In this entry of the Athlete Development Journal, Dr. Zach Guiser helps you train your mind, build your body, and fuel your soul.

First, he tackles Training Your Mind by distinguishing between process and outcome. He explains that in a complex world, you can do the wrong thing and get a good outcome (or vice versa), but you shouldn't confuse luck with a good strategy . He warns against "history revisionism"—assuming that just because an athlete played year-round or did fancy footwork drills and succeeded, those methods were the cause of their success . Instead, he encourages athletes to think probabilistically: good processes enhance your odds, even if they don't guarantee results.

Next, he dives into Building Your Body by challenging the popular obsession with mobility. He argues that mobility is not a "more is always better" quality. While you need enough mobility to get into required positions, having passive flexibility that you cannot actively control can actually cause your injury risk to skyrocket. Finally, he Fuels Your Soul by breaking down the equation: Happiness = Reality - Expectations. He discusses the tension between chasing excellence (which requires high belief) and being happy. The solution? Keep insanely high expectations for the process (your daily habits) but release your expectations for the outcomes (things you cannot control, like scholarships).

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.

IN THIS EPISODE:

• 00:00 - Introduction
• 00:02 - Train Your Mind: Good Things Can Happen to "Bad" Processes
• 00:36 - The Danger of "History Revisionism" (The Susie, Johnny, & Kyle Examples)
• 01:13 - Thinking Probabilistically: Enhancing Odds vs. Guarantees
• 01:41 - Build Your Body: Knocking Mobility Off Its High Horse
• 02:08 - When Too Much Mobility Becomes Detrimental
• 02:45 - Fuel Your Soul: The Happiness Equation
• 03:22 - High Expectations for Process vs. Outcome

Here's the hypermobility article.

In this entry of the Athlete Development Journal, Dr. Zach Guiser helps you train your mind, build your body, and fuel your soul, specifically addressing the athlete who thinks they are "too busy" for in-season training.

First, he tackles Training Your Mind by reframing "busyness" not as a negative, but as a necessary stressor to build work capacity. He uses the analogy of a waitress in a small town versus a busy New York City restaurant to illustrate how high-volume work eventually becomes manageable through adaptation. He explains that students who stretch themselves in high school often thrive in college because they have built a higher capacity for work .

Next, he dives into Building Your Body by analyzing the dangers of stopping training during the season. He outlines three main benefits of continuing: staying healthier (carrying your "shield"), performing better in the playoffs, and achieving better long-term progress . He cites Patriots wide receiver Matthew Slater, noting that the team was squatting 80% of their maxes during Super Bowl week. Dr. Guiser describes a graph showing that stopping training is like taking "two steps forward and one step back," whereas continuous training leads to exponential compound growth . Finally, he Fuels Your Soul with a quote from economist Thomas Sowell: "There are no solutions, only trade-offs" . He encourages listeners to accept that every choice—whether chasing excellence or choosing family time—comes with a cost, and avoiding the "what ifs" is the ultimate goal.

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 .

IN THIS EPISODE:

• 00:00 - Introduction
• 00:46 - Train Your Mind: The Waitress Analogy & Building Work Capacity
• 02:51 - Build Your Body: Why In-Season Training prevents "One Step Back"
• 04:12 - The Matthew Slater Example: Squatting Heavy on Super Bowl Week
• 05:21 - The Graph: Visualizing Long-Term Progress vs. Stagnation
• 06:29 - How to Make It Work: Individualized, Tiered, and Flexible Training
• 08:12 - Fuel Your Soul: "There Are No Solutions, Only Trade-Offs"

In this episode, Zach Guiser and John Tropeano kick things off with Turkey Bowl preparations.

This leads to the main topic: a deep dive into Ashwagandha. Is it a miracle supplement for stress and gains, or does it just turn you into an "emotionless zombie"? Zach breaks down the three proposed physiological mechanisms:

1. HPA Axis Modulation: Reducing cortisol by calming the hypothalamus
2. GABA Agonist: Mimicking the brain's primary inhibitory neurotransmitter to induce calm.
3. Antioxidant/Anti-Inflammatory: Neutralizing free radicals and blocking NF-κB to stop inflammation cycles .

They review four major studies covering stress, anxiety, sleep, and physical performance. The results are surprisingly strong—showing significant reductions in stress and anxiety, and even large effect sizes for strength and cardiorespiratory fitness . However, Zach introduces the Attia Categories (Proven, Promising, Fuzzy, Noise, Nonsense) and places Ashwagandha firmly in the Promising category due to a lack of long-term human data.

Finally, they bust common myths: it doesn't work instantly (it takes weeks), "natural" doesn't always mean safe (poison ivy is natural, too), and more is not better (stick to ~600mg) .

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.

IN THIS EPISODE:

• 00:00 - Turkey Bowl Prep & The Greatest Cyclist You've Never Heard Of
• 06:38 - Main Topic: Should Anyone Be Taking Ashwagandha?
• 07:47 - The Public Narrative: Emotional Zombies & Testosterone Myths
• 11:25 - How Ashwagandha Works: The 3 Mechanisms (HPA Axis, GABA, Inflammation)
• 22:15 - Study #1: Effects on Stress (Big Reduction, High Heterogeneity)
• 35:48 - Study #2: Effects on Anxiety (Massive Effect Size)
• 42:26 - Study #3: Effects on Sleep (0.59 Effect Size)
• 44:03 - Study #4: Effects on Physical Performance (Strength, Power, VO2 Max)
• 50:00 - Summary: What Actually Matters (Stress, Anxiety, & Safety)
• 52:54 - Zach's Final Stance: Should You Take It?
• 57:04 - The Attia Categories: Proven, Promising, Fuzzy, Noise, Nonsense
• 1:00:38 - Mythbusters: Instant Results, "Natural = Safe," & Emotional Blunting

In this entry of the Athlete Development Journal, Dr. Zach Guiser helps you train your mind, build your body, and fuel your soul.

First, he tackles Training Your Mind by arguing that robust athletic development from ages 0–18 is more valuable than a massive trust fund. He explains the concept of the "Don't Screw It Up Years" (starting around age 25) and why building a strong physical base early in life makes it infinitely easier to maintain health later on, thanks to muscle memory and nuclei retention .

Next, he dives into Building Your Body by exposing a common lie in physical therapy: the 90% Limb Symmetry Index (LSI). He breaks down why aiming for 90% of your non-injured leg is often a trap—especially if your "healthy" leg has gotten weaker during recovery . He explains why you must aim to be stronger than your pre-injury self, not just symmetrical to a de-conditioned limb .

Finally, he Fuels Your Soul with a perspective on duality: you cannot truly know joy, light, or energy without first experiencing despair, darkness, and exhaustion .

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.

IN THIS EPISODE:

• • 00:00 - Introduction

  • 00:18 - Train Your Mind: Why Athlete Development is Worth More Than a Trust Fund

  • 02:06 - The "Don't Screw It Up Years" (Age 25+)

  • 03:07 - Build Your Body: The Lie Your Physical Therapist Is Telling You (The 90% Barrier)

  • 03:28 - What is the Limb Symmetry Index (LSI)?

  • 04:26 - Why 90% of a Weak Leg is "A Smiling Pile of Poop"

  • 05:42 - Fuel Your Soul: Why You Can't Know Joy Without Despair

In this episode, Zach Guiser and John Tropeano kick things off with John's full recap of his first Ironman, battling the wind, and his caffeine strategy for the 13+ hour race .

This leads to the main topic: a deep dive into whether teenage athletes should consume caffeine. Zach breaks down the science, explaining that caffeine doesn't create energy (ATP) but rather blocks the brain's sleep-pressure signals (adenosine) to make you feel less tired .

They review two major studies:

1. Safety: For adolescents, the data is limited, but the available evidence suggests a limit of around 1.13 mg per pound of body weight per day (2.5 mg/kg) .

   
   

2. Efficacy: An umbrella review of 21 meta-analyses found that while caffeine does improve performance, the effect size is very small for most explosive, power-based sports . Its most significant impact is on aerobic endurance.

   
   

Finally, they bust three common myths:

• Caffeine does not stunt your growth.

• It does not dehydrate you at normal doses .

• It does not provide a major boost for short-term, high-intensity sports.

  
  

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.

IN THIS EPISODE:

• 00:32 - John's Ironman Recap

• 03:38 - John's Caffeine Intake for the Ironman (350mg)

• 04:52 - Main Topic: Should a Teenage Athlete Consume Caffeine?

• 05:17 - The Public Narrative on Caffeine (Energy Drinks, Pre-Workout, etc.)

• 13:03 - What the Science Says: What is Energy (ATP)?

• 16:14 - How Caffeine Actually Works (It Blocks Adenosine)

• 18:06 - Study #1 (Wachoff et al.): Is Caffeine Safe for Teens?

• 20:19 - Study #1 Findings: Suggested safe limit is 1.13mg/lb (2.5mg/kg)

• 22:23 - Study #2 (Grgic et al.): Is Caffeine Effective for Performance?

• 24:57 - The Catch: Statistical Significance vs. Small Effect Size

• 33:59 - Zach's Final Stance on Caffeine for Teens

• 34:32 - Mythbusters Start

• 34:48 - Myth #1: Does Coffee Stunt Your Growth?

• 38:45 - Myth #2: Does Caffeine Dehydrate You?

• 41:00 - Myth #3: Do Energy Drinks Make You Perform Better?

In this entry of the Athlete Development Journal, Dr. Zach Guiser tackles Training Your Mind by sounding the alarm on a growing public health issue: the rise of sports betting among young athletes. He discusses the "illusion of control" that makes athletes particularly vulnerable and why this is a danger hiding in plain sight.

Next, he dives into Building Your Body with a deep exploration of dynamic balance. He explains why this is a key separator for great athletes and breaks down the three essential balance receptor systems—Visual, Proprioceptive, and Vestibular. He details how the inner ear (semicircular canals and otolith organs) senses rotation and movement , and why these complex systems are highly trainable.

Finally, he Fuels Your Soul with a simple, powerful framework from James Clear: spend time on one thing for the future and one thing for the present.

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.

IN THIS EPISODE:

• 00:00 - Introduction

• 00:19 - Train Your Mind: The Hidden Danger of Sports Betting

• 02:07 - Build Your Body: The 3 Systems of Dynamic Balance

• 06:44 - Fuel Your Soul: A Simple Framework for a Fulfilling Day

In this episode, Zach Guiser and John Tropeano kick things off with John's taper anxiety for his upcoming Ironman before diving into the wild NBA betting scandal involving Terry Rozier, Chauncey Billups, and a secret poker ring with characters like "Albanian Bruce".

This leads to the main topic: a deep dive into supplements. Zach lays down the single most important rule—the FDA does not regulate supplements —and explains why athletes must look for third-party testing labels like NSF Certified for Sport or Informed Sport to avoid banned substances.

From there, they focus on creatine, breaking down:

• How it works for explosive energy (the phosphocreatine system) .

• If it works (Yes, for power/strength, but the effect size is small).

• The myths vs. facts on kidney safety (creatinine vs. cystatin C) and hair loss.

• The big question: Should adolescents take it? They review the limited research and land on the ISSN's stance: it's only for mature athletes who have already mastered their diet, sleep, and training .

• What to buy: Stick to basic creatine monohydrate and avoid ineffective gummies.

  
  

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.

IN THIS EPISODE:

• 01:15 - The NBA Betting Scandal Explained (Rozier, Billups, Albanian Bruce)

• 07:35 - Main Topic: Supplements in High School & College Locker Rooms

• 10:10 - The Most Important Rule: The FDA Does Not Regulate Supplements

• 12:55 - What to Look For: NSF Certified for Sport & Informed Sport

• 14:45 - What is Creatine and How Does it Work? (The Phosphocreatine System)

• 17:51 - How to Read Research: A Guide to Scientific Studies

• 22:25 - Does Creatine Actually Work? (The Adult Research)

• 28:29 - The "Effect Size" vs. Statistical Significance

• 31:00 - Creatine Safety: The Kidney Myth (Creatinine vs. Cystatin C)

• 32:21 - Creatine Safety: The Hair Loss Myth

• 35:51 - The Real Question: Should Adolescents Take Creatine?

• 41:34 - What Form of Creatine is Best? (Avoid Gummies)

In this entry of the Athlete Development Journal, Dr. Zach Guiser provides a framework for training your mind, building your body, and fueling your soul.

First, he tackles Training Your Mind by exploring the concept of "High Agency" and asking whether you are someone who happens to the world, or if you let the world happen to you .

Next, he dives into Building Your Body with a comprehensive answer to one of the most common questions: "Should I take this supplement?". After laying down three crucial caveats—including the non-negotiable importance of NSF Certified for Sport products —he breaks down the most popular supplements into three clear categories:

• Ones almost everyone should take: Creatine , Protein Powder , and Vitamin D.
• Ones helpful in specific situations: Caffeine , Multivitamins , Omega-3s , Collagen , Magnesium , and Iron.
• Ones that are a waste of money or dangerous: Pre-workout , individual amino acids (BCAAs/EAAs) , and Green Superfoods.

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.

Links:

- read this article: gtperformance.co/adj102825

- the phenomenal high agency essay: highagency.com

- subscribe to the newsletter: gtperformance.co/newsletter

- creatine article: gtperformance.co/creatine/

IN THIS EPISODE:

• 00:00 - Introduction

• 00:27 - Train Your Mind: Are You a High Agency Person?

• 00:54 - Build Your Body: A Breakdown of Supplements

• 01:23 - The 3 Most Important Rules for Taking Supplements

• 02:44 - Category 1: Supplements Almost Everyone Should Take

• 04:36 - Category 2: Supplements for Specific Situations

• 07:59 - Category 3: Supplements That Are a Waste of Money

• 10:04 - Fuel Your Soul: The 5-4-3-2-1 Trick for a Busy Brain

In this episode, Zach Guiser and John Tropeano kick things off with a discussion about the staggering physical and mental excellence of Taylor Swift's 149-show Eras Tour.

They then pivot to a new, in-depth format, tackling one major question: Are artificial turf fields more dangerous than natural grass?

Zach breaks down the scientific literature, explaining the difference between minor injuries and the catastrophic, season-ending injuries (like ACL tears) that are more common on turf. He explores the "Traction Theory"—how the high friction that improves performance is the same thing that increases risk. The conversation also covers the major exceptions, like lower concussion rates on turf , the financial incentives for teams, and the ultimate trade-off athletes make between performance and health.

IN THIS EPISODE:

• 01:21 - The Unbelievable Physical Feat of Taylor Swift's Eras Tour

• 04:34 - Main Question: Are Artificial Turf Fields More Dangerous Than Grass?

• 05:51 - Analyzing the Research: Do More Injuries Actually Happen on Turf?

• 08:31 - Bias in Research (The Turf Industry Funding)

• 09:09 - The Key Difference: Catastrophic vs. Minor Injuries

• 12:21 - The "Traction Theory": Why Turf Causes More ACL Injuries

• 13:21 - The Performance vs. Safety Trade-Off

• 17:42 - The Financial Reason for Turf (Cost vs. Maintenance)

• 19:47 - The Big Exception: Concussion Risk is Lower on Turf

• 22:03 - Final Summary: Turf, Traction, and Trade-Offs

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.

In this entry of the Athlete Development Journal, Dr. Zach Guiser helps you avoid 95% of injuries with reverse engineering.

First, he tackles the topic of Training Your Mind by exploring how to find meaning in suffering, drawing on a powerful quote from Viktor Frankl.

Next, he dives deep into Building Your Body with Part 2 of "How to Avoid 95% of Injuries". This week, he reverse-engineers the sport of basketball. He walks you through his exact research process—using AI, PubMed, and academic journals—to find the peak demands of the sport. He then provides the concrete numbers for peak jumps, high-intensity change of direction reps, and running distance. Using these numbers, he lays out a 7-week, 10% progression plan to safely build your load capacity and provides a practical method for tracking your load during open gyms.

Finally, he Fuels Your Soul with a quote from George Bernard Shaw, making the case that all progress depends on being "unreasonable" in your pursuit of excellence .

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.

IN THIS EPISODE:

• 00:00 - Introduction

• 00:54 - Train Your Mind: Finding Meaning in Your Suffering

• 02:20 - Build Your Body: How to Avoid 95% of Injuries (Part 2: Basketball)

• 02:51 - The Research Process: How to Find Peak Demands for Your Sport

• 06:46 - Peak Demands for Basketball (The Numbers for Jumps, Sprints, & COD)

• 10:07 - A 7-Week Progression Plan to Prevent Injuries

• 10:48 - How to Track Your Load and Stats in Open Gyms

• 14:13 - Fuel Your Soul: Be Unreasonable

Read this article at gtperformance.co/adj102125.