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  • Writer's pictureDoug Joachim

Correlation v. Causation in Fitness Studies: What You Need to Know


problem with fitness studies

Ah, fitness studies. The holy grail of discovering how to lose that last stubborn pound of belly fat, gain muscle like the Hulk, or find the ultimate secret to eternal youth. But, dear reader, before you jump into the rabbit hole of fitness research, let’s take a moment to address one crucial aspect that often leads us astray: the difference between correlation and causation. If you're thinking, "What’s the big deal?" allow me to explain in a way that won't put you to sleep:


Correlation: The Guilty Bystander

Picture this: you notice that every time you eat a kale salad, it rains the next day. Fascinating, right? You might even start believing that kale has some mystical power to control the weather. But, as much as I'd love to blame kale for ruining my sunny days, this is a classic example of correlation, not causation. Correlation means that two things happen to occur together, but one doesn’t necessarily cause the other. It's like seeing Batman at every crime scene and thinking, "Wow, Batman is causing all these crimes!" When in reality, he’s just there to save the day.


Causation: The Real Culprit

When it comes to causation, the relationship between events is not always as straightforward as dropping a dumbbell on your foot and feeling pain. In the realm of fitness studies, establishing causation is a complex and intricate process that often involves meticulous attention to detail and a thorough understanding of various factors at play. Researchers must design controlled experiments that account for all variables, conduct rigorous testing to ensure the reliability of results, and sometimes rely on a stroke of luck to uncover causal relationships.


Furthermore, proving causation in fitness studies requires a deep dive into the intricate web of interactions between different physiological, psychological, and environmental factors. It involves exploring how specific interventions or behaviors lead to particular outcomes, and teasing out the cause-and-effect relationships amidst a sea of confounding variables. This process is akin to searching for a needle in a haystack, where every detail matters and every potential influence must be carefully considered.


Ultimately, achieving a solid understanding of causation in fitness studies is not just intellectually satisfying but also crucial for informing evidence-based practices and interventions.


It is All So Confusing

Nearly everything you've been told about the food you eat and the exercise you do, and their effects on your health, should be met with skepticism.


Every week, dozens of studies make headlines, but they rarely satisfy our desire for clear answers about diet and exercise. Does exercise help prevent Alzheimer's? What kind—walking, running or resistance training? Do carbs make you fat? Can exercising as a teen prevent breast cancer? Do vegetables protect your heart?


The problem lies in the signal-to-noise ratio. The beneficial signals—like reduced dementia risk, longer life, less obesity, or less cancer—are often drowned out by the overwhelming noise from the vast uncertainties in measuring exercise and diet accurately. These signals are usually weak, meaning lifestyle effects are minimal compared to something like the clear link between smoking and lung cancer.


Additionally, there’s no universal gold standard for measuring lifestyle aspects, leaving us without a consistent benchmark.


Why Should You Care?

You might be wondering, “Why should I care about this correlation vs. causation mumbo jumbo? I just want to know if drinking celery juice will turn me into a Greek god!” Well, my friend, understanding this difference can save you from falling for fitness myths, wasting money on snake oil supplements, and potentially harming your health.


Therefore, by grasping the nuances of correlation vs. causation, you empower yourself to make well-informed choices that align with your health goals. It's not about dismissing the potential benefits of celery juice or any other health trend, but rather about approaching them with a discerning eye and a deeper understanding of the science behind the claims. Ultimately, this knowledge can be your armor against misinformation and help you navigate the complex landscape of health and wellness with confidence.


Fitness Studies and the Trap of Correlation

Fitness studies often come with big, bold headlines that promise miraculous results. “Scientists Find Eating Chocolate Helps You Lose Weight!” Sounds too good to be true, right? That’s because it probably is. Studies like these often report correlations – maybe people who eat chocolate also happen to exercise more or have other lifestyle factors that contribute to weight loss. It doesn’t mean that chocolate is the magic fat burner we’ve all been waiting for. Here is a quote from the author who intentionally duped the peer review process and got his study published about how chocolate helps weight loss:


"Here's a dirty little science secret: If you measure a large number of things about a small number of people, you are almost guaranteed to get a 'statistically significant' result. Our study included 18 different measurements -- weight, cholesterol, sodium, blood protein levels, sleep quality, well-being, etc. -- from 15 people. (One subject was dropped.) That study design is a recipe for false positives....We didn't know exactly what would pan out -- the headline could have been that chocolate improves sleep or lowers blood pressure -- but we knew our chances of getting at least one 'statistically significant' result were pretty good.

The Egg Conundrum

Take the case of eggs. You’ve probably seen headlines like, “Eating Eggs Will Kill You!” and thought, “Perfect, I’m going to die tomorrow.” But hold your horses. Egg eaters might die earlier due to a myriad of factors – maybe they have less active lifestyles, worse social networks, or perhaps the eggs are typically eaten with bacon, white toast and a cigarette. The point is, without controlled studies proving causation, these findings should be taken with a grain of salt.


NOTE: Evidence from high-quality studies suggests that eggs have a positive or neutral impact on health markers and do not pose a risk when eaten regularly as part of a balanced diet. They are a nutrient-dense, affordable source of high-quality protein, vitamins, minerals, and antioxidants that support muscle growth, brain function, and heart health. They're versatile, delicious, and can help with weight management while being environmentally friendly.

How to Spot the Difference

So, how do you, an intrepid fitness enthusiast, tell the difference between correlation and causation in studies? Here are some tips to keep you on the right track:


  1. Look for Controlled Experiments: Studies that use control groups and random assignments are more likely to establish causation. If a study merely observes trends without controlling variables, it’s likely reporting correlation.

  2. Check the Sample Size: A study with a small sample size might not be reliable. A study with a small sample size may lack the statistical power to draw meaningful conclusions. Larger samples tend to provide more accurate results. Fitness studies have notoriously low samplings.

  3. Beware of Confounding Variables: These are hidden factors that might influence the outcome. For example, a study might find a correlation between wearing yoga pants and flexibility. But the confounding variable here could be that people who wear yoga pants are more likely to practice yoga.

  4. Read the Methodology: Dive into how the study was conducted. If it’s well-structured with clear parameters and controls, it’s more trustworthy.

  5. Seek Peer Reviews: Studies published in peer-reviewed journals have undergone scrutiny by experts in the field. They’re generally more reliable than those that haven’t been reviewed.

  6. Poorly Designed Research: Tendency of different researchers studying the same effect to use different measurements and report outcomes differently, and researchers’ tendency to selectively report positive or “interesting” results.

A Humorous Anecdote

Let me tell you a funny anecdote from my fitness journey. There was a phase, in college, when I believed that smoking a little marijuana before my workouts made me perform better. Why? Because every time I did, I felt like I worked harder and was more focused during my lifts. I was ready to claim marijuana as the ultimate pre-workout supplement until I faced reality. After some reflection (doing it a couple of times) I realized that my best workouts coincided with the days I was naturally more motivated and well-rested. The marijuana was just an innocent bystander in my quest for gains. Correlation, not causation, folks.


NOTE: The data is clear, marijuana decreases hand-eye coordination, produces slower reaction times, dis-enhances short term memory and increases appetite (munchies). These attributes are unhelpful for many sports and their associated training regimens.


Practical Application: Navigating Fitness Advice

Now that you’re armed with the knowledge of correlation vs. causation, let’s talk about applying this wisdom to your fitness routine. The next time you come across a sensational fitness claim, use your newfound skepticism to dissect the information. Ask yourself:


  • Is there a plausible mechanism that explains how one thing causes another?

  • Does the study control for other variables that could influence the results?

  • Are there similar studies that support the findings?


By asking these questions, you can better filter the noise and focus on what truly works. Remember, there’s no magic pill or secret hack. Effective fitness routines are built on consistency, effort, and scientifically sound principles.


In the ever-evolving world of fitness, it’s easy to get swept up by flashy headlines and too-good-to-be-true promises. But by understanding the difference between correlation and causation, you can make more informed decisions and avoid the pitfalls of pseudoscience. Stay curious, question everything, and always look for the evidence behind the claims. And if all else fails, just remember: Batman doesn’t cause crimes, and kale doesn’t control the weather. Happy training!

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