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?-alanine supplementation improves in-vivo fresh and fatigued skeletal muscle relaxation speed.

ABSTRACT: In fresh muscle, supplementation with the rate-limiting precursor of carnosine, ?-alanine (BA), results in a decline in muscle half-relaxation time (HRT) potentially via alterations to calcium (Ca2+) handling. Accumulation of hydrogen cation (H+) has been shown to impact Ca2+ signalling during muscular contraction, carnosine has the potential to serve as a cytoplasmic regulator of Ca2+ and H+ coupling, since it binds to both ions. The present study examined the effect of BA supplementation on intrinsic in-vivo isometric knee extensor force production and muscle contractility in both fresh and fatigued human skeletal muscle assessed during voluntary and electrically evoked (nerve and superficial muscle stimulation) contractions.Twenty-three males completed two experimental sessions, pre- and post- 28 day supplementation with 6.4 g.day-1 of BA (n?=?12) or placebo (PLA; n?=?11). Isometric force was recorded during a series of voluntary and electrically evoked knee extensor contractions.BA supplementation had no effect on voluntary or electrically evoked isometric force production, or twitch electromechanical delay and time-to-peak tension. There was a significant decline in muscle HRT in fresh and fatigued muscle conditions during both resting (3?±?13%; 19?±?26%) and potentiated (1?±?15%; 2?±?20%) twitch contractions.The mechanism for reduced HRT in fresh and fatigued skeletal muscle following BA supplementation is unclear. Due to the importance of muscle relaxation on total energy consumption, especially during short, repeated contractions, BA supplementation may prove to be beneficial in minimising contractile slowing induced by fatigue.The trial is registered with Clinicaltrials.gov, ID number NCT02819505.

SUBMITTER: Jones RL

PROVIDER: S-EPMC5388709 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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β-alanine supplementation improves in-vivo fresh and fatigued skeletal muscle relaxation speed.

Jones Rebecca Louise RL Barnett Cleveland Thomas CT Davidson Joel J Maritza Billy B Fraser William D WD Harris Roger R Sale Craig C

European journal of applied physiology 20170327 5

<h4>Purpose</h4>In fresh muscle, supplementation with the rate-limiting precursor of carnosine, β-alanine (BA), results in a decline in muscle half-relaxation time (HRT) potentially via alterations to calcium (Ca2+) handling. Accumulation of hydrogen cation (H+) has been shown to impact Ca2+ signalling during muscular contraction, carnosine has the potential to serve as a cytoplasmic regulator of Ca2+ and H+ coupling, since it binds to both ...[more]

PMID: 28349262

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Project description:BackgroundType 2 diabetes patients and individuals at risk of developing diabetes are characterized by metabolic inflexibility and disturbed glucose homeostasis. Low carnitine availability may contribute to metabolic inflexibility and impaired glucose tolerance. Here, we investigated whether carnitine supplementation improves metabolic flexibility and insulin sensitivity in impaired glucose tolerant (IGT) volunteers.MethodsEleven IGT- volunteers followed a 36-day placebo- and L-carnitine treatment (2 g/day) in a randomised, placebo-controlled, double blind crossover design. A hyperinsulinemic-euglycemic clamp (40 mU/m2/min), combined with indirect calorimetry (ventilated hood) was performed to determine insulin sensitivity and metabolic flexibility. Furthermore, metabolic flexibility was assessed in response to a high-energy meal. Skeletal muscle acetylcarnitine concentrations were measured in vivo using long echo time proton magnetic resonance spectroscopy (1H-MRS, TE=500 ms) in the resting state (7:00AM and 5:00PM) and after a 30-min cycling exercise. Twelve normal glucose tolerant (NGT) volunteers were included without any intervention as control group.ResultsMetabolic flexibility of IGT-subjects completely restored towards NGT control values upon carnitine supplementation, measured during a hyperinsulinemic-euglycemic clamp and meal test. In muscle, carnitine supplementation enhanced the increase in resting acetylcarnitine concentrations over the day (delta 7:00 AM versus 5:00 PM) in IGT-subjects. Furthermore, carnitine supplementation increased post-exercise acetylcarnitine concentrations and reduced long-chain acylcarnitine species in IGT-subjects, suggesting the stimulation of a more complete fat oxidation in muscle. Whole-body insulin sensitivity was not affected.ConclusionCarnitine supplementation improves acetylcarnitine formation and rescues metabolic flexibility in IGT-subjects. Future research should investigate the potential of carnitine in prevention/treatment of type 2 diabetes.

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?-alanine supplementation improves in-vivo fresh and fatigued skeletal muscle relaxation speed.

Publications

β-alanine supplementation improves in-vivo fresh and fatigued skeletal muscle relaxation speed.

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