Lactic Acid vs. Lactate

Let’s say you run as fast as you can for a minute. The first 10 seconds or so are pretty easy, but then you can’t run as fast anymore. With each passing moment your muscles burn a little more, and your speed slows. What’s happening?

We’ll start with those first 10 seconds that were relatively easy, when your speed was fastest. The first one or two seconds were fueled by the ATP stored within your muscles. Then the next five seconds were primarily fueled by your phosphagen system, which is stored phosphocreatine (PC) within your muscles. So those first seven seconds came from a combination of ATP and PC, and that’s why it’s sometimes called the ATP-PC system, instead of the phosphagen system. Different name, same thing.

Before we move on, it’s worth noting here that even though the phosphagen system is typically described as lasting 10 seconds, in reality it can last up to 30 seconds, depending on the athlete and his/her previous training.

Enter Anaerobic Glycolysis
You know that you can’t run at your top speed, or perform a maximum isometric hold, for more than 10 seconds before things start heading south. That’s because your body’s quickest, “cleanest” energy source, the phosphagen system, has been taken over by your next quickest source for energy: glucose.

How does the body get energy from glucose? Let’s briefly cover a little biochemistry.

The foundation of the glucose molecule is a six-carbon structure. Those six carbons are split into two, three-carbon molecules, which are pyruvate. So anaerobic glycolysis consists of splitting one glucose molecule into two pyruvate molecules.

This splitting forms two adenosine triphosphate (i.e., 2 ATPs), which the body uses to make energy. Importantly, splitting glucose into pyruvate is fueled by NAD+. You might not be familiar with NAD+ but it’s essential for life and present in every cell of your body. After fueling the split, NAD+ turns into NADH. Importantly, glycolysis also releases an acidic proton (H+). The importance of this will make sense shortly, so hang with me.

Anaerobic glycolysis takes place in the sarcoplasm, the muscle’s gel-like substance that includes all of its components, except for the mitochondria.

Enter Lactate
So now you know that splitting glucose (i.e., anaerobic glycolysis) results in the formation of pyruvate and NADH. If you’re wondering what those molecules have to do with lactate, here’s your answer: Pyruvate and NADH are what form lactate. But for this to happen the enzyme, lactate dehydrogenase, is required.

Enzyme reactions work like a lock-and-key mechanism. In this case, the “lock” is lactate dehydrogenase, while the “keys” are pyruvate and NADH. Once those keys are inside the lock, NADH donates its proton to pyruvate. This transforms NADH into NAD+ and pyruvate into lactate.

Importantly, pyruvate consumes an acidic proton (H+) from the muscle during this reaction. Therefore, the formation of lactate is alkalizing to the muscle. Indeed, if it weren’t for the formation of lactate, your muscles would become even more acidic, as shown below.

What Happened to Lactic Acid?
Before we move on, you probably noticed that there’s been no talk of lactic acid. That’s because there’s very good research that demonstrates lactic acid isn’t formed in muscle, at all. You can find that research here and here and here. In a nutshell, lactic acid was discovered in the 1770’s by a scientist that was researching sour milk. Since it has a mildly acidic flavor, and can function as a preservative, lactic acid was later added to foods, as well as brewing and flavoring beer.

More About Lactate
Lactate is everyone’s favorite scapegoat. It’s been blamed for everything from the painful “muscle burn” to fatigue to muscle soreness. It’s not directly responsible for any of those things. In fact, lactate can be used to fuel muscle contractions, which keeps your efforts going. It can also be sent to the liver where it’s converted to glucose (i.e., gluconeogenesis), and then sent back to the muscle to continue with anaerobic glycolysis.

So lactate is your friend, but he hangs around with shady characters. The problem with lactate is that it’s always accompanied by protons (H+), even though it consumes one during each lactate dehydrogenase reaction. Proton accumulation is actually due to the breakdown of ATP (i.e., ATP hydrolysis) in muscle. When muscles are contracting intensely they require a lot of energy from the breakdown of ATP. This causes a huge release of protons (H+) within the muscle, but the lactate dehydrogenase reaction can’t consume enough of those protons to offset the acidity (i.e., metabolic acidosis).

That proton accumulation is what causes “muscle burn” and nausea since the pH of the muscle and blood are decreasing (i.e., becoming more acidic). Protons also decrease the speed and force of your muscle contractions. Therefore, lactate is guilty by association.

This is why scientists study the rate that lactate increases during intense exercise. The measurement gives them an idea of how much H+ is being accumulated. Because if lactate is increasing, so are protons.

The point where lactate starts to rise rapidly is the lactate threshold. As this level gets higher, your speed and power drop off substantially. Therefore, the goal of any good strength and conditioning program is to train your athletes to sustain more speed and power before hitting their lactate threshold (you can find the general training parameters in my last blog). The following graph gives you a visual of what I’m talking about.

So now you know a little bit more about lactate, and why H+ accumulation should be avoided to keep your power running strong. Speaking of power, my latest book Powerful Mobility is now available on Amazon for only $9.99.

Want some more scientific info about lactate? Check out this research.

Stay Focused,
CW

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(Note: this article has been modified since it was originally posted on 9/20/2017.)

Is Tabata Ideal to Build Endurance?

In the 1990s, two landmark research papers were released that drastically shifted how athletes and fitness enthusiasts train for endurance.

In 1994, Prof. Angelo Tremblay’s research demonstrated that endurance exercise performed with alternating bouts of high- and low-intensity resulted in better fat loss than continuous low-intensity exercise did.

Then in 1996, research by Prof. Izumi Tabata tested a protocol that consisted of 20 seconds of maximal activity, followed by 10 seconds of rest for 8 rounds. It was a gruesome four minutes for the athletes in the study. This Tabata protocol was compared to traditional lower-intensity endurance exercise performed for 60 minutes straight. At the end of the study, the continuous lower-intensity exercise group only improved their aerobic capacity. However, athletes that did the Tabata protocol increased both their aerobic and anaerobic capacity.

These two studies have been often quoted as “proof” that high intensity interval training (HIIT) is better than longer, slower cardio for improving fat loss and overall endurance.

Now, assuming you’ve tried HIIT using plenty of effort, you know that it quickly acidifies your body. Your muscles burn, and nausea can set in fast. This is not due to lactate, a substance that actually helps muscle contractions. It’s due to the accumulation of acidic protons (H+), which happens when the body starts burning a lot of glucose to make energy from glycolysis. With a higher effort and intensity, more glucose will be used, and subsequently, more H+ will be produced. This is how metabolic acidosis occurs.

There are two potential problems with making your body use more glucose for energy. First, you’ll gas out quicker than if you used fat to produce energy. When you see a boxer lose his energy and coordination in later rounds, he’s primarily using glucose, not fat, for fuel. A lean athlete has enough stored fat to fuel a jog that lasts for many days. Second, and maybe most importantly, we don’t yet know what negative impacts can occur from forcing the body into metabolic acidosis multiple times per week.

Enter Pavel Tsatsouline
Many of you will know Pavel Tsatsouline, chairman of StrongFirst, as one of the world’s top experts in building strength and flexibility. What you probably don’t know is that Pavel has spent the last three years immersed in endurance training research. His ability to read Russian gives him an advantage since some of the best endurance research has come from there.

Pavel and I have had many discussions over these last three years as he was perusing endurance research from around the globe. In those discussions, he effectively made the case for why many of the popular high-intensity endurance protocols aren’t ideal. Therefore, over the last year I’ve shifted my approach to building endurance with athletes. The results have been extremely impressive, which I’ll discuss more in future blogs.

I got to see Pavel publicly present his immense research for the first time this summer in Denver. His sold-out Strong Endurance seminar attracted some of the heaviest hitters in the fields of strength, conditioning, and physical therapy.

Pavel started off the seminar by warning us not to “chase the proton.” The acidosis that accompanies proton accumulation can lead to many problems that negatively affect power, health and performance. He went on to tell us that world-renowned Russian sports scientist, Prof. Yuri Verkhoshansky, figured this out many decades ago, dating back to 1980. In 1988, Verkhoshansky wrote this about his “anti-glycolytic” training:

“[Yet] the goal is not taking the athlete to exhaustion to accustom him to metabolic acidosis, as it is often understood in athletic practice, but just the opposite…to develop alactic power and to couple it with oxidative phosphorylation, to increase the muscles oxidative qualities, this is develop the local muscle endurance.”

What Should You Do?
The approach to building endurance without overemphasizing glycolysis is beyond the scope of this blog. However, there are two things to keep in mind when you work to build endurance.

1. Build your phosphagen system: Your muscles immediate source of energy comes from stored ATP and the ATP-CP system. They will fuel your maximum effort and speed exercises for 6-12 seconds. This means you can either do low-rep sets of strength exercises or high-speed work for 6-12 seconds. Give yourself enough rest to return your heart rate close to what it was at the beginning of the set to offset H+ accumulation.

2. Train endurance at your anaerobic threshold: If you perform endurance work in the anaerobic zone your muscles will need more oxygen than they can get, and this causes H+ and carbon dioxide (CO2) to accumulate. Both of these factors can increase metabolic acidosis. Dr. Philip Maffetone, author of The Big Book of Endurance Training and Racing, recommends training at a heart rate that’s around 180-your age. Therefore, a 30-year old athlete would perform his sport and endurance work around 150 beats per minute, allowing him to use fat for fuel and minimize acidosis. Over time he’ll be able to perform faster and faster at that heart rate.

This approach follows what Pavel told us all in his Strong Endurance seminar, “Increase your 100% and learn to use a lower percentage of it.”

Stay Focused,
CW

P.S. Click the image below to find out more about my 10-week Corrective Exercise certification course I designed for the International Sports Sciences Association (ISSA):