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β-Alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters

¹Department of Movement and Sport Sciences, and ²Department of Electronics and Information Systems, Medical Image and Signal Processing, Ghent University, Ghent, Belgium; ³School of Sports, Exercise and Health Sciences, University of Chichester, Chichester, United Kingdom; ⁴Department of Radiology, Ghent Institute for Functional Magnetic Resonance Imaging, Ghent University, Ghent, Belgium; and ⁵Natural Alternatives International, San Marcos, California

Submitted 13 April 2007 ; accepted in final form 2 August 2007

Carnosine (β-alanyl-L-histidine) is present in high concentrations in human skeletal muscle. The ingestion of β-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 β-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 β-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. β-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 β-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 β-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.

buffer capacity; ergogenic supplements; nuclear magnetic resonance; exercise performance; track and field

This article has been cited by other articles:

				A. Baguet, H. Reyngoudt, A. Pottier, I. Everaert, S. Callens, E. Achten, and W. Derave Carnosine loading and washout in human skeletal muscles J Appl Physiol, March 1, 2009; 106(3): 837 - 842. [Abstract] [Full Text] [PDF]