title: β-alanine supplementation improves in-vivo fresh and fatigued skeletal muscle relaxation speed.
abstract: OBJECTIVE
  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 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.
  
  
  METHODS
  Twenty-three males completed two experimental sessions, pre- and post- 28 day supplementation with 6.4 g.day-1of BA (n = 12) or placebo (PLA; n = 11). Isometric force was recorded during a series of voluntary and electrically evoked knee extensor contractions.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  The trial is registered with Clinicaltrials.gov, ID number NCT02819505.
authors.affiliation: Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Erasmus Darwin Building, Clifton Lane, Clifton, Nottingham, NG11 8NS, UK.
authors.forename: Rebecca Louise
authors.initials: RL
authors.lastname: Jones
authors.affiliation: Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Erasmus Darwin Building, Clifton Lane, Clifton, Nottingham, NG11 8NS, UK.
authors.forename: Cleveland Thomas
authors.initials: CT
authors.lastname: Barnett
authors.affiliation: Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Erasmus Darwin Building, Clifton Lane, Clifton, Nottingham, NG11 8NS, UK.
authors.forename: Joel
authors.initials: J
authors.lastname: Davidson
authors.affiliation: Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Erasmus Darwin Building, Clifton Lane, Clifton, Nottingham, NG11 8NS, UK.
authors.forename: Billy
authors.initials: B
authors.lastname: Maritza
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK.|Norfolk and Norwich University Hospital, Norwich, Norfolk, UK.
authors.forename: William D
authors.initials: WD
authors.lastname: Fraser
authors.affiliation: Junipa Ltd, Newmarket, Suffolk, UK.
authors.forename: Roger
authors.initials: R
authors.lastname: Harris
authors.affiliation: Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Erasmus Darwin Building, Clifton Lane, Clifton, Nottingham, NG11 8NS, UK. Craig.Sale@ntu.ac.uk.
authors.forename: Craig
authors.initials: C
authors.lastname: Sale
mesh_terms: D006801:Humans; D007537:Isometric Contraction; D008297:Male; D018763:Muscle Fatigue; D009126:Muscle Relaxation / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D055815:Young Adult; D015091:beta-Alanine / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*
chemical_list: D015091:beta-Alanine
keywords: Carnosine; Contractile properties; Electrical stimulation; Muscle fatigue