Athletes participating in high-intensity sports/events or in sports where athletes are required to make repeated high-intensity efforts have different performance-determining factors than other athletes. Lactate accumulation of more than 10 mmol/L is a result of anaerobic glycolysis, which is used to produce large amounts of adenosine triphosphate (ATP) energy in sports that require high levels of anaerobic activity. The wide range of qualities that are important for success in high-intensity sports is especially notable in middle-distance/high-intensity events, which require a mix of aerobic, anaerobic, and neuromuscular/mechanical abilities. Many of these qualities can be improved through nutritional interventions. There are many factors that limit high-intensity performance, but one major factor is the ability to tolerate increased levels of muscle acidity, both inside and outside of cells. Athletes have been doing research and using sodium-bicarbonate loading to improve their extra-cellular buffering for many years.
However, it was not until the mid-2000s that work by Prof. Roger Harris and colleagues showed that it was also possible to increase the buffer within the muscle by taking beta-alanine supplements for several weeks. This led to a significant increase in muscle carnosine (b-alanyl-L-histidine) and high-intensity performance. Since this time, there has been an explosion of research examining the efficacy of beta-alanine supplementation to optimally augment the muscle carnosine content and enhance subsequent performance.
LIMITATIONS TO HIGH-INTENSITY EXERCISE PERFORMANCE AND MUSCLE CARNOSINE MECHANISMS OF ACTION
High-intensity sports/events are unique because they require a lot of energy from both aerobic and anaerobic metabolism. The best way to provide ATP for high-intensity exercise is to use all three energy systems simultaneously. The anaerobic systems, phosphocreatine degradation and anaerobic glycolysis, provide ATP the quickest, but aerobic metabolism provides the most ATP overall. ATP production from aerobic metabolism cannot keep up with ATP utilization during the beginning of exercise and during situation with intensifying intensity. The lack of energy is supplied by anaerobic metabolism. -This energy is provided by the PCr system and the anaerobic glycolysis system. The process of breaking down glycogen in the glycolytic pathway produces pyruvate, which provides ATP. This process has a greater capacity than PCr degradation and is the primary source of ATP. This text is discussing how, during extreme-intensity exercise, pyruvate is produced at a rate that is too high for it to be oxidized aerobically by pyruvate dehydrogenase. This results in high levels of lactate production.
Skeletal muscle pH decreases from 7.2 at rest to 6.6 at exhaustion as a result of high-intensity efforts lasting ~4 min that are conducted at ~20-times resting VO2 values. This results in blood lactate as high as ~25 mmol/L and the production of hydrogen ions (H+). Although there are many Factors that can cause fatigue, there is evidence to suggest that muscle acidosis, caused by accumulating H+, is a key limiting factor in sustaining high-intensity exercise for 1-10 minutes. Carnosine was discovered over 80 years ago and is known to be a key buffer within cells. This is because it contains nitrogen in the form of imidazole, which allows it to accept hydrogen ions (H+) and slow the decline in muscle pH levels during intense exercise. Carnosine levels in normal muscle contribute around 6-7% to the total buffering capacity of muscle cells, but this can increase to around 15% when beta-alanine is supplemented. Notably, it has been common knowledge for the past 35 years that sprinters and rowers have approximately twice the amount of muscle carnosine as marathon runners. Furthermore, carnosine has a strong correlation with type II muscle fiber content. Severe metabolic acidosis can limit high-intensity performance, and muscle carnosine can act as one of the many intracellular buffers.
There are several factors that limit high-intensity performance, including metabolic acidosis, which reduces ATP production, as well as biomechanical and structural constraints. Many sports that require mid-distance or power-based performance also require extreme physical adaptations, such as very large thigh muscles in sprint cycling or rowing, which results in exceptional speed and explosive strength or power. The performance of these sports also needs to be considered from a structural and biomechanical origin, such as absolute peak force, rate of force development, and body mass. Running speed is limited by the amount of time needed to apply large forces. This is related to the amount of fast-twitch type II muscle fibers and/or the ability of the muscle to generate maximal force. Type Two muscle fibers have way more muscle carnosine than Type One fibers.
Although most of the support for carnosine’s proposed physiological roles has come from cell culture and rodent research, there is still some evidence to suggest these roles. Though these roles are typically thought of as happening in a laboratory setting, it’s likely that they also occur during human resting and exercise. The potential physiological roles of carnosine have been recently reviewed by Matthews et al. with the strongest mechanism for augmented carnosine in athletes being enhanced intra-cellular pH buffering. Secondary mechanisms for myocardial protection also include – calcium handling (release, reuptake, Ca2+ sensitivity) – the cytoplasmic Ca2+-H+ exchanger (also known as the carnosine shuttle) – the ability to regulate bioenergetics and glycolytic flux – scavenging of reactive oxygen species to alter oxidative stress – and the formation of stable conjugates to prevent reactive aldehydes and lipid peroxidation.
An interesting emerging mechanism is the carnosine shuttle hypothesis. Recent data from cardiac myocytes has shown that carnosine is not only a buffer, but is also involved in Ca2+ and H+ handling from the sarcoplasmic reticulum. This suggests that carnosine may play a role in human skeletal muscle, but this needs to be confirmed with further research.
BETA-ALANINE: A POWERFUL AND SAFE ERGOGENIC SUPPLEMENT
WHAT IS BETA-ALANINE?
This amino acid is not used to create proteins. It is classified as a non-essential amino acid because the body can produce it on its own in the liver. You can find it naturally in some foods, such as meat and poultry. Although the body does produce beta-alanine naturally, many people still choose to supplement with it.
Beta-alanine + histidine = carnosine = lactic acid buffering
If you want to improve your performance while working out, then taking a beta-alanine supplement can help. This is because beta-alanine is a building block of carnosine, and taking more than your body needs can increase the levels of carnosine in your skeletal muscle. Carnosine helps to prevent the buildup of lactic acid in muscles. Carnosine is made up of two amino acids: beta-alanine and histidine.
This amino acid is needed for the creation of various proteins and must be consumed through diet or supplementation. Histidine is found in many foods that are high in protein, such as meat, fish, poultry, nuts, and seeds. This makes it easy to get enough histidine through diet alone.
If histidine were also included in pre-workouts, it would be unnecessary because beta-alanine is already present.
Beta-alanine is the carnosine bottleneck
This means that without enough beta-alanine, your carnosine levels will be limited. If you don’t have enough beta-alanine in your system, carnosine production won’t happen as quickly, even if you have a lot of histidine. Numerous studies have demonstrated that taking a beta-alanine supplement bolsters carnosine levels in the muscles, while histidine has no such effect.
In addition to that, beta-alanine is not found in as many foods as histidine, so supplementation would be a more realistic option. groups that supplemented with beta-alanine saw This explains why most pre-workouts contain beta-alanine, and not histidine. This is because beta-alanine has been shown to be more effective than histidine in terms of improving performance. Histidine is not often found in intra-workout supplements.
The benefits of beta-alanine come from its ability to increase carnosine levels in skeletal muscle. This allows the body to sustain lower levels of lactic acid for longer periods of time.
There have been many studies investigating beta-alanine. Some of the most notable studies will be discussed below. But first, it may be best to cover two systematic reviews:
- Beta-alanine meta-analyses: best for 30 seconds to 10-minute events?
In 2012, a meta-analysis was published in the Amino Acids journal by researchers from Nottingham Trent University. The meta-analysis reviewed 15 studies with a total of 360 participants. The study found that people’s ability to exercise was improved, particularly for exercises that lasted between one and four minutes. Short burst exercises were not impacted by the research, which makes sense given the mechanism. This means that beta-alanine is most effective for long workout sets and mid-distance sports (eg 200 freestyle or 800-1600m races).
Brazilian researchers searched through extra data in 2016, studying 40 different exercise protocols with 65 total participants. They noted a significant overall effect from beta-alanine. The researchers found that the best effects from the music were between 30 seconds and 10 minutes long. This means that 100 freestyle and 400m dash are now an option!
Interestingly, the best results were yielded when co-supplementing with sodium bicarbonate, but we almost never see much sodium bicarbonate in beta-alanine-containing supplements.
The meta-analysis showed that highly trained athletes still had some benefits from beta-alanine, but not as much as untrained athletes.
The studies later on will show that there have been successful trials for both sprinting and longer endurance sports – especially for the sprints performed at the end of a race, which can often mean the difference between a few places.
Next, moving on to the individual studies:
- Increases in strength
A study published in 2018 in the Journal of the International Society of Sports Nutrition found that beta-alanine may improve athletic performance. The researchers’ goal was to see if taking beta-alanine supplements would make it easier for people to adapt to a resistance training program. The study recruited 30 healthy, resistance-trained volunteers and randomly assigned them to a placebo group or a beta-alanine group.
The BA group took a total of 8 capsules spread out throughout the day, each containing 800mg of beta-alanine. The PLA group followed the same protocol, however they used sucrose instead.
All participants underwent the same 5-week resistance training program. The main outcome measures of the study were:
- Average velocity
- Peak velocity
- Average power
- Peak power
- Load in kilograms in a back squat
- Incremental load
- One-repetition maximum (1RM) test
At the end of five weeks, the researchers found that in conjunction with a resistance training program, supplementing with 6.4 grams of beta-alanine per day significantly increased:
- Power output
- Work volume (overall number of reps, sets, and weights lifted)
- Strength (as measured by a one-repetition maximum)
It is important to note that nobody should be claiming that the supplement itself will directly increase strength. Instead of finding a difference in people’s blood circulation, the researchers believe that the results are due to beta-alanine’s ability to help people work harder. Beta-alanine supplementation increased participants’ weightlifting capacity over the course of five weeks. The added capability increased the strength in the above metrics.
- Improves work capacity
The researchers were trying to find out if taking beta-alanine for four weeks would increase the amount of carnosine in the muscles and how much work the cyclists could do. The study recruited 25 male volunteers and split them into two groups: beta-alanine and placebo.
The participants started by taking 4 grams of beta-alanine each day in week one, and then increased the amount they took to 6.4 grams in week four. The placebo group followed the same protocol, but instead of receiving the study drug, they received a maltodextrin solution. The volunteers cycled at a high intensity at the beginning and end of the study. The researchers also collected biopsies from quad muscles to assess changes in the levels of the amino acid carnosine.
The study authors found that, after four weeks, the BA group’s carnosine levels increased by 58.8%. The workers who took the supplement saw a significant increase in their work capacity compared to those who took the placebo.
Delays the onset of fatigue
A study found that taking beta-alanine not only increased work capacity by nearly 15% but also delayed neuromuscular fatigue onset after 28 days. Researchers from the University of Oklahoma recruited 51 untrained male volunteers for a double-blind placebo-controlled study and randomly divided them into four groups:
- Placebo: received 34 grams of dextrose
- Creatine monohydrate: received 5.25 grams of creatine plus 34 grams of dextrose
- Beta-alanine: received 1.6 grams of beta-alanine plus 34 grams of dextrose
- Beta-alanine plus creatine: received 5.25 grams of creatine, 1.6 grams of beta-alanine, and 34 grams of dextrose
The volunteers took their assigned supplement four times a day for the first six days, and then twice a day for the rest of the study. The subjects were given supplements, and then they were asked to do a continuous, incremental cycle ergometry test before and after taking the supplements. After 28 days, the researchers found that the beta-alanine and beta-alanine plus creatine groups had a significant increase in physical work capacity compared to the placebo group and creatine-only group.