The Basics of Zone 3 Training for Hybrid Athletes

Ever heard someone say “Zone 3 is a waste of time”?

Or it's a "gray zone?"

They’ll tell you it’s too hard to recover from and not hard enough to improve performance.

 But like most things in training, it’s not that simple, especially for hybrid athletes.

When used strategically, Zone 3 training can be a powerful tool to improve muscular endurance, increase lactate tolerance, and bridge the gap between easy efforts and race pace.

Here's why: 

What Is Zone 3 Training?

Zone 3 is the “middle gear” of endurance training.

It’s harder than a conversational Zone 2 effort but nearly as intense (or as hard to recover from) as threshold work (Zone 4).

Think of it as a moderately hard effort, something you could fairly comfortably sustain for about an hour, but could go longer if needed.

Zone 3 is typically "marathon pace" for most people.

Depending on how you measure it, Zone 3 typically sits at:

• 78–88% of max heart rate

• An RPE (Rate of Perceived Exertion) of 5–6/10

It’s often called the "gray zone" because it’s neither truly aerobic nor fully anaerobic.

But for hybrid athletes, it’s more than just a no-man’s-land.

And for Hyrox athletes, high Z3/low Z4 is where you should be spending most of your time in on race day.

Why Zone 3 Is Useful for Hybrid Athletes

Most hybrid events, like Hyrox, CrossFit-style metcons, and functional fitness races, demand sustained output at a moderately high intensity.

You're not cruising in Zone 2, but you're not redlining either.

You’re working hard, grinding, pushing, but not blowing up.

That’s high Zone 3, low Zone 4 for most.

Here’s what smart Zone 3 training can do:

• Build muscular endurance for long efforts under fatigue

• Improve tempo running and race pace stamina

• Train your body to buffer lactate and delay fatigue

• Boost cardiovascular efficiency under moderate strain

In short, Zone 3 helps you go harder for longer without falling apart.

It’s also a key training piece for those looking to improve long-distance pacing without high-mileage weeks, like I did in How I Turned My 5K Pace Into My Half Marathon Pace In 6 Months… By Only Running 1–2 Days Per Week.

When and How to Use It

Zone 3 shouldn’t make up the bulk of your training, but sprinkling it in can offer big returns.

It's most useful when training for a longer event like Hyrox, a half marathon, or longer.

It's not as helpful if you were training for something like a max deadlift and a 1-mile race.

Try these approaches:

1. Steady-State Zone 3 Efforts

• 20–40 minutes at a sustained Zone 3 pace

• Great for improving race pace efficiency

• Example:

  • 10-15 mins easy, 20-30 min Zone 3, 10-15 mins easy

2. Long Intervals

• 3x2 miles with short rest or easy jog between

• Easier to manage mentally and recover from

• Example: 4x6 minutes in Zone 3, 60s rest between

3. Race Simulation Workouts

• Combine Zone 3 running with functional movements

• Mimics real competition pacing

• Example: 800m Zone 3 run + 50 wall balls, repeat x3

Don’t overdo it, too much Zone 3 can eat into recovery and blunt adaptation from higher-quality sessions.

But implemented smartly, it can greatly improve your fitness.

The Bottom Line

Zone 3 training isn’t junk mileage, it’s the bridge between your easy base work and your max efforts.

For hybrid athletes, it’s a critical pace zone that can show up on race day, so you better train for it.

Today’s Action Step:

Add a Zone 3 session this week, either a tempo run, a long grinder workout, or a race simulation, and note how your body responds.

The more familiar you are with this zone, the more dialed in you’ll be when it counts.

This is exactly what I help clients do with my 1-on-1 coaching, so you stop guessing, stop spinning your wheels, and start getting real results.

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