1/7
How many carbs per hour during cycling races?
In recent years, intake has increased massively:
30 → 60 → 90 → 120 g/h… and even more.

But should everyone aim for the same number?
🧵👇 2/7
Peak exogenous glucose oxidation varies A LOT between individuals.
👉 ~30 to ~70 g/h
👉Some athletes even reach ~90 g/h
So what explains these differences?

1/10
Zone 2 is everywhere.
Before we talk about benefits or methods, we need to answer a simple question:
👉 What exactly is Zone 2 training intensity? 2/10
A recent expert consensus (14 applied sport scientists + pro coaches) defines Zone 2 as:
👉 Low-intensity endurance training just below the 1st exercise threshold
🎯 Goal:
Elicit a steady-state response
With minimal metabolic disturbance

1/10
In 2026, what is the gold standard for the 2nd exercise threshold?

There are many concepts used in endurance physiology:
• MLSS
• LT2
• Critical Power
• FTP

They all try to describe the same boundary - but they are not the same thing. 🧵👇 2/10
The 2nd exercise threshold represents the Maximum Metabolic Steady State (MMSS).

It is the highest intensity where metabolic steady state can still be maintained.

Above this point:
• VO₂ keeps rising
• intramuscular metabolites (Pi, K+.H+) accumulate until a critical point
• fatigue develops rapidly

This is the boundary between heavy/medium and severe/high exercise domains.