Even with having 30 years of research on lactic acid there are still misconceptions that fitness professionals and the general public hold as truth.
The most common are:
1. It’s considered a primary cause of fatigue during exercise.
2. It’s the cause of delayed onset of muscle soreness (DOMS) which occurs 12-72 hours following exercise.
3. Regarded as a waste product of metabolism that would impair athletic performance if it was allowed to accumulate within the muscle cell.
These misconceptions can lead people to believe things about their athletic performance that is not true. By not understanding the body, we may not be getting the most out of our exercise.
Here’s what we’ve learned about lactic acid:
1. It serves as a viable energy reserve for both our aerobic and anaerobic pathways
2. It is true that accumulation of it during intense exercise can alter muscle pH and impede muscle contraction while simultaneously activating pain receptors (acute muscle pain), but this can normally resolve within 30-60 minutes following the cessation of exercise.
But what about that soreness we experience 1-2 days after a hard workout? Recent research shows that this has nothing to do with lactic acid, but is believed to be more aligned with micro trauma occurring within the muscle fibers due to excessive loads or volumes of eccentric muscle action. This would be the delayed onset of muscle soreness, or DOMS, effect.
Before explaining how the body really deals with lactic acid it’s important to know a couple of things first. First, lactic acid is produced as a by-product when glucose is metabolized and the demands of energy exceed the availability of oxygen. It is also a weak acid that dissociates in water. What comes of that dissociation is lactate which is a negative ion (L-) and hydrogen which is a positive ion (H+). Having these two ions in the body is what we’re referring to when we talk about lactic acid. What will be important to remember is that the H+ is what will lower the pH of tissues and blood which can cause problems if left unattended.
A buildup of H+ in the muscle will eventually stop the muscle from working. To avoid this accumulation the body combines extra pyruvate (made during the breakdown of glucose) with H+ to form lactic acid which we have learned is both L- and H+. This can then be removed from the muscle and placed into the blood thus allowing the muscle to continue working longer than it ordinarily can.
This is great news for the muscle, but what about the blood? If these ions were left unattended this would cause acidosis and could potentially impair or damage protein structures like red and white bloods cells, enzymes and hormones. Luckily, our body has a system to remove L- and H+ from the blood. Our blood has the capacity to tolerate these compounds due to buffers and the principal one is sodium bicarbonate (NaHCO3).
Once L- and H+ (lactic acid) levels get too high the sodium bicarbonate buffer can attach itself to the lactic acid which creates carbonic acid. This acid dissociates into water and carbon dioxide which is easily removed by the lungs. Another form of removal is potassium and sodium combining with the lactate which can be transported to the liver and other non-exercising regions to be converted into glucose which can be used for energy. These incredible processes not only keep the body safe but it’s also a great example of how to use lactate as a source of energy.
One other thing that is often confused are the terms ‘Lactate Threshold’ and the ‘Onset of Blood Lactate Accumulation (OBLA)’. It is often believed that if one has reached their lactate threshold they can no longer continue with intense exercise. One would assume this happens because the H+ levels in the blood are higher than the buffer can handle. Lactate threshold has been better defined as the first onset when H+ levels have increased in the blood but are still manageable. That means one could go on with their exercise. The onset of blood lactate accumulation is what happens when further increase of exercise intensity continues to raise L- and H+ levels, suggesting greater disruptions between lactate spill over and removal from blood. This leads to a disproportionate increase in blood lactate and subsequent acidosis due to elevated levels of H+. At this point the ability to perform high intensity exercise cannot be sustained for much longer. So yes your body can reach a point that it would need to stop but this keeps you safe and healthy.
It is important then to incorporate good recovery even while exercising. Doing this in between your sets can insure you do a little bit more without sacrificing your form. To increase the time before your reach your lactate threshold and OBLA doing aerobic type of exercise will help the former and anaerobic, or interval training, will help the latter. And for those sore muscles? Get our your foam roller!
The information for this article comes from, ‘The Lactic Acid Lowdown: Clarifying Common Misconceptions’ which can be found on the blog by the National Academy of Sports Medicine