Dwayne N. Jackson, PhD
We all know that elevated training intensity requires an optimal state of mind, but many fail to consider that superior workouts also rely on having an optimal muscle cellular environment. At the end of the day, the more reps and sets you can complete during training sessions, the greater the stimulus for muscle growth. Currently there are number of supplements on the market that claim to decrease muscular fatigue when you train, but none have received more scientific support than beta-alanine.
Beta-alanine is a non-proteinogenic amino acid, meaning that it is not involved in synthesizing proteins. It is not available in abundance in the foods we eat, but the body synthesizes beta-alanine by hydrolyzing di-peptides (i.e., carnosine, anserine, and balenine) when we eat protein rich foods (like fish, chicken, and beef). The liver is also capable of synthesizing beta-alanine from pyrimidine nucleotides, through uracil and thymine degradation.
Relationship between beta-alanine supplementation and muscle carnosine
In skeletal muscle, beta-alanine and histidine form the di-peptide carnosine—where the level of beta-alanine limits carnosine production. As such, when beta-alanine is available in excess (i.e., supplemented) it leads to elevated muscle carnosine levels. Science has shown that 4 weeks of beta-alanine supplementation can increase muscle carnosine levels by more than 60%.
What do we want elevated muscle carnosine?
The earliest studies investigating the performance enhancing effects of elevated muscle carnosine were motivated by data illustrating that animals with the greatest capacity for prolonged high intensity exercise also had the highest intramuscular carnosine levels. Furthermore, these studies noted that carnosine levels were relatively higher in fast-twitch versus slow twitch muscle fibers. More recently, scientists have concluded that advanced bodybuilders have elevated carnosine levels in quadriceps (vastus lateralus) muscle.
The main mechanism by which elevated muscle carnosine levels increase muscle function and performance is through its ability to buffer skeletal muscle pH (acidity) during prolonged high intensity exercise. Since one of the primary causes of fatigue during heavy exercise is metabolically mediated decreases in pH (or acidosis), then it follows why increased intramuscular carnosine levels would be beneficial to bodybuilders and strength athletes. Beyond its buffering effects, high muscle carnosine also acts as a potent antioxidant and metal chelator. Thus, through its effects on free radical scavenging, scientists hypothesize that high carnosine levels prolong neuromuscular excitation-contraction coupling.
Beta-alanine and performance
Beta-alanine supplementation has been reported to improve anaerobic threshold and increase power output achieved at lactate threshold. In support, research on women supplemented with beta-alanine illustrated that they had an approximately 14% increase in the ventilatory threshold during maximal cycling exercise. As well, in football players undergoing a strength-training program, 30-days of beta-alanine supplementation resulted in greater training volume and lower subjective indices of fatigue compared to those who took a placebo. Such benefits of beta-alanine have been also shown in resistance trained men where 4-weeks of supplementation led to a 22% increase in the number reps completed during workouts.
Beyond increasing training volume, studies have also shown that beta-alanine supplementation can delay neuromuscular fatigue. In fact, 28-days of combined beta-alanine and creatine supplementation was reported to increase the work capacity at fatigue threshold in strength and power athletes. Interestingly, a follow up study conducted by the same research team showed no effect of creatine supplementation alone on decreasing neuromuscular fatigue; thus, illustrating that this ergogenic effect is unique to beta-alanine. These benefits of beta-alanine supplementation on neuromuscular fatigue are likely due the enhanced antioxidant effects from the resulting elevatation in muscle carnosine.
The effect of beta-alanine supplementation on rowing performance has been evaluated in elite level rowers. In this study, rowers took either 5g of beta-alanine or a placebo and carried out a 2000 m rowing ergometer performance test. It was reported that those who took beta-alanine completed the test 4.3 seconds faster than those who took the placebo—which correlated with up to 45% greater calf muscle carnosine content in the supplemented group. In another performance-based study, elite cyclists were given either beta-alanine (2-4g) or a placebo for 8 weeks and tested on cycling sprint performance after a 110-min simulated endurance road race. It was found that average power and peak power (during sprinting) increased by 5 and 11% respectively in the beta-alanine group compared to placebo.
Beta-alanine and increased muscularity
Since beta-alanine supplementation can delay workout fatigue and increase training volume, then it is not surprising that training with beta-alanine supplementation leads to improvements in body composition. In support, it was reported that subjects who completed a high intensity interval-training program combined with beta-alanine supplementation had greater lean mass gain and fat loss compared to those who trained while taking a placebo. Along the same line, research has shown that combining beta-alanine and creatine with resistance training leads to synergistic increases in lean body mass over time.
Beta-alanine dosing schedule
This amino acid is generally safe to take in moderate doses; however high single doses (>800 mg) have been shown to cause tingling/numbness (paresthesia) in hands and skin that disappear within an hour of ingesting. One other concern is that high doses of beta-alanine may create an osmotic gradient that can decrease the body’s taurine levels (taurine is important for the maintenance of healthy heart function). As such, using a moderate (but frequent) dosing schedule will assure that you get all of the performance benefits, with no side effects. Based on this, any single dose of beta-alanine should not exceed 800 mg. Based on pharmacodynamic data, the most effective way to dose beta-alanine without side effects is to take 10 mg/kg/day and split into two doses. It will take about 4 weeks to notice maximum benefits, as muscle carnosine levels are reported to take up to 12 weeks to peak.
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