β-Alanine

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β-Alanine is a nonessential amino acid that is common in many foods that we eat, such as chicken. By itself, β-alanine has limited ergogenic properties. However, in muscle cells, it is the rate-limiting substrate for carnosine synthesis (68). Harris and colleagues (110) reported that four weeks of supplementing with β-alanine (4 to 6 g/day) resulted in a mean increase of 64% in skeletal muscle β-alanine concentrations. In humans, carnosine is found primarily in fast-twitch (Type II) skeletal muscle and is estimated to contribute up to 40% of the skeletal MBC of H+ produced during intense anaerobic exercise, thus encouraging a drop in pH (110, 114). Theoretically, increasing skeletal muscle carnosine levels through chronic training or β-alanine supplementation (or both) would improve MBC and most likely improve anaerobic performance. Interestingly, carnosine concentrations in athletes such as sprinters and bodybuilders appear to be significantly higher than those in marathoners, untrained individuals, and people who are elderly (110, 224).

Suzuki and colleagues (224) examined the relationship between skeletal muscle carnosine levels and high-intensity exercise performance in trained cyclists. The authors reported a significant and positive relationship between carnosine concentration and mean power in a 30-second maximal sprint on a cycle ergometer. This finding supported the theory that skeletal muscle carnosine levels have a positive correlation with anaerobic performance because of the relationship between carnosine and MBC.

Efficacy

β-Alanine has been studied for its effects on strength, aerobic power, and high-intensity short-term exercises interspersed with short recovery intervals. In contrast to creatine, β-alanine does not seem to improve maximal strength (140, 122, 123). Similarly, aerobic power does not appear to be improved with β-alanine supplementation (123, 140). Even though aerobic power is not improved, supporting data indicate that anaerobic threshold is improved with β-alanine supplementation (221, 259). Practically, improving anaerobic threshold (as measured by the lactate and ventilatory thresholds) means that endurance activities can be performed at relatively higher intensities for longer periods. Hill and colleagues (114) examined the effect of β-alanine supplementation on muscle carnosine levels and exercise performance in untrained subjects. In a double-blind fashion, 25 male subjects (19-31 years) supplemented with either 4.0 g β-alanine or sugar placebo for the first week, then with up to 6.4 g for an additional nine weeks. Muscle carnosine levels (via muscle biopsy) and total work done (kilojoules) were measured at weeks 0, 4, and 10 during cycling to exhaustion at maximal power established from a graded exercise cycle ergometry test. Mean carnosine levels increased by 58% at week 4 and an additional 15% at week 10. Additionally, 13% and 16% increases in total work done during cycle ergometry were seen at weeks 4 and 10, respectively.

In a comprehensive review summarizing the effects of β-alanine supplementation on high-intensity performance, Artioli and colleagues (9) stated that β-alanine ingestion is capable of improving performance in exercises resulting in an extreme intramuscular acidotic environment, such as multiple bouts of high-intensity exercises lasting more than 60 seconds, as well as single bouts undertaken when fatigue is already present. High-intensity exercises performed with a lower level of acidosis are unlikely to benefit from β-alanine supplementation.

Adverse Effects

In the published literature, β-alanine ingestion has ranged from 2.4 to 6.4 g per day. In many β-alanine trials, the total daily amount of β-alanine ingestion was divided into two to four smaller doses. The reason for the smaller dosing strategies is to prevent the only reported adverse effect of β-alanine supplementation, which is the symptom of paresthesia (tingling, pricking, or numbness of a person’s skin) (9). Symptoms of paresthesia are triggered by a high and acute single dose and disappear within approximately 1 hour after the ingestion (9, 110).

Developed by the National Strength and Conditioning Association (NSCA), Essentials of Strength Training and Conditioning, Fourth Edition, With Web Resource, is the fundamental preparation text for the Certified Strength and Conditioning Specialist^® (CSCS^®) Exam, as well as a definitive reference that strength and conditioning professionals will consult in everyday practice. The book is available in bookstores everywhere, as well as online at the NSCA Store.