Endurance sports: Amino acids and electrolytes to support exercise and recovery

Endurance sport: the role of amino acids and electrolytes.
I have been reading many posts from endurance sports where people report that they were feeling “pretty wasted” after their training or competition. This can include experiencing brain fog, trouble concentrating and of course muscles which are complaining loudly.
I have spent more than 30 years in university research trying to understand the basis for fatigue and how the recovery processes work. I thought I would share some of the insights which I have accumulated over the time that might help you better manage hydration and improve your recovery prospects. Here are some short sections focussing on the key elements of maintaining good condition.
The volume of sweat:
The first concept is understanding what you lose through sweat. Most people are well aware of the importance of taking fluid and electrolytes when undertaking prolonged exercise. The water in the sweat evaporates to help you stay cool  – this is an important mechanism for maintaining body temperature.

Did you know that you can easily lose 1-2L per hour in sweat?
As little as a 3% loss of hydration can lead to lack of energy, difficulty in concentrating, sub-optimal brain function and an overall loss of up to 50% decrease in performance.
Critical fact: Did you know that you also lose high-demand amino acids in sweat? These amino acids are central to helping with performance and recovery.
What is in sweat?
When you sweat, you can lose 1-2L of fluid per hour. When the water from sweat evaporates, it leaves behind the electrolytes and amino acids on the skin surface. When it is more humid, the evaporative cooling is not as effective.
To achieve hydration, you need to replenish what you lose in sweat, which includes: fluid, electrolytes and amino acids. The diagram shows relative proportions of each electrolyte and amino acid. The electrolytes include: Sodium (Na); Chloride (Cl); Potassium (K); Magnesium  (Mg); Calcium (Ca)
First Point: most electrolyte drinks do not contain all of the electrolytes required.
The amino acids include: Histidine, Ornithine, Serine, Lysine, Glycine and Aspartic acid
Second point: NONE of the electrolyte recovery drinks contain the necessary amino acids.
The quantity ranges give you a gauge for replenishment requirement – this is especially important for endurance athletes.
From our studies of amino acids in sweat, our research leads us to understand that the body loses six high-demand amino acids at faster rates than any other amino acids.

In addition to protein synthesis, these key amino acids, which are being lost at faster rates, are also used in multiple and other important aspects of metabolism, including:

  • Hormone production
  • Formation of neurotransmitters
  • Formation of DNA
  • Folate metabolism
Amino acids are the building blocks used to make proteins. When you eat proteins, you break them down via digestion to release the amino acids that your body needs for various processes and to make its own proteins.
* Digestion does not work very effectively during strenuous exercise and it takes some time to switch back into gear.
During exercise, a large proportion of the blood flow is diverted away from the digestive system towards the muscles to provided increased capacity from providing oxygen and nutrients as well as removal of waste products. So how does the body get the amino acids it needs to sustain exercise?

It breaks down its own muscle proteins to release the amino acids. This is great and very effective in the short term, but if you are working hard for extended periods, then this can be significant for your muscles – if you over train, body may resort to breaking down the muscle fibre proteins themselves.
High-demand amino acids

The latest research has identified that the body has a group of high-demand amino acids that are used extensively for exercise metabolism and are also lost in vast quantities through sweat (and urine). The body is trying to keep up with supply of these high-demand amino acids by breaking down its own muscle proteins, but in doing so it is also releasing the other 14 lower-demand amino acids, which include the BCAA. These other amino acids are not needed in such high demand by the body and they get used for energy, are recycled, or lost in sweat. Once the essential amino acids have been used for energy or excreted, they have to be re-supplied via the diet. This is why many studies have found that BCAA supplements can assist recovery from exercise.
You may ask: How can a couple of grams of amino acids lost in sweat make a difference in someone who weighs 70Kg?
Especially when you are eating a healthy diet with 90+g protein per day.
To answer this, consider your circulating blood as a reservoir of nutrient resources for the body’s muscles and organs to draw on as required. The body goes to great extents to maintain these levels of nutrients for constant supply to the tissues. If you lose amino acids or electrolytes in sweat, they need to be replenished.
You would have around 1 gram in total of amino acids circulating in the blood plasma at any one time. If you are losing 1-2 grams of amino acids in sweat every hour, then your body has to restock the entire reservoir up to two times per hour just to counter the losses in sweat. This replenishment can only come from the breakdown of your muscle proteins.
To give you some further context, if you lose 2g high-demand amino acids via sweat in an hour, it will take the breakdown of 10g of muscle protein to replenish them. You can see that this is a big call on your muscle’s protein reserve when you want conserve resources for endurance.

On the scale of things, the mass lost in this process is very small – 0.007% to 0.01% – but if you don’t allow for full restoration between training/competition, then these losses can become accumulative. The impact will be greater in women since the levels of amino acids in sweat are usually higher, and women generally have a lower percentage of muscle mass.
The importance of histidine in regards to a healthy supply of haemoglobin and carnosine.
Histidine is one of the 6 HIGH-DEMAND amino acids needed most on a daily basis. It is one of the most abundant amino acids present in sweat and urine.
  • It is also essential for the production of haemoglobin – great for performance and can also help reduce anaemia.
  • It is used to form carnosine which is vital for muscle performance.

Studies have shown that if you deprive people from histidine, then they become anaemic – when you restore the supply of this essential amino acid, then the anaemia is resolved.

The supply of essential amino acids such as histidine from plant proteins are largely similar to those found in meat proteins, with minor variations observed between sources. This comparison is based on evaluations of the amino acid compositions in extracted meat proteins.

  • But these do not normally take into account the fact that the meat is literally bathed in a compound called “carnosine”. Carnosine is made by the body to enable proper functioning of the muscles and brain, where one of its roles is to act as an anti-oxidant.

Carnosine is made up of the amino acids histidine and beta-alanine, and when you ingest carnosine, most of it is broken down by digestion to release an important source of the histidine.

Histidine is an essential amino acid and a good supply is required to maintain good health, particularly if you lead a very active lifestyle. In particular, an adequate supply of histidine can help to prevent anaemia by facilitating the formation of haemoglobin.

There is no equivalent source of extra histidine in plant resources.

Histidine can therefore become an important nutrient to take as a supplement when meat intake is limited or non-existent.

Major summary points from our research:
Several people have requested links to our publications and research findings. Here is a summary of our research on sweat and the publications can be found by using the doi links.

Implications of sweating

  • Large losses of Key Amino Acids occur in sweat
  • A group of 6 amino acids are lost at disproportionately faster rates than the others
  • There are different types of sweat losses
    • Higher volume with lower concentrations of amino acids
    • Lower volume, but higher concentrations of amino acids
  • Considerable quantities of these key amino acids can be lost
    • 1-2 L of sweat can be lost per hour during exercise.
    • Manual laborers can lose 10 L of sweat per day in a hot climate
  • Current research is investigating possible links between the losses of amino acids in sweat with the processes of resorption of sodium and chloride in the sweat glands.

Peer-reviewed & published papers

  1. Sweat facilitated amino acid losses in male athletes during exercise at 32-34°C. PLoS ONE, 11(12). doi:10.1371/journal.pone.0167844
  1. Relationships between electrolyte and amino acid compositions in sweat during exercise suggests a role for amino acids in reabsorption of Na+ and Cl- from sweat. PLOS ONE 14(10): e0223381. https://doi.org/10.1371/journal.pone.0223381
Finding out how much supplement is enough
  • A small group of key amino acids can become limiting during daily exertion resulting in a restricted supply of amino acids at critical times of demand. These limitations can be exacerbated with:
    • High intensity exercise
    • High levels of exertion at work
    • Living in a warm-hot climate
  • The results provided a scientific basis to explain how small quantities of the key amino acids could provide benefit to assist in the recovery from daily exertion and high intensity exercise.

Peer-Reviewed & Published Paper

Modelling of protein turnover provides insight for metabolic demands on those specific amino acids utilized at disproportionately faster rates than other amino acids.

Amino Acids. doi:10.1007/s00726-019-02734-1

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