Zone 2: The Aerobic Engine and Workhorse

Zone 2: The Engine Room of Endurance

Zone 2 is the superstar of endurance training — the zone that builds your long-distance engine, transforms your metabolism, and gives you the durability needed for triathlon racing. It may not feel heroic, but it delivers the biggest long-term return.

Why Zone 2 Works So Well

You improve how your body uses oxygen

Your aerobic system becomes more efficient, meaning you can sustain faster speeds at lower effort.

You burn more fat as fuel

Zone 2 teaches your body to rely on fat instead of carbohydrates. This is massive for long-course triathlon, where glycogen is limited.

Your mitochondria grow and multiply

Think of mitochondria as your muscles’ power plants. More of them = better endurance.

You produce less lactate at steady effort

This means you can stay aerobic for longer before drifting into that uncomfortable zone.

You increase slow-twitch fibre strength

These fibres do the heavy lifting on long bikes and long runs. Zone 2 strengthens them without wearing them out.

What Zone 2 Feels Like

• Strong but comfortable

• Full sentences still possible

• Breathing steady, not strained

• You could hold the pace for hours

This is the “all-day pace” that fuels triathlon success.

Simple Zone 2 Session

60 minutes steady aerobic ride or runStay smooth and controlled, no drifting into tempo.

Zone 2 is where endurance lives. Build it well.

Tip: Stay controlled. If you can talk freely without pausing for breath, you’re in the right spot.

Short Session:

• 45–75 min steady aerobic

• Hold a smooth, controlled effort start to finish