Correlations: How The Media Ruin Science

We’ve all seen those headlines and articles claiming something along the lines of “Scientists prove that [food or beverage] causes [adverse medical condition].” For example, meat and cancer (which I debunked here).

The problem with a lot of these claims are that most of these things are not “proven” and there is usually not enough evidence to establish causality (one thing or action causes a certain effect to occur every time you have that thing or do that action). Many of these headlines pull their “facts” from a type of research known as observational study.

These studies essentially follow people and record a certain behavior or pattern and look to find any common trends between the people being observed to develop an association or possible link between “behavior X” and “outcome Y”. These are your meat and cancer studies or red wine and heart health studies (you’ve probably seen basic moms post about that one to justify their alcoholism, I know I have!).

Why does this matter you might ask? Well science gets reported often in the news and state and local representatives, in an ideal world, want to protect their constituents, so they will do what they can to service their community. If a study gets misreported by media claiming that meat causes cancer or dihydrogen monoxide is harmful to our health, then misinformation may be spread by the representative who is simply trying to help their community by banning water or meat because the public who watches the news demands they do something about this travesty!

Here’s another example of why we can’t rely on solely observational studies to make our decisions. Ice cream and drowning. Maybe you’ve heard this before. Ice cream sales are highly correlated with drowning deaths. This means that as ice cream sales increase, so do deaths from drowning. Does ice cream lead to drowning? Or do drownings lead to buying ice cream? Probably not for either. There’s something else at work here known as a “confounding variable” that is clouding the conclusion. Ice cream sales increase likely during the Summer and more people are also likely in the pool during the Summer, also leading to increased potential for drownings.

We have to be careful with news stories that reference research studies because observational research is popular among journalists because they can make bold claims like the ones mentioned before; however, as we’ve seen, those claims don’t actually hold up/are not what the study is actually saying.

On a related note: Be very careful of the word “proven”. Rarely is something proven in science by research and when it is, it has been studied over and over and over and over and over and over and…you get the point. It takes a long time, potentially decades, to establish causality or proof that one thing causes another. We can make associations about things, but causality is a completely different concept because it has to happen 100% of the time. If meat really did “cause” cancer, then there would be an actually be an outright ban on meat to protect the public; however, it’s only an association and it’s weak at that. Not everyone who eats meat will get cancer.

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To demonstrate how hard it is to prove something, consider this: Gravity is still a theory. Our explanation of why we observe the effects of gravity is only a theory, meaning we’re pretty sure but not 100% sure. So when someone says that science has proven that processed foods are cancerous or that this causes that, put on your skeptic hat because that person is probably speaking in hyperbole to argue their point rather than present fact.

You may have also heard that insulin causes obesity or “this one thing” causes obesity. Put your skeptic hat on for a minute: There are so many aspects to our lives that could contribute to weight and fat gain, how is it possible that we can pin all the weight gain for the billions of people that gain weight and fat every year? I’m willing to say that it’s impossible. While this may start to sound like a rant, I think it’s appropriate to say because many people will blame one issue when there’s a plethora of other potential things going on.

If you approach someone’s weight problem thinking that there’s only one underlying issue and you try to treat just that one thing, you’re probably going to fail because they could have other factors or behaviors in their life that could be adding onto the complexity of obesity. It’s also belittling to the person to say they just need to stop doing “x” and when they do it, they’re still obese. Don’t be a dick. Be an empathetic non-dick and realize obesity is a complex issue that has many potential causes and it’s up to the trainer or care provider to find those causes and help the person get through them instead of blaming insulin, processed foods, or their lack of motivation. That’s being a dick.

All of this leads to the famous phrase said by many people in the sciences: Correlation does not equal causation. I hope I’ve burned into your mind why this is. I also hope that, if you’ve stuck around for this long to read this (thank you by the way), then you understand to be more skeptical when you see a sweeping headline claiming causality or that science proved something.

Because if we can’t even be 100% sure about gravity, how the hell are we going to be sure about a food causing cancer? 

Thanks for reading! What questionable shit have you seen online or on the news?

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The Exaggerated Link Between Meat and Cancer

I know I’m not the first one to touch on this, but I see this still being an issue with the rise of vegetarian and vegan diets. Not to say I have a beef (ha) with people who eat this way, but the claim that red or processed meat causes cancer is one rooted in poor reporting of data.

Here’s the story: In 2015, the World Health Organization (WHO) published a report on meat and its links to causing cancer. They categorized red meat as “probably carcinogenic to humans” and processed meat as “definitely carcinogenic to humans”¹. Sounds scary, right? Here’s the issue with this: the WHO doesn’t measure how dangerous something is or the level of risk the item in question has; it measures the strength of the evidence to indicate that it’s carcinogenic (cancer-causing). While that sounds like the same thing, it’s not. If the studies aren’t well-conducted or not measuring what you’re looking for, then the evidence may be strong, but it’s not accurate.

Before we go further, I want to clarify the difference between “red meat” and “processed meat”. The WHO defines red meat as “all mammalian muscle meat, including, beef, veal, pork, lamb, mutton, horse, and goat”¹. Basically, any meat you see in clear packages that looks fresh from the animal. Processed meat is “meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation”¹. Think of hot dogs or turkey and pastrami slices.

Study Designs and Confounding Variables

The issue with the body of evidence about meat and cancer is that a lot of it is from what are known as epidemiological studies. This study design attempts to find the source of a disease by following a specific population over a long period of time (years, decades, lifetime, etc.) and see what happens to them. Through this, they attempt to find trends or common habits and behaviors that a lot of the population does as a potential explanation for a disease or condition.

For example, epidemiological studies have found a strong correlation between smoking and lung cancer formation. Through a different type of study called mechanistic studies, they have discovered the chemicals in tobacco that lead to the lung cancer over time from consistent inhalation of cigarettes. Of course, not everyone who smokes will develop cancer though, so we cannot say with 100% certainty that smoking causes cancer. Epidemiological studies cannot prove anything, just find associations.

Back to meat, the problem with these types of studies and meat consumption is that there are so many other areas and functions of a person’s life that could contribute to cancer formation that these external factors could be driving the cancer formation instead of the meat itself. For example, wealthier countries typically consume more meat than poorer countries. Wealthier countries and individuals can also afford more cigarettes; what if someone was smoking and eating meat but the study only was measuring for meat consumption. Was it the cigarettes or the red meat? This is known as a confounding variable. It’s something that cannot be accounted for in a study that may influence the result.

My personal opinion is that there are many confounding variables that are likely contributing to cancer formation in people who eat meat than the actual consumption of meat itself (meat eaters may be more stressed, unhealthier, sedentary, etc.). So while there is a correlation between processed meat and cancer, there are still so many things that could contribute to it, it probably would serve you better to move around more and eat better than to cut out your occasional deli sandwich or sausage.

Relative Risk

On the other hand, there have been some chemicals found in cooked meat that are carcinogenic, should we be concerned? Probably not and here’s why.

While the risk of red or processed meat and cancer risk has been quantified, the number is very misleading. On the Q&A page of the WHO website and in news outlets, you will see that you have an 18% risk of developing cancer if you eat processed (not red) meat daily. The nuance here is that 18% is a relative risk, not an absolute risk. What this means is that if your current risk of cancer without eating red or processed meat is 3%, then your risk of getting cancer moves up to 3.5% if you choose to eat red or processed meat daily. Why 3.5? Relative risk factors in the risk you already have and then multiplies that by the percentage of the new risk factor (18%). Here’s the actual math:

3% (expressed as a decimal is 0.03) x 18% (1.18 as a decimal because you’re adding the risk of 18% from the 3%, hence the 1 in front of the decimal)=3.5%. Try putting in your calculator 0.03 x 1.18.

So in theory, the risk of developing cancer from red or processed meat is very, very small. Almost insignificant. For that individual, the absolute risk of developing cancer from processed or red meat is 0.5% because their total risk of cancer increased by 0.5% after including the relative risk of 18%.

To clarify, the body of evidence for processed (not red meat) shows a strong link between daily consumption of processed meat and cancer risk, meaning that cancer-causing chemicals are most likely in these processed meat, but the risk of actually getting cancer from these chemicals is so small that there are many other things to worry about than the meat you’re eating. As for red meat, the evidence is not as clear as it is for processed meat. They think there could be a link, but confounding variables are still clouding the final decision. The following is a short concise list of a few more points I want to really hammer home quickly.

Quick Takeaways

  • People say processed meat is in the same category as smoking, so it should be just as bad. Again, this list only measures the strength of the evidence, not the magnitude of risk for the specific item. Smoking is very much more likely to lead to cancer than a hot dog is.
  • The 18% risk that is so popular to throw around is accounting for processed meat consumption on a daily basis. Chances are you’re probably not eating processed meat every single day.
  • There are may things in our lives that come with some sort of risk. And many things can cause cancer. What’s life without the things you enjoy? If you enjoy eating red or processed meat every now and then, freaking have it. If you’re afraid of getting cancer because you ate a slice of deli meat, your priorities are out of whack. My point here is there are many things that will kill you, cause cancer, etc. If you spend your whole life trying to avoid them, what kind of life are you living?

Final Points

Should you cut out red and processed meat? Probably not, as you read, the risk of getting cancer from these foods is very slim (even more slim from unprocessed red meat). Conversely, could you benefit from reducing your intake? Yeah, most likely! There are plenty of sources of animal protein that are not red meats which are still tasty and nutritious along with plant-based protein sources that can be often even more nutrient-dense. Many people could probably live healthier lives if they lowered their meat consumption (but not completely eliminated it).

It just simply does not make sense to completely cut out red or processed meat from your diet if you’re worried about cancer; because chances are, you’re probably doing something else in your life that is contributing more to your cancer risk than some meat. Just enjoy your damn food and don’t eat too much of any one thing. Drop a line in the comments about your thoughts or favorite meat-based recipes! Below you can find some other resources if you want to do more reading for yourself.

References

¹Q&A on the carcinogenicity of the consumption of red meat and processed meat

Additional Resources

WHO report says eating processed meat is carcinogenic: Understanding the findings

How to interpret IARC findings on red and processed meat as cancer risk factors

 

Bro Science: 1 Science: 0.5 (The Mind Muscle Connection)

It’s been a long thought among the bodybuilding community that, in order to maximize GAINZZZZ (aka hypertrophy), you need to establish a “mind-muscle connection”. What that means is the person who is performing the exercise is actively “thinking” about contracting the muscle as opposed to simply going through the motions. Now, in 2018, there is empirical evidence to support this idea.

The concept has long been touted by bodybuilders such as Kai Greene and Arnold Schwarzenegger (pictured here) that it’s essential to eek out those small, fine details of building muscle. Interestingly, last year at the International Society of Sports Nutrition Conference that was held in Phoenix, Arizona was the first time I heard about this study. Brad Schoenfeld, the lead researcher and OG of muscle science, talked for a short time about the findings of the study; however, since research takes a long time to publish, it was only recently made publicly available. So here we are! Let’s see what the study said!

To begin, let’s talk about where this idea fits in the scope of science. The broader term for this concept of mind-muscle connection is known as “Attentional Focus”¹. This is simply what floats through people’s minds while performing a task. It’s broken down further into an External and Internal focus¹. In a hypertrophy and bodybuilding context, an internal focus is what we consider the mind-muscle connection. It’s thinking about squeezing the working muscle and contracting it as hard as you can to “maximize gainz”. An external focus, the way I see it, is more motivational/supportive in that either yourself or someone else is keeping you focused on the outcome of the exercise¹. In this study, external focus was enforced by a trainer instructing the lifter to “Get the weight up!”, so you can see that it’s more focused on finishing the lift and completing the exercise as opposed to the muscle contraction¹.

“Okay, but how did they do it?”

Great question! The researchers took 30 males who were untrained (meaning they don’t normally exercise) and put them through 3 day/week training sessions for 8 weeks straight of barbell bicep curls and leg extensions (these exercises are easy to measure and isolate the muscles being studied)¹. As mentioned earlier, both internal and external groups were given different cues by the trainers depending on which group they were in (“squeeze the muscle!”) vs. (“get the weight up you weenie!”[no participants were called weenies during this study])¹.

Biceps and quadriceps muscles were tested to by an ultrasound machine for muscle thickness (MT)¹. MT is an indicator of muscle growth.

Side note: Could you imagine only doing curls and leg extensions 3 times a week for 8 weeks straight? I personally would get so bored! Applause to these guys who did it, because that sounds boring to me.

“So they made them do this boring routine..what happened?”

What happened next may shock you! (Are you tired of those headlines like I am?)

After the trial, the participants saw some interesting results. In the biceps, the internal focus group saw greater increases in hypertrophy over the external focus group¹ via increased MT. The study also found what was called a large effect size favoring the internal group for the biceps muscles¹. A large effect size basically reinforces that the cause of the increase in hypertrophy is actually because of the internal focus rather than something else.

The quadriceps muscles observed did not differ greatly in hypertrophy between both groups¹.

“But WTF does any of this mean?”

It means that the bodybuilders were right! However, this is only one study that has tested the mind-muscle connection theory in this manner with the machines and methods that they did. Nevertheless, this is exciting to see that the concept of actively thinking about contracting and “squeezing” your muscles may have some validity to it! Next time you’re in the gym doing some curls, benching, or leg curls, stop listening to your music and have that voice in your head (I know I’m not the only one) tell you to SQUEEZE!!! Try it for yourself! You may get more gainzzz that way.

A word of warning though: from my own experiences playing with this, I have had to use a lighter weight because the concentration does make the exercise feel harder, so you may want to try with a lighter weight than you normally do.

As for why there were no differences in the groups for the quadriceps muscles, the researchers offered a potential explanation for this phenomenon: Lower-limb muscles are not used for small, meticulous, and fine movements like muscles in the upper limbs are (think careful movements with your fingers and how precise you can be with the muscles and actions of them)¹.

We don’t have that precise control over our leg muscles like we do the muscles in our upper-limbs, so it may be more difficult to actually “squeeze” the muscles harder than you already do. Not to say that it’s impossible! Another reason might be because the subjects were untrained and had not a lot of experience exercising and learning how to “squeeze” the muscles like an experienced bodybuilder may have¹. I believe we would see a different picture if bodybuilders could be tested.

Takeaways

  • The mind-muscle connection has long been a theory among bodybuilders about thinking about the muscle you’re training to make it work harder and therefore, get more gainzzz.
  • This study supports the idea for upper-limb muscles only because that was the only area where internal focus (aka mind-muscle connection) appeared to make a difference.
  • Lower-limb hypertrophy may be greater if an internal focus is taken if the subjects are trained, but this study can’t say that. More research must be conducted first.
  • Consider trying it for yourself!

As always, thanks for reading!

References

¹Differential effects of attentional focus strategies during long-term resistance training

Flexing muscle with blue background graphic Created by Dooder – Freepik.com

 

How Are Nutrition and Politics Similar?

Hi everyone. This is a speech I performed at my local Toastmaster’s club. I talk about the parallels between nutrition and politics, specifically how we discuss them. I offer solutions at the end to mitigate the frustration and divide we see in these two areas. It’s not a perfect speech, and I will be refining it over time, but I think it has some useful information, so I hope you enjoy!

Chris Perry, MS | Setting the Record Straight About Sleep (Hint: GET MORE OF IT)

Welcome back to the Agora Bodkast! I’m very excited to share this episode with you! I really think it has a lot of valuable information. Chris really knows his stuff, and we dive into all aspects of sleep including naps, supplements, insomnia, whether fitbits and sleep trackers work, and ways to improve your sleep quality. There’s so much packed into this episode, I know you’ll get something out of it!

Don’t forget to head over to Itunes and leave a rate, review, and subscribe if you haven’t already! Thanks for watching/listening!

Show Notes coming soon!

How Do We Acquire and Use Energy From Food? Part 2

Welcome back to our discussion of energy systems! I appreciate you coming back and your desire to learn! That’s the whole goal of this website: to learn ya’ somethin’! Upon reading a comment from the first post, a reader enlightened me on my neglect to go into detail about what ATP is or what is stands for. So, before I dive into the final energy system, aerobic glycolysis, I’m going to briefly talk about what ATP is! Let’s begin!

ATP Revisted

ATP stands for Adenosine TriPhosphate. This is the molecule our body synthesizes from all these different energy systems in order to make us move in all the ways that we do. Chemically, it is composed of a DNA molecule known as Adenine (in this case, adenosine), ribose, and phosphate groups.

Adenine is one of the four components that create DNA (Only four things known as nucleotides make up your entire DNA sequence! That’s amazing!). Adenine then binds (connects) to ribose, a sugar molecule. Finally, this sugar is bound to a chain of 3 molecules known as phosphate groups.

What makes ATP the OG energy molecule is those phosphate groups. These are known as “High-energy bonds” that, when broken off the ATP molecule, release A TON of energy that our muscles, cells, etc. use to do all the activities that we do.

When a phosphate group is removed from ATP, it becomes ADP (Adenosine DiPhosphate) and AMP (Adenosine MonoPhosphate) when two groups are removed. Here’s a nice visual from Khan Academy¹ to summarize what I mean by molecules, phosphate groups, etc.

Untitled design (8)

Phew. Okay. That covers ATP. Now! Onto the star of the metabolic show, aerobic glycolysis!

Aerobic Glycolysis

Why do I refer to this energy system as the star of the show? This is the system that not only provides the most energy, but it is also in use the most amount of time because typically, we aren’t jumping, sprinting, etc. We only do that for a relatively short period of time (even though it may feel like it never ends).

When we’re just walking, sitting, working, doing normal people stuff, we’re using this energy system. ADDITIONALLY, this is the primary energy system in use when we’re doing light to moderate-intensity exercise for a long period of time.

What’s the reason behind this? Well, for everyday stuff, we’re not in dire need of energy at that very moment like we may be if we’re sprinting away from a bear or angry girlfriend (which are equally dangerous).

Our bodies are built for survival. If it doesn’t need energy ASAP, it’s going to break it down slower but provide more of that energy on a per-cycle basis. What I mean by this is for each “cycle” completed of aerobic glycolysis, we get more energy molecules, meaning more energy for us! Woohoo!

After the lactic acid cycle is depleted/unable to work further, this system kicks in for the remainder of the exercise. Interestingly, long-distance runners can actually notice when their metabolism “switches” to aerobic glycolysis. It’s characterized by fatigue, tiredness, and a feeling of “hitting the wall”. They feel this way because energy isn’t being produced as quickly as we need it.

Also a fun fact, this system is aerobic which means it requires oxygen to start working. Ever notice that you start breathing more the longer you exercise?? You’re taking in that oxygen for a reason. Your body knows when it needs oxygen, and so your brain will tell you to breathe more to take in more oxygen! BOOM!

Why does it take so long to acquire this energy? Aerobic glycolysis relies on fat consumed in the diet or from body fat stores once dietary fat is consumed in order to synthesize glucose and/or ATP. I say ‘and/or’ because when we use fat as energy, it actually breaks into its two components (glycerol backbone and three fatty acid chains, refer to this article on fat for a refresher on the structure of fats).

Glycerol produces a small amount of glucose while the fatty acid chains cannot be converted into glucose; so they have their own metabolic pathway to produce ATP. Creating glucose from sources other than carbohydrate (protein, glycerol, lactate) is known as gluconeogenesis². We actually saw this during the lactic acid cycle! Lactate becomes glucose during the cycle!

Back to the question, fat, as an energy source takes a while because of those damn fatty acid chains. These chains are composed of a lot of carbon atoms that go through a lot (a lot!) of steps to become usable energy. This metabolic pathway is known as Beta-oxidation or fatty acid oxidation.

Why Does This Matter?

Well I’m not going to teach you something if it’s not important! Also, this information will be on the test next Thursday, so make sure you study it.

It’s important because if you do long-duration exercise, you will be using this energy system for most of the time. Additionally, this is the system in use most of the time throughout daily life!

Yeah. So what?

So what? SO WHAT?! This is a sign for you to see that dietary fat is not bad for you. It’s an energy source that is very important for prolonged energy production! Also, if you know that you’re going somewhere without food for a few hours, having fat in a meal prior will help you stay energized. ‘Energized’ does not equal ‘full’ though, keep that in mind. Combat stomach emptiness with fiber and protein!

But, if you need energy for a long time because you won’t get to eat, having some fat from nuts, peanut butter, oils, avocados, seeds, etc. will keep you moving forward! THAT’S why this is important, dammit.

Here is a helpful graph from Precision Nutrition³ to summarize what these last two posts were about. I encourage you to read that linked article too. It’s super informative!

As you can see, ATP stores in the muscle are used up almost instantly, followed by the ATP-PC system (Creatine Phosphate) in purple, then the lactic acid system in green after about 2 minutes. Finally, aerobic glycolysis kicks in for the remainder of the activity at the expense of exercise or activity performance aka “Hitting the wall”.

Image result for energy system use over time

Takeaways

  • ATP is the primary energy molecule made of adenosine, a sugar molecule, and phosphate groups
  • Aerobic glycolysis kicks in after the lactic acid system and continues pumping out energy for the duration of exercise or the activity being performed.
  • Dietary fat and body fat are the primary fuel sources for aerobic glycolysis (Does not mean you can sit on your ass and claim you’re burning body fat. It doesn’t work like that.
  • When used for energy, fat is broken into two components that enter two different metabolic pathways (gluconeogensis for glycerol and beta-oxidation for fatty acids)
  • If you can understand what system is used, you can better prepare meals for exercise or if you’re going to be out for the day!

Do you like posts like this where I explain nutrition science topics?? I love talking about this stuff because I feel that science needs to be communicated to the public more often and in a better way. That’s one purpose of this blog if you couldn’t tell by now! Let me know what you think in the comments! All feedback welcome! Thanks for reading!

References

¹Basic concepts in bioenergetics: phosphoryl group transfers and ATP hydrolysis

²Glucose Can Be Synthesized from Noncarbohydrate Precursors

³All About High Intensity Interval Training (HIIT)

How Do We Acquire and Use Energy From Food? Part 1

Ever think about how we, as the crazy people we are, get energy to do everyday stuff? Walk, run, jump, pick up kids, throw said kids because they’re annoying, even getting out of bed! Everything you do takes some bit of energy!

Where do we get that energy? Caffeine? Well, it may seem like it, but caffeine provides no ACTUAL energy. It’s just a stimulant that makes you FEEL energized. There’s a huge difference. We derive our energy from food in the form of calories from carbs, protein, and fat (and alcohol)!

But, let’s dig deeper..how exactly does your body break food down into components that it can use for energy? More importantly, why is this important? Well, if you know what and how your body fuels itself, you can provide it better fuel at better times to feel better, without stimulants!

So, what gives us the energy to live the awesome lives we live? These awesome things known as energy systems!

Energy systems are typically discussed in the context of exercise because that’s one of the few times that all the systems may be utilized during one time period. Typically, at rest, only one (aerobic glycolysis) is used; but, keep this in mind, whenever you’re doing strenuous work like moving or lifting heavy objects, the other sports-related systems may be in use.

There are a few ways our bodies use the different fuel sources. It all depends on the activity you’re doing and the amount of energy needed to perform that activity. Let’s begin by talking about what our body actually uses as energy. Hint: It’s not glucose (technically).

ATP

ATP is THE energy molecule. Whenever we’re doing literally anything, we’re using ATP. While we can acquire ATP from different forms (carbs, fat, protein, alcohol, etc.), it all funnels into ATP and some other secondary molecules. This happens because we have different systems in our bodies to break down the different macronutrients. With that in mind, let’s talk about what they are, when they’re used, and why this applies to you.

In part 1 of this series, I’ll talk about the exercise-focused energy system, Anaerobic Glycolysis; but remember, whenever you’re doing intense, strenuous work, these systems are working, so don’t skip this if you don’t exercise! Part 2 will cover the more general system known as Aerobic Glycolysis.

Anaerobic Glycolysis

To begin, we discuss Anaerobic Glycolysis. This refers to systems that generate energy WITHOUT the use of oxygen. Oxygen is the primary distinction between aerobic and anaerobic systems. Oxygen as a chemical has some interesting properties to it that allows us to create energy in different ways. The next two systems-Creatine Phosphate and Lactic Acid Cycle-do not need oxygen to create energy. Let’s begin!

Creatine Phosphate System

This is the very first system used when doing typically high-intensity exercise or activity. Anything from deadlifting 1000lbs to picking up some heavy furniture. This system is used for, as Deadpool says, MAXIMUM EFFORT. Creatine phosphate is made up of a few atoms-the things on the periodic table-to make a molecule (Chemistry 101 lesson right there, you’re welcome). This molecule, Creatine Phosphate, will donate some atoms to make ATP.

All of this occurs inside the muscle tissues, so energy is able to be generated very quickly, hence why it’s used first; but there is a very limited supply of creatine phosphate in muscles, so this system will deplete in a matter of seconds. So why does this matter? Well, if you’re an athlete, or someone who just likes to exercise (running, lifting, etc.), then this is what jumpstarts you whenever you start your exercise! If you’re going to sprint, that quick jolt of energy is this system at work. Knowing what systems are at work can allow you to better fuel up for training! Creatine is most commonly found in meats. Vegans and vegetarians may have to supplement it.

Creatine supplements work by flooding your muscles with creatine, thereby allowing this system to last longer than a few seconds and continue to produce energy quickly which can lead to better training sessions since your endurance is improved! This is some seriously cool stuff. Think about it next time you pick up something heavy, or move some furniture!

Lactic Acid Cycle

After the Creatine Phosphate system is exhausted, the body shifts over to the lactic acid cycle for up to roughly 2 minutes of continuous work (think two minute run or two minutes straight of lifting). This is typically when someone will start to “Feel The Burn”, especially in terms of weight training. The reason this occurs is because there is an accumulation of hydrogen in the muscles, which causes the muscle tissue environment to become more acidic.

What this results in is that fatigue and tiredness experienced when lifting weights. The acidic environment inhibits the working muscles from contracting and causes that burning sensation and fatigue.

So why do we use this system if it’s just going to burn us? That’s some BS.

Not quite, dear reader!

The lactic acid cycle is great in its ability to produce energy quickly and for a relatively long time. If we couldn’t produce energy this way, we’d be pooped much quicker. Here’s how it works:

The cycle is between the working muscles and your liver. The things that are cycling are glucose and lactate. Remember glucose? That’s the primary source of energy and ATP and guess what? It still is in this case! As glucose enters the muscle cell, the glucose will produce some ATP for the immediate energy demand and then be converted to lactate.

Then, this lactate will travel to the liver to be converted back into glucose. When converted back to glucose, the lactate also produces some ATP for immediate use. The lactate (now glucose) will travel back to the muscle cell to produce more ATP and continue the cycle until the hydrogen atoms inhibit further muscle contractions.

As you can probably imagine, this system pretty much produces energy on demand, meaning that there is none stored for future use. The ATP that is synthesized is immediately used.

Takeaways

Once again, this system only lasts for a few minutes, then the aerobic glycolysis systems kick in and produces a TON of energy but at a slow pace. This will be the topic for part 2 next week! Stay tuned! Check out my other articles about the sources of ATP (Protein, carbs, and fat) to learn more about the awesomeness of our body’s interaction with food! Thanks for reading!

  • The body utilizes the macronutrients through different energy systems for different demands of energy
  • Higher energy demand is derived from anaerobic glycolysis systems
  • The Creatine phosphate system is the initial system used for high-intensity work but only lasts a few seconds
  • The Lactic Acid Cycle allows us to work at high intensities for a couple of minutes until muscle contraction is no longer possible. This is accomplished by cycling glucose and lactate between the liver and muscle cells.