By: Jeffrey R. Stout, Ph.D., CSCS, FISSN, FNSCA
Date Published: May 2011

Summary: Beta-alanine supplementation (3.2g to 6.4g per day) may elevate skeletal muscle carnosine levels and enhance exercise performance in untrained subjects. Future studies need to examine whether beta-alanine supplementation can increase skeletal muscle carnosine levels and exercise performance in trained athletes as well as determine the combined effect of beta-alanine supplementation and training on performance.

Beta-alanine is a non-essential amino acid that is common in many foods that we eat, such as chicken. Beta-alanine is not much of an ergogenic aid by itself. However, when it enters the muscle cell, it becomes the rate limiting substrate to carnosine synthesis (1). In fact, Harris (2) reported that 4 weeks of supplementing beta-alanine (4 to 6 grams per day) resulted in a mean increase of 64% in skeletal muscle. Supplementing L-carnosine can also increase skeletal muscle carnosine concentrations. Once L-carnosine enters the digestive system, it is hydrolyzed into histidine and beta-alanine, which is then taken up by skeletal muscle and synthesized into carnosine (2). Due to the immediate hydrolysis, carnosine can not be taken up into the muscle intact.

Carnosine, found primarily in fast-twitch skeletal muscle, contributes to buffering of H+ thus attenuating a drop in pH associated with anaerobic metabolism. Interestingly, carnosine concentrations in athletes, such as sprinters, appear to be significantly higher than those of marathoners, untrained individuals, and the elderly (2). Furthermore, intense physical training is capable of increasing muscle carnosine levels. Twelve days of intense training of elite speed skaters has been shown to increase muscle carnosine content by 87% (2).

Suzuki et al. (5) recently examined the relationship between skeletal muscle carnosine levels and high intensity exercise performance. Suzuki et al. (5) reported there was a significant relationship between carnosine concentration and the mean power from a 30 second maximal sprint on a cycle ergometer. Basically, the higher the carnosine, the better the performance. In theory, increasing skeletal muscle carnosine levels (via beta-alanine supplementation or intense training) should increase buffering capacity, delay fatigue, and increase exercise performance.

Recently Hill et al. (3) examined the effect of beta-alanine supplementation on muscle carnosine levels and exercise performance in untrained subjects. In double blind fashion, twenty male subjects (19-31yrs) were supplemented either 4.0g beta-alanine or sugar placebo for the first week, then up to 6.4g for an additional 9 weeks. Muscle carnosine levels (via muscle biopsy) and work done were measured at weeks 0, 4, and 10 during cycling to exhaustion at 110% of estimated power max. Mean carnosine levels increased by 58% at week 4 and an additional 15% at week 10. Further, there was about a 16% increase in total work done during cycle ergometry at weeks 4 and 10.

In another study, Stout et al. (4) examined the effects of beta-alanine supplementation on physical working capacity at fatigue threshold (PWCFT) in untrained young men. In double blind fashion, subjects consumed either 1.6g of beta-alanine or sugar placebo four times per day for six days, then 3.2 grams per day 22 days. Prior to and following supplementation, the subjects performed an incremental cycle ergometry test to determine PWCFT, which was determined from bipolar surface electromyography recorded from the vastus lateralis muscle. The results revealed a significantly greater increase in PWCFT of 9% over placebo. The findings suggest that beta-alanine supplementation for 28 days may delay the onset of neuromuscular fatigue.

In conclusion, beta-alanine supplementation (3.2g to 6.4g per day) appears to elevate muscle carnosine levels and enhance exercise performance in untrained subjects. Future studies need to examine whether beta-alanine supplementation can increase muscle carnosine levels and exercise performance in highly trained athletes. Further, future investigations should also examine the combined effect of beta-alanine supplementation and training on performance.

References

1. Dunnett M., R. C. Harris. Influence of oral beta-alanine and L-histidine supplementation on the carnosine content of the gluteus medius. Equine Vet J. 30(Suppl): 499-504, 1999.
2. Harris R. C. Muscle carnosine elevation with supplementation and training, and the effects of elevation on exercise performance. (Presented at the International Society of Sports Nutrition Annual conference, 2005, New Orleans.).
3. Hill C. A., R. C. Harris, H. J. Kim, L. Boobis, C. Sale, J. A. Wise. Theffect of beta-alanine and creatine monohydrate supplementation on muscle composition and exercise performance. (Presented at the American College of Sports Medicine Annual conference, 2005, Nashville.)
4. Stout J. R., J. O’Kroy, M. Mielke, R. Zoeller, D. Torok, J.T. Cramer, and B. S. Graves. Effects of 28 days of beta-alanine and creatine monohydrate supplementation on physical working capacity at neuromuscular fatigue threshold. (Presented at the International Society of Sports Nutrition Annual conference, 2005, New Orleans.).
5. Suzuki Y., I. Osamu, N. Mukai, H. Takahashi, and K. Takamatsu. High level of skeletal muscle carnosine contributes to the latter half of exercise performance during 30-s maximal cycle ergometer sprinting. Jap. J. Physiol. 52:199-200. 2002.