Physiology Friday Top 10 Posts of 2025

Zone 2 training, low-carb endurance, caffeine for fat burning, and more!

Greetings, and Happy Holidays!

I hope you’re having a fulfilling week and spending some quality time with friends and family (and some time alone too).

As the year comes to a close, I wanted to share the most popular posts from the Physiology Friday newsletter in 2025. Maybe you’ve already read one or more of them, maybe you missed one, or maybe you’re a brand-new subscriber (welcome!)

Either way, enjoy (re)reading them—perhaps there are some practical strategies or surprising science you missed the first time around!

#1—Everything You Need to Know about Zone 2 Training

Physiology Friday #262: Everything You Need to Know about Zone 2 Training

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#2—Is Glycogen Really That Important for Endurance Performance?

Physiology Friday #253: Low-carb Matches High-carb for Performance: Is it Time to Question the Obligatory Role of Glycogen for Endurance Exercise?

#3—Low-Carb vs. High-Carb Fueling for Health and Performance

Physiology Friday #254: Fueling for Performance and Health: Lessons from a Recent Low-Carb vs. High-Carb Study in Athletes

#4—Caffeine Improves Performance and Fat Burning during Fasting

Physiology Friday #256: Caffeine Boosts Performance & Fat Burning during Carb-Restricted Training

#5—Activity Breaks Maximize HIIT’s Benefits

Physiology Friday #261: Combining High-intensity Training with Frequent Activity Breaks Maximizes Cardiovascular Benefits

#6—Strength Training for Endurance, HIIT Protocols, and Omega-3s

Physiology Friday #255: Strength Training for Endurance, Optimal HIIT Protocols, Omega-3s + a Big Announcement!

#7—What Limits VO2 Max?

Physiology Friday #266: A New Theory on What Limits Our Maximal Aerobic Capacity

#8—How to Train Your Physiological Resilience

Physiology Friday #260: How to Train Your Physiological Resilience

#9—Strength and Endurance Training Change the Heart Differently in Men and Women

Physiology Friday #258: How Strength and Endurance Training Shape the Heart Differently in Men vs. Women

#10—Fasting and Exercise Performance

Physiology Friday #252: How a Week-long Fast Affects Performance and Metabolism During Exercise