Physiology Friday #271: Is Durability the Most Underrated Trait in Endurance Performance?

Your VO₂ max changes after a few hours of exercise. Here's what it means for training and racing.

Greetings!

Welcome to the Physiology Friday newsletter.

This week I want to shoutout my new favorite protein bar—BOLD Bar. Founded by Sean Jagermann, BOLD BAR launched in April 2025 to redefine on-the-go fuel. Each bar packs 20g of protein and 100mg of caffeine, and is sweetened only with honey, for a clean, simple, and satiating snack. BOLD is the only b…