🥇 The Athlete Development Journal

Developing speed, strength, power, health, and character, so your athlete gets the most out of their athletic career.

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“Should an adolescent athlete consume caffeine?”

Caffeine.

Good, bad?

Useful, useless?

Safe, harmful?

Let’s find out.

What’s everyone saying?

The public narrative, especially among high school athletes, is that caffeine is somewhat of a legal performance enhancer.

Need an “extra boost” to combat the fatigue from school, homework, clubs, sports, drama, etc.?

Get some caffeine.

It’s incredibly easy to access. There coffee shops on every corner and energy drinks in every gas station.

The main players doling out caffeine are:

• Coffee: Relatively popular, but not as much with teenagers as adults. (Side note, Dunkin’ or Starbucks?)
• Energy Drinks:
  • Classic Drinks: Red Bull and Monster are the traditional big two.
  • Newer Drinks: C4, Ghost, and Rain are increasingly popular, often coming in aggressive cans with 200-350 mg of caffeine.
  • Different Target Drinks: Celsius and Alani are very popular, especially with younger athletes and high school girls, using “pretty designs” to seem less intense.
• Pre-workout: Popular with teenage boys in late high school.

What does the science say?

Now, forget about what the public says. What does the science say? Is caffeine safe and effective for a teenage athlete?

Before we get into that, we need to establish some background knowledge.

The background part 1: What is energy?

If the goal of caffeine is to give you more energy, then we need to have a quick overview of what energy even means in the human body.

Energy (en·er·gy): the capacity to do work or produce change, powering all life processes.

• If you want to contract a muscle, you need energy,
• If you want to send a nerve signal, you need energy.
• If you want to build hormones, you need energy.
• If you want to pump blood, you need energy.
• If you want to breathe, you need energy.

Clearly, energy is important. But, where does this energy come from?

I don’t want this to turn into a boring bio lecture, so I’m going to try to keep it straight to the point.

You eat food, which is made up of macronutrients (carbs, proteins, and fats).

Those macronutrients are digested into their basic building blocks (glucose for carbs, amino acids for proteins, and triglycerides for fats) and absorbed into the body.

The body then goes through fancy processes (glycolysis, the Krebs Cycle, and the Electron Transport Chain) to break down those building blocks even further. As they’re broken down, they kick out something called adenosine triphosphate, more commonly known as ATP.

ATP is the magic substance here. ATP is the energy currency in your body.

In order to do anything at all that requires energy, you need to donate some ATP.

Essentially your body says,

“Oh, you want to contract that muscle? Give me some ATP.

You want to make that hormone? Give me some ATP.

You want your brain to think? Give me some ATP.”

But, here’s the thing. Consuming caffeine doesn’t result in ATP being produced.

The background part 2: So, how does caffeine fit into all of this?

How in the world can something “give you energy” if it doesn’t produce ATP?

Well, first we need to keep playing out the ATP process.

After ATP is used, it gets broken down, eventually some of it ends up as free adenosine (remember, it was adenosine triphosphate, so eventually the 3 phosphates are all stripped away).

There are specific adenosine receptors in your brain. These adenosine receptors are specially shaped to fit adenosine in there.

When adenosine binds to those receptors, it builds sleep pressure. Or, more simply, it makes you tired.

That makes sense, right? If ATP is used for energy, having a build up of broken down adenosine from ATP is a good signal that “Man, we’ve used a lot of energy today. We need some rest.”

Caffeine, however, is shaped just like adenosine. Caffeine fits into the adenosine receptors. When caffeine lodges itself into the adenosine receptor, adenosine can’t fit in and it can’t start signaling to build sleep pressure

So, caffeine doesn’t actually give you more energy from the true definition. It just makes you less sleepy.

That’s cool and all, but is caffeine safe and effective for an adolescent athlete?

Let’s dive into our first study:

1) Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children (by Wikoff and others).

• “Can I trust the results?”
  • Yes, but with limitations.
    • Pros: systematic review, rigorous methodology, peer reviewed, they screened >5,000 studies, most of the available studies were rated high quality (low risk of bias, consistent findings, specific to population)
    • Cons: very limited data on adolescents (10 studies looked at blood pressure, 6 looked at heart rate, 2 looked at mood, 3 looked at headache, 3 looked at sleep).
• “What did the study find?”
  • For risk of fracture, bone density, blood pressure, heart rate, mood, headache, and sleep, healthy adults having an intake of 400 mg of caffeine per day is not associated with negative outcomes.
  • For those same outcomes, no definitive conclusions were able to be drawn for adolescents. There was simply not enough data. However, the authors state “the available evidence suggests that 2.5 mg caffeine/kg body weight per day remains an appropriate recommendation.” (That’s 1.13 mg per pound of bodyweight for us ‘merican folks. So, if you weigh 150 lbs, it’s postulated to be safe to consume 169.5 mg of caffeine per day.)
• “Can I use these results in my context?”
  • Yes, the studies are specific to adolescence.

And to address performance, let’s look at our next study:

2) Wake up and smell the coffee: caffeine supplementation and exercise performance—an umbrella review of 21 published meta-analyses (by Grgic and his team)

• “Can I trust the results?”
  • Yes.
    • Pros: umbrella review (which is a systematic review of systematic reviews), rigorous methodology, peer reviewed, included a total of 320 individual studies and 4,855 total participants.
• “What did the study find?”
  • For healthy adults as a whole, caffeine had a significant positive effect on:
    • aerobic endurance,
    • muscle strength,
    • muscle endurance,
    • anaerobic power,
    • vertical jump height,
    • exercise speed,
    • and short-term high-intensity exercise.
  • However, for all of the performance metrics, the effect size was small (roughly 0.20). The only exception was some studies showed a medium to high effect size for aerobic endurance (a little over 0.50).
• “Can I use these results in my context?”
  • Ehhh… I couldn’t find quality research on kids. This umbrella review is all about adults. Furthermore, it’s on all healthy adults, not specific to athletes.

What’s actually important here?

1. Caffeine is probably safe for adolescents who are near physical maturity, but they should stay around 1.13 mg/lbs of bodyweight per day.
   • As a side note, a single energy drink or scoop of pre-workout likely has 200 mg or more of caffeine in it, so for many of you average-sized or smaller individuals, that alone exceeds your daily dose.
2. Caffeine improves performance in most physical domains, but only slightly. The one area it likely has a meaningful effect on is endurance tasks.
   • This hasn’t been demonstrated in adolescents, but it’s logical to extrapolate the adult data to someone near physical maturity.
3. Regular use of caffeine will result in developing tolerance, meaning it takes more for you to feel the same effects.
4. Caffeine makes you less sleepy, which impacts your sleep quality if taken too late in the afternoon.

My stance: “Should an adolescent athlete consume caffeine?”

If an athlete:

• is near physical maturity,
• takes less than 1.13 mg/lbs of bodyweight in a day,
• and takes it 3 days per week or less before meaningful performances,

then yes.

Other than that, the effect size is too insignificant to warrant any risk.

Myth busters

Myth #1: “Coffee stunts your growth.”

• The Verdict: False.
• The Origin: This myth appears to have originated from a marketing ploy in the late 19th or early 20th century.
• A coffee alternative called “Postom” ran ad campaigns to “smear and slander the coffee industry”.
• They paid for studies and ran ads with headlines like, “Coffee cuts down weight and height of children. Figures show,” to create a problem that their product could “solve”.

Myth #2: “Caffeine dehydrates you.”

• The Verdict: Mostly false.
• The Origin: Very early studies did show caffeine was a diuretic, but they used “absurdly high doses”.
• Modern data, looking at more reasonable doses (like the 400 mg/day limit for adults), shows the diuretic effect size is “so small” that it doesn’t meaningfully impact your overall hydration levels.
• As long as you aren’t taking 1,000+ mg a day, you should be fine

Myth #3: “An energy drink will make me perform better on game day.”

• The Verdict: Unlikely, for most sports.
• The Reality: As the science section showed, the performance-enhancing effect of caffeine is very small for short-duration, high-intensity, or explosive activities.
• The main benefit comes when you are already fatigued, which is why it has a larger effect on endurance tasks.

Let’s wrap it up with a couple important things…

1. This newsletter and podcast is completely free. I spend many hours each week researching, writing, illustrating, recording, editing, and uploading. The best way you can support it and allow it to continue is to share it with people you know. You can just send them to ​gtperformance.co/newsletter​ and they can subscribe there!
2. Everything in these newsletters, podcasts, social media, and on our website is for educational purposes only and should not be taken as medical advice for you or your athlete. Consult directly with a healthcare professional.

Thanks so much for your help in spreading the word about athlete development!

Be >,

Zach

Dr. Zach Guiser, PT, DPT, CSCS