Deep Dive: Does beta-alanine improve training performance?

Nutritional supplements are a broad category that includes nutritional complements, such as protein powder, and non-nutritional ergogenic aids, like caffeine. One of the most common goals for using them, particularly in competitive sports, is to enhance performance. There are many supplements that, at least in theory, can increase performance through different mechanisms. One such a mechanism involves the delaying and reduction of muscle fatigue, which interferes with muscle function at higher exercise intensities. In part, muscle fatigue results^[1] from the accumulation of metabolites like hydrogen (H⁺) ions, that reduce the muscle pH and affect muscular function.

Carnosine is a di-peptide formed by two amino acids: histidine and beta-alanine (BA). In muscle, carnosine acts as an intracellular buffer, counteracting the increase in H⁺ during exercise. However, dietary carnosine has a very low bioavailability in muscle tissue due to the presence^[2] of carnosinase, a carnosine degrading enzyme, in plasma. Due to this relationship, dietary BA supplementation has become the method of choice for increasing muscle carnosine levels. This increase occurs^[3] with repeated consumption over time in order to accumulate carnosine in muscle, which lacks carnosinase.

Previous data^[4] suggests a small benefit of BA supplementation on exercise capacity and performance. However, the effect of BA specifically in the aerobic-anaerobic transition zone (60–100% VO_2max) has not been meta-analyzed. Examples of activities that exist in this zone include rowing, cycling, and running.

Dietary supplements that increase performance can be very valuable for athletes. One of the main ways in which these supplements could work is by reducing muscle fatigue, which occurs, in part, due to the accumulation of metabolites, such as hydrogen H⁺ ions. This leads to a decrease in the cell’s pH and reduced function. One of the main pH buffers in muscle is carnosine, which is composed of histidine and beta-alanine (BA). Supplementing BA has been shown to increase carnosine levels in muscle and thus potentially counteract muscle fatigue during exercise. However, whether it has any effect specifically during the aerobic-anaerobic transition zone has not been determined.