Prevent Muscle Fatigue
The Top 4 Lactic Acid Buffers
Many decades ago, the Nobel Prize-winning physiologist A.V. Hill noticed that hydrogen ions or acids accumulate inside muscle cells during strenuous activity.1 Aware that acid accumulation within the muscle cell might impair performance, Hill speculated that muscle cells must possess compounds known as buffers that chemically counteract the negative influence of acid accumulation, facilitating normal muscle function.
Since then, many lines of scientific evidence have expanded on Hill’s original discovery, confirming that anaerobic glycolysis serves as the primary energy-producing pathway2 within the muscle cell during intense exercise— resulting in the rapid accrual of lactic acid, which causes a significant decrease in muscle pH. Moreover, additional research has shown that greater lactic acid amounts within muscle inhibit energy production while simultaneously reducing muscle force production.2,3,4 Altogether, such changes severely compromise exercise capacity and recovery rates, ultimately weakening performance in the weight room and the ability to pack on muscle mass.5
Impressively, A.V. Hill was also prescient regarding the existence of buffering compounds— as the body is loaded with many different buffering systems that protect the muscle from a low pH environment caused by lactic acid buildup.4,6 The most well-described and ergogenic of these buffers include bicarbonate and carnosine. While bicarbonate is the primary buffer outside of the muscle cell where it buffers blood pH, carnosine accounts for the large majority of muscle buffering.7,8 Consequently, the use of both of these naturally occurring buffers should safeguard against low pH levels in muscle tissue as well as the entire body— improving overall performance for a more optimal workout. Here’s the leading four lactic acid buffers:
1) Role of Carnosine as a Muscle Cell Buffer
The dipeptide carnosine, consisting of the amino acids beta-alanine and histidine, functions as a potent intra-muscular buffer by directly binding hydrogen ions— which neutralizes muscle acidity. Carnosine’s muscle-buffering capacity is important for muscle growth as it increases the fatigue threshold, allowing for a greater workload while lifting weights.
Because carnosine is synthesized from beta-alanine and histidine, supplementing your diet with beta-alanine or histidine should, in theory, increase muscle carnosine levels. However, only beta-alanine consumption has clearly been shown to boost intra-muscular carnosine while histidine intake has no effect on carnosine levels. This is because histidine is normally abundant within the muscle cell and at a much higher concentration than beta-alanine. As a result, additional histidine consumption is not needed to synthesize more carnosine— while greater beta-alanine consumption is essential.
As for carnosine’s ability to increase intramuscular carnosine, some studies have shown that large amounts of carnosine do increase muscle carnosine— yet none of these studies have shown a positive influence on exercise performance.9,10
So, taking everything into consideration, only beta-alanine has a positive impact on carnosine formation and muscle function, making it the best choice for improving buffering capacity within muscle tissue.
2) Beta-alanine Boosts Carnosine, Buffers Muscle and Enhances Strength
15FD018-FATIGUE-insBeta-alanine is an amino acid that has numerous positive effects on health and exercise performance. Within muscle cells, as previously mentioned, beta-alanine functions as a building block for carnosine. Several independent studies have clearly illustrated the positive influence of beta-alanine consumption on carnosine production in muscle. In these studies, a significant increase in muscle carnosine of approximately 50 percent was measured when using three to six grams of beta-alanine per day over a four- to eight-week time frame.11,12
In addition to beta-alanine supporting carnosine synthesis, it has also been shown to reduce muscle acidosis. In one study by Baguet et al.13, subjects consuming 4.8 grams of beta-alanine per day for four weeks showed an attenuated spike in acidity during high-intensity exercise. Moreover, the muscle-buffering function associated with beta-alanine intake has also been shown to improve strength performance, as illustrated in a study where subjects ingested either five grams of beta-alanine per day or a placebo for one month. The group receiving beta-alanine demonstrated significant improvements while performing a six-set 12-repetition squat workout using 70 percent of their one-repetition maximum, in comparison to the placebo group.14
3) Bicarbonate Buffers Outside the Muscle Cell
The bicarbonate system is one of the most important extracellular chemical buffers, attenuating a large majority of the acid released into the blood during intense exercise.15 The bicarbonate system also contributes to intracellular buffering by increasing extracellular pH— which promotes the diffusion of lactic acid out of the muscle cell, ultimately reducing intracellular acidity. Although bicarbonate is a natural buffering agent, the normal stockpile of bicarbonate in the body is relatively small. Therefore, to improve exercise performance, investigators have sought to enhance the bicarbonate system by increasing the rather low bicarbonate levels in the blood via supplementation.16
Most current research has shown that bicarbonate loading enhances performance during near-maximum intensity work lasting between roughly one and seven minutes.17 Since most resistance training is done at a relatively higher intensity for a shorter duration, it was first believed that bicarbonate supplementation might not positively influence muscle growth. However, another study by Carr et al.18 showed that resistance exercise designed to stimulate muscle hypertrophy also benefits from bicarbonate loading, as this type of resistance training similarly increases muscle acidity that can be buffered with bicarbonate— thus enhancing performance.
In the above study, 12 male participants ingested 0.3 grams of sodium bicarbonate per kilogram of bodyweight. The protocol employed four sets of 10-12 repetitions performing several different leg exercises at maximum loads, with short rest periods between sets to maximize lactic acid production. Exercise performance was determined by total repetitions where the group supplemented with sodium bicarbonate, which induced a significant reduction in muscle acidity, completed a considerably larger number of total repetitions than the placebo group.
4) Beta-alanine Plus Carnosine: A Potent Buffer
Although sodium bicarbonate has a positive influence on muscle performance, bicarbonate loading is accompanied by a few substantial side effects including nausea, vomiting and diarrhea that may preclude its use. These negative effects are likely due to the large quantity of sodium bicarbonate necessary to elicit an ergogenic effect (roughly 30 grams per day for a 220-pound person). While lower amounts of bicarbonate show no signs of performance enhancement when taken alone, it is conceivable that the buffering capacity from lower amounts of bicarbonate intake would be made more effective if consumed with carnosine. This is because the simultaneous consumption of carnosine buffers lactic acid in the muscle cell, which consequently lowers lactic acid efflux from the muscle cell. The lower amount of lactic acid outside of the muscle cell, as a result of carnosine intake, should be bufferable by a lower bicarbonate level. If true, this would reduce the amount of bicarbonate needed for effective buffering— which would mitigate the adverse effects from too much bicarbonate while likely permitting an even greater overall buffering capacity, due to the complementary buffering functions of these two compounds. In order to investigate this possibility, two recent studies19,20 looked at the use of either bicarbonate or beta-alanine alone or in combination. The studies showed that the co-ingestion of bicarbonate and beta-alanine had a strong additive effect on muscle acidity and exercise performance.
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