−1 bodyweight per serving) with a ketone monoester (KET) as compared to an energy-matched carbohydrate control (CON) on indices of EIMD during recovery from a single bout of eccentric exercise in healthy, moderately active, young adults
Summary
Exercise-induced muscle damage (EIMD) is a non-pathological condition that occurs in response to unaccustomed exercise involving repeated eccentric (i.e., lengthening) muscle contractions. EIMD may negatively impact the ability to perform during subsequent training/exercise sessions. The mechanisms of EIMD are complex but are thought to involve both a primary and secondary phase of damage [2, 3]. The primary phase of EIMD involves ultrastructural damage to the muscle and/or impairments in excitation-contraction coupling due to the mechanical work performed during exercise [2, 3]. The secondary phase of EIMD occurs in response to the primary phase and involves biochemical changes, the hallmarks of which are inflammation and oxidative stress, that may further exacerbate damage to the muscle and surrounding tissue [4]. Given the negative symptoms associated with EIMD, there is significant interest among athletes, coaches, and the broader fitness community on novel therapeutic approaches that may effectively reduce indices of EIMD and accelerate recovery after eccentric exercise
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