beta-Alanine Supplementation Augments Muscle Carnosine Content and Attenuates Fatigue During Repeated Isokinetic Contraction Bouts in Trained Sprinters

J Appl Physiol (1985). 2007 Nov;103(5):1736-43. doi: 10.1152/japplphysiol.00397.2007. Epub 2007 Aug 9.

Abstract

Carnosine (beta-alanyl-l-histidine) is present in high concentrations in human skeletal muscle. The ingestion of beta-alanine, the rate-limiting precursor of carnosine, has been shown to elevate the muscle carnosine content. We aimed to investigate, using proton magnetic resonance spectroscopy (proton MRS), whether oral supplementation with beta-alanine during 4 wk would elevate the calf muscle carnosine content and affect exercise performance in 400-m sprint-trained competitive athletes. Fifteen male athletes participated in a placebo-controlled, double-blind study and were supplemented orally for 4 wk with either 4.8 g/day beta-alanine or placebo. Muscle carnosine concentration was quantified in soleus and gastrocnemius by proton MRS. Performance was evaluated by isokinetic testing during five bouts of 30 maximal voluntary knee extensions, by endurance during isometric contraction at 45% maximal voluntary contraction, and by the indoor 400-m running time. beta-Alanine supplementation significantly increased the carnosine content in both the soleus (+47%) and gastrocnemius (+37%). In placebo, carnosine remained stable in soleus, while a small and significant increase of +16% occurred in gastrocnemius. Dynamic knee extension torque during the fourth and fifth bout was significantly improved with beta-alanine but not with placebo. Isometric endurance and 400-m race time were not affected by treatment. In conclusion, 1) proton MRS can be used to noninvasively quantify human muscle carnosine content; 2) muscle carnosine is increased by oral beta-alanine supplementation in sprint-trained athletes; 3) carnosine loading slightly but significantly attenuated fatigue in repeated bouts of exhaustive dynamic contractions; and 4) the increase in muscle carnosine did not improve isometric endurance or 400-m race time.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Administration, Oral
  • Belgium
  • Carnosine / metabolism*
  • Dietary Supplements*
  • Double-Blind Method
  • Exercise / physiology*
  • Humans
  • Isometric Contraction / drug effects
  • Magnetic Resonance Spectroscopy
  • Male
  • Muscle Contraction / drug effects*
  • Muscle Fatigue / drug effects*
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / metabolism
  • Physical Endurance / drug effects*
  • Running
  • Task Performance and Analysis
  • Time Factors
  • beta-Alanine / administration & dosage
  • beta-Alanine / pharmacology*

Substances

  • beta-Alanine
  • Carnosine