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Fighting Muscle Fatigue: How Does it Work?

By USA Hockey, 12/15/17, 6:30AM MST


Almost everyone is familiar with the term “lactic acid build-up.”

Minimizing the negative effects of expending energy in the muscles is not a new concept.  Almost everyone is familiar with the term “lactic acid build-up.”

It is this increase in acidity in the muscles that is the primary contributor to fatigue both during and after exercise and training. However, the focus is now shifting from the concept of minimizing lactic acid build-up to a more accurate model that instead focuses on how acid build-up in the muscles can best be buffered.

And the presence of beta-alanine is quickly emerging as a primary factor in promoting the ability of muscle to buffer the acid-producing hydrogen (H+) ions that are generated during rapid and intense energy production and use.


It is the process of converting glucose to energy in the muscle that produces lactic acid. This lactic acid then breaks down into lactate and hydrogen. It is this increase in hydrogen ions in the muscle that increases muscular acidity, which is the primary contributor to fatigue and soreness.

In muscle, the peptide carnosine serves as a “hydrogen scavenger.” Acting as a “hydrogen scavenger” carnosine will mitigate the adverse impact of muscular acidity, which, in turn, will increase muscle capacity and time-to-failure.

Carnosine is composed of two amino acids:  beta-alanine and histidine, with beta-alanine being the rate-limiting factor in carnosine’s production.

Supplementation of six grams of sustained-release beta-alanine has been shown to increase the amount of carnosine in muscle by as much as 64% after four weeks and as much as 80% after 10 weeks.


Unfortunately, simply taking carnosine is not effective in humans, because carnosine is metabolized before it can ever reach the muscle. 

To counteract this, carnosine’s building blocks – histidine and beta-alanine – must be increased in the muscle to sufficiently increase the level of carnosine.  Carnosine levels in muscles vary from person to person, with higher levels typically occurring in males and in individuals who have more fast-twitch muscles.

Carnosine levels tend to decline with age, but they also can be low from diets that are consistently low in carnosine-containing foods. Carnosine is very abundant in protein-rich foods, such as milks, eggs, and cheese, with the best food sources of carnosine being beef, poultry, and pork products.

This makes beta-alanine supplementation a very reasonable consideration for aging populations and vegetarian/vegan populations.  Beta-alanine supplementation has been shown to increase carnosine levels in both high- and low-baseline level populations.

In addition to its emerging role in buffering muscular acidity, carnosine has also been shown to have significant antioxidant properties.  Carnosine can also play a positive role in chelating heavy metals, which in turn, reduces the production of harmful free radicals.


Anaerobic Performance

Beta-alanine supplementation improved exercise capacity in activities lasting between one and four minutes.


Anaerobic – Beta-alanine showed improvements in the time-to-perceived exhaustion in male and female cyclists and runners during exercise longer than 1 minute but less than 4.5 minutes.

Aerobic – For exercises lasting longer than four minutes, beta-alanine improved time-to-perceived exhaustion compared to placebo.

Studies in 2,000 meter rowing time trials showed a 2-4 second improvement in trial time with beta-alanine supplementation.

Work Capacity

Measuring power output at the neuromuscular fatigue threshold indicates the work capacity of the muscles. Beta-alanine supplementation resulted in a 14-17% increase in physical working capacity in males and females versus placebo.


Carnosine acts as an antioxidant by limiting the accumulation of free radicals from fat oxidation and metal chelation. Further research is dictated to examine the antioxidant properties of beta-alanine.

Aging Populations

Three-month supplementation of beta-alanine increased muscle carnosine in an aging population (ages 55-92 years), resulting in a 29% increase in physical work capacity.


To maximize the impact of beta-alanine supplementation, an extended loading period is recommended. A 2-week loading period resulted in a 20-30% increase in muscle carnosine.

A 4-6 week loading period led to a 40-60% increase in muscle carnosine. Supplementing with beta-alanine when eating during the loading phase has been shown to enhance muscle carnosine concentrations.

The current literature supports a split daily dose of up to six grams of sustained-release beta-alanine, because larger single doses (greater than 800 mg of non-sustained-release beta-alanine) can cause a physical phenomenon known as paraesthesia, or tingling.

In addition, large doses of beta-alanine that are not time-released lead to higher excretion rates, which negatively impacts muscle-loading capacity.

Beta Alanine-SR

  • Provides antioxidant support
  • Increases carnosine levels in muscles
  • Supports the buffering capacity of muscles
  • Helps maintain and promote muscle endurance and power output
  • Helps improve time-to-failure during aerobic and anaerobic exercise
  • PureTab™ sustained-release delivery maximizes benefits while minimizing potential tingling

To learn more about Thorne Nutritional products and our partnership please click here.

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