Let’s face it lactic acid has a bad rap! Amongst the many accepted (negative) beliefs relating to it are these:

• Causes pain during exercise.
• Limits your performance causing you to stop or slow down or have a break.
• It is a “waste” product and serves no purpose.
• It gives you sore muscles the next day after exercising.
• Makes you feel like throwing up or actually doing it.

For a long time (since the 1920’s in fact) lactic acid was widely believed to be responsible for having these effects. The accepted theory in sports and exercise science was it was a waste product produced by the muscles due to hard exercise. This acid caused the muscles to stop working effectively and had numerous negative side effects, some described above.

Research in the last 10-15 years has slowly been busting many of these myths and changing long-held misconceptions about what it actually is, its role and its impacts.

Let’s look at the main four myths out there:

Myth 1: It’s produced by the muscles when you do hard exercise.
There has long been a belief that lactic acid was produced in the working muscle as the intensity of the exercise increases and the anaerobic energy system takes over from the aerobic system. This occurs as the supply of oxygen is not meeting the demands, and it was believed that lactic acid was produced in this process in the working muscles (e.g. legs if you were cycling or arms and shoulders if you were grinding).

The problem here is that “lactic acid” is not produced in the human body. Our muscles produce lactate, which is not acidic (see the box for a brief explanation). Over the years these two terms have come to be used mistakenly to mean the same thing, when in fact they are two very different chemicals - both with different roles and effects.

Myth 2: It causes the “burn” in muscles.
As we move faster or put greater strain on the muscles (greater demand) our body responds by changing the source of fuel production (supply) from the efficient aerobic system to the more powerful but less efficient anaerobic systems. One of these inefficiencies is the production of hydrogen ions (as a by-product of the chemical process in the working muscles).

These ions produced are acidic and they create an acidic environment - this impacts by making you less efficient (supply not able to meet demand) and ultimately will lead to you having to reduce the intensity of movement or stop moving altogether. It is these ions that causes the burning feeling in the muscle and sometimes a nauseous feeling in the stomach, as the body cannot cope with their effects.

Myth 3: It’s a waste product.
So we just learnt that lactate is not a “waste” product” - in fact it is quite beneficial and assists the body to work at high intensities. It does this by playing a role in removing other “waste” or by-products produced in creating energy in the working muscle.  Recent research is now confirming that lactate in fact can be used in the body as an energy source to fuel aerobic exercise.

Myth 4: It is the cause of soreness the next day after hard exercise.
Lactate will clear itself from your system about an hour after you stop exercising. This process can be slightly sped up by doing some light aerobic activity as a warm-down after exercise.

The soreness you may feel the next day after a hard workout is most likely due to the microscopic damage and inflammation in the muscle fibres that were recruited. This normally is felt about 12-48 hours after a hard session and can be felt for around 6-24 hours, depending on the individual response. This is known as DOMS and as you train more regularly your body will become accustomed to the stress and the soreness will become less frequent and less painful.

As we can see lactic acid doesn’t deserve its reputation as the “bad guy” of exercise. It is in fact quite necessary and useful in assisting our bodies to exercise for longer at higher intensities.

How to deal with it.
Basically –get fitter! Simple, I know, but as you get fitter you increase your work capacity and also your efficiency in producing energy. This means you can work harder for less effort or “cost”. By exercising regularly at higher intensities (with increased levels of lactate), your body will adapt and be able to handle it.

This is best done through interval training and maintaining intensity for a period of time slightly below your maximum. For example, maintaining 80-85% of your maximum for 5-10 minutes will gently and efficiently push your lactate threshold up to higher levels. Then slow down or lower your intensity for 5-10 minutes before increasing back up again. Start with 2-3 of these intervals in a workout and build them up to say 4-5 repeats.

Always finish with a warm down at a low intensity to help the body clear the waste products that you have created and return to a steady state and lower heart rate.

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