BETA-ALANINE SUPPLEMENTS

BETA-ALANINE SUPPLEMENTS

Evidence Shows This Amino Acid Boosts Athletic Performance

The use of dietary supplements among athletes is wide­spread. In some sports, rates as high as 89% have been reported. While this percentage may seem high, prevalence estimates can vary substantially for various reasons: Research­ers classify dietary supplements differently; athletes choose supplements based on the sport they play; and various levels of competition can impact an athlete’s decision to use them. How­ever, most studies indicate that at least 50% of competitive ath­letes are using one or more supplements.

Some athletes take them to maintain good health, prevent illness, and compensate for a poor diet, although most use supplements for their ergogenic benefits or their potential to aid in recovery following exercise.

One particular supplement that’s been shown to enhance performance among athletes is beta-alanine, a naturally occur­ring amino acid in the body that plays a role in delaying muscle fatigue and improving endurance.

Beta-Alanine’s Role

Supplements commonly used by athletes are muscle-buff­ering agents. As exercise intensity increases and the demand for energy outpaces the capacity of aerobic metabolism, the body shifts to rely on anaerobic metabolism (eg, glycolysis) for energy. This results in the production of additional H+ ions (a by-product of metabolism) as lactic acid accumulates in muscle tissue, negatively affecting performance. The body attempts to fight this intramuscular change in pH by buffer­ing hydrogen, a physiologic correction that can delay fatigue.

One buffering agent available to the body is carnosine, a dipeptide naturally found in skeletal muscle. The concentration of intra­muscular carnosine fluctuates depending on need, with higher concentrations in fast-twitch muscle fibers used by bodybuilders, rowers, cyclists, and sprinters during explosive, high-intensity exercise when anaerobic metabo­lism is a primary energy source. In addition to its potential as a buffering agent, carno­sine is believed to have other benefits that can enhance exercise performance. Studies have demonstrated that carnosine helps maintain adequate stores of adenosine triphosphate, affects muscle contractility by increasing muscle fiber sensitivity to calcium, and acts as an antioxidant to combat oxidative stress from exercise.

Beta-alanine is more than likely the rate-limiting substrate in the production of carnosine, meaning that without beta-alanine, carnosine isn’t produced. As such, athletes supplement with beta-alanine in the hopes that muscle carnosine levels will increase, enhancing the body’s capacity to buffer H+ ions gen­erated by intense exercise, thereby prolonging time to fatigue and improving athletic performance.

A Look at the Research

Evidence consistently shows that muscle carnosine levels increase with beta-alanine supplementation. Available research indicates that a loading period of at least two weeks is necessary and that there’s no upper limit on increasing intramuscular concentration. In addition, the majority of studies provide evidence of the ergogenic benefits associated with beta-alanine use in high-intensity and resistance-training exercise. Individuals supplementing with beta-alanine have demonstrated improved time to fatigue on maximal effort cycling tests, greater ability to sustain power output, improved measures of muscle torque, increased ventilatory threshold and time to exhaustion, enhanced physical working capacity, and gains in lean body mass. Whether these benefits translate to improved exercise performance, however, is less clear.

In one study, Derave and colleagues3 failed to find an improved 400-m sprint time for trained athletes given beta-alanine (4.8 g/kg over four weeks), despite seeing evidence of decreased fatigue and increases in muscle torque. Another study by Sweeney and colleagues4 also failed to support improvements in performance (using sprint tests and mea­sures of horizontal power) with beta-alanine use in physically active college males. However, Baguet and collegues5 studied the effects of beta-alanine supplementation (5 g/day for seven weeks) in 18 elite Belgian rowers and demonstrated a positive effect on performance. Rowers in the supplement group were 4.3 seconds faster in a 2,000-m ergometer test than the pla­cebo group. To put this into context, the difference between the gold and bronze medals at the 2008 Summer Olympics in the men’s eight rowing competition was 1.45 seconds.

Reasons for the conflicting results can be attributed to dif­ferences in study design, such as varying supplement dosages, loading procedures, measures of performance, and the ath­letes’ training level. Regardless of the mixed research findings, it’s becoming increasingly clear that ergogenic effects do exist.

What the Future Holds

Research is ongoing in many respects. Determining the exact dosage of beta-alanine most likely to enhance perfor­mance is important. Current recommendations range from 2.4 g to 6.4 g/day, but exactly what amount of the supplement maximizes physiological effects is unknown. Even though side effects of beta-alanine are limited, nutrition professionals need to caution clients since paraethesia (a mild tingling sen­sation) has been reported with doses in excess of 10 mg/kg of body weight and long-term safety is unknown. Because of this side effect, several doses are spaced over the course of a day to reach the recommended daily amount. Moreover, research­ers are continuing to investigate how long athletes should take the supplement, if a loading period is really necessary, and how specific training regimens can augment benefits. Researchers also are trying to determine whether combining beta-alanine with other dietary supplements—creatine in particular—can further enhance ergogenic benefits.

Bottom Line for RDs

Beta-alanine is a supplement to keep an eye on, especially when working with athletes. While RDs traditionally work with clients to help them consume nutrients through food, recent research suggests that athletes who heavily rely on anaero­bic pathways for energy or resistance training may benefit from beta-alanine supplementation. Sports dietitians can help athletes appropriately evaluate whether beta-alanine can be beneficial given the sport they play and their dietary intake, nutritional status, competitive level, and training demands. 

Healt Information Systems   — Christin L. Seher, MS, RD, LD, is a dietitian, instructor, and nutrition consultant in northeast Ohio.

BETA-ALANINE SUPPLEMENTS