A BOOK BY HÜSEYIN AKBULUT

THRESHOLD

On Fatigue, Endurance, and the Limits of the Body

The science of why your body quits before your mind does.

The Turkish edition (EŞİK) is available now. English edition in preparation.

For Endurance Athletes

Understand the physiology behind your training. Learn why lactate isn’t your enemy, what your VO₂ max really means, and how to train at the right intensity.

For Coaches

Evidence-based periodization, polarized training science, and 275 references you can cite. Build programs grounded in research, not tradition.

For Science Students

A comprehensive reference spanning exercise physiology, evolutionary biology, sport nutrition, and fatigue science. 22 chapters, each with its own bibliography.

What’s Inside

Written by a sport scientist. Backed by research. Readable by anyone.

✦ Lactate shuttle — why the “poison” is actually fuel

✦ VO₂ max, threshold, economy — the three pillars of endurance

✦ Central governor — your brain limits you before your body fails

✦ Born to run — 2 million years of evolutionary design

✦ Persistence hunting — the oldest strategy on earth

✦ Polarized training — why elites run slow 80% of the time

✦ Sleep & recovery — half of training happens in bed

✦ Altitude & heat — environmental extremes

✦ Sport nutrition — 2:1 formula, caffeine, carb periodization

✦ Culture — Tarahumara, Kenya, Kırkpınar, ekiden

Read Before You Buy

Three chapters available as free excerpts:

Chapter 12
Born to Run: The Evolution of Endurance

Chapter 14
Sled Dogs and the Pronghorn Paradox

Chapter 13
Culture as a Training Program

About the Author

Hüseyin Akbulut, MSc — Sport Scientist, Marmara University

“I wrote THRESHOLD after spending a decade studying why humans push past pain — in labs, on rowing machines, and at the edge of what physiology says is possible. This book is my attempt to connect 275 pieces of research into one coherent story about human endurance.”

Full bio →