William A. Wallace, Ph.D. (@WilliamWallace)

How endurance training intensity is measured This chart organizes the main ways coaches and scientists define exercise intensity, linking lactate thresholds, perceived exertion, heart rate, and energy use into one framework. It shows how endurance training zones correspond to both physiological and...

How your body moves electrons from food to energy This figure explains how the human body acts like an electrical circuit—moving electrons extracted from food all the way to oxygen to generate energy. Every meal you eat feeds an invisible current that powers your cells through a continuous flow of ...

Creatine made simple: how your body builds and uses its energy buffer Creatine is a molecule your body makes naturally to keep energy flowing smoothly, especially in muscles and the brain. Here’s how the system works: 1️⃣ Where It Begins Creatine starts in your kidneys, where the amino acids argi...

How magnesium balance goes wrong Magnesium is a key electrolyte for nerve signaling, muscle contraction, and heart rhythm. Because it regulates over 300 enzymatic reactions, both low and high magnesium levels can disrupt nearly every system in the body. This diagram shows how magnesium metabolism b...

🔋 Mitochondria run their core power system using bacterial-style DNA. 🧬 But they need your nuclear DNA for support, repair, and growth. Think of it like a battery with its own mini-engine; it sparks on its own, but the car (your cell) builds and maintains it. Mitochondria are semi-independent, po...

Your muscles do more than move you; they communicate. Here’s how this muscle–brain conversation works 1️⃣ Muscles Release Myokines When You Move Every time you contract a muscle — whether walking, lifting, or cycling — your body releases myokines into the bloodstream. These molecules travel to t...

Your immune system doesn't only defend, it remembers This diagram maps how the body’s innate and adaptive immune systems work together to identify, attack, and remember pathogens. It shows how different immune cells, antibodies, and signaling molecules coordinate to protect against infection while ...

Chemistry writes the story of life. Every cell, every second, it tells it again - powered by molecular design. At the core of this process lies the citric acid cycle, the central hub of metabolism. Here, acetyl-CoA derived from carbohydrates, fats, or proteins enters a precise series of reactions t...

Creatine made simple: how your body builds and uses its energy buffer Creatine is a molecule your body makes naturally to keep energy flowing smoothly, especially in muscles and the brain. Here’s how the system works: 1️⃣ Where It Begins Creatine starts in your kidneys, where the amino acids argi...