5K Training: What Is Zone 4 / Threshold?
SUMMARY:
Zone 4, around 87–93% of max heart rate, RPE 7–8, represents threshold running. It sits just below your all-out effort and teaches you how to hold high-intensity pace with control. For 5K runners, Zone 4 training develops lactate tolerance, boosts race-specific stamina and sharpens mental resilience. In this guide, you'll learn how to train at threshold, when to use it and how to make it a key part of your race preparation.
Build Your Edge with Threshold Training
Speed alone won’t carry you through a 5K, control matters just as much. That’s where Zone 4 training comes in. It builds your ability to hold a hard pace without tipping over the edge. It helps you resist fatigue, stay mentally focused and maintain form when your legs and lungs are screaming. Zone 4 sits between endurance and speed. It’s the race-prep zone, sharpening your ability to manage intensity under pressure. For 5K runners, it’s where real performance is forged.
What Is Zone 4 Running?
Zone 4 is your threshold zone, high effort, high reward. It’s the hardest zone you can sustain for an extended period without tipping into full anaerobic effort.
Zone 4 Defined:
Heart Rate: 87–93% of Max HR
Effort Level: 7–8 out of 10
Breathing: Heavy, focused, can only speak in short phrases
Pace: Close to your 5K race pace, just under maximum
Threshold effort is challenging but controlled. You’re aware of the strain, but you can manage it. It’s not all-out, but you’re definitely working hard.
Why Zone 4 Matters in 5K Training
Threshold training gives you the ability to handle race pace without fading. It improves your body’s ability to process lactate, increases your stamina at higher intensities and sharpens your mental control when running gets uncomfortable.
It’s one of the final tools in a smart 5K build. Used after your endurance is established and your tempo work is consistent.
Top Benefits of Zone 4 Running:
Builds Lactate Tolerance
Trains your body to manage and clear lactate more efficiently, delaying fatigue.Develops Mental Toughness
Helps you stay calm under pressure and resist the urge to back off.Sharpens Race Pacing
Prepares you to dial into your 5K pace without going too hard or too easy.Improves VO2 Utilisation
Increases the amount of oxygen your body can process at high intensity.Extends Speed Endurance
Allows you to run hard for longer, essential in the final kilometre of a 5K.
How to Use Zone 4 in a 5K Plan
Zone 4 training isn’t about volume. It’s about quality. Most runners benefit from just one well-placed Zone 4 session per week in the final few weeks before racing.
The goal is to simulate race demands without tipping into full-blown VO2 Max work. Use it to fine-tune your pacing, test your mental strength and prepare your body for the exact intensity of race day.
When to Train in Zone 4:
Race Prep Block: Final 4–6 weeks before goal race
After Base Phase: When aerobic foundation is already solid
Tired but Not Fatigued: When you can bring focus without risking injury
Sample Uses in a 5K Week:
Option 1: Threshold Intervals
4 x 5 minutes @ Zone 4, with 90 sec jog recovery
Teaches sustained effort, pacing and mental control
Option 2: Broken Tempo Run
3 x 8 minutes @ Zone 4, with 2 min easy jogs
Builds lactate buffering capacity without overload
Option 3: Threshold Finishers
10 minutes @ Zone 4 after 40 min Zone 2
Simulates final push of a 5K when legs are already tired
Option 4: Cruise Repeats
5 x 1K @ threshold pace, 75 sec jog recoveries
Great for sharpening race pace and managing effort under pressure
You only need one of these per week. Keep it controlled and purposeful.
How Do You Know You’re in Zone 4?
You’re working hard, but not breaking. You’re focused, but not panicking. That’s Zone 4.
How to stay in the right range:
Heart Rate: 87–93% of max
Talk Test: Short phrases only—speech feels cut off
Effort: 7–8 out of 10—uncomfortable but steady
It should feel like a high-performance effort you can sustain for 20–40 minutes, but not much longer.
Common Mistakes with Zone 4 Training
Zone 4 gives big rewards, but only when used wisely.
Pushing into Zone 5: This turns threshold into anaerobic work, raising recovery cost and reducing quality.
Too Many Sessions: Threshold work is hard. If you’re doing it 3+ times a week, you’re overcooking it.
No Warm-Up or Cool-Down: Start every Zone 4 day with 10–15 minutes of Zone 1 running. End the same way.
Doing It Too Early: Zone 4 only works if your endurance is already in place. Rushing it leads to burnout.
Zone 4 vs Other Training Zones
Every zone has a role. Zone 4 is your sharpening tool.
Zone 1 / Recovery (68–73%)
Effort: Very easy
Use: Recovery, warm-up, cooldown
Check out: Running: What Is Zone 1 / Recovery?
Zone 2 / Endurance (73–80%)
Effort: Easy and steady
Use: Base building, aerobic development
Check out: Running: What Is Zone 2 / Endurance?
Zone 3 / Tempo (80–87%)
Effort: Comfortably hard
Use: Tempo sessions, aerobic threshold
Check out: Running: What Is Zone 3 / Tempo?
Zone 4 / Threshold (87–93%)
Effort: Hard but sustainable
Use: Race prep, lactate tolerance
Zone 5 / VO2 Max (93–100%)
Effort: Very hard
Use: Short intervals, top-end sharpening
Check out: Running: What Is Zone 5 / VO2 Max?
Use our free calculator to find your exact heart rate zones.
Why Elite Runners Rely on Threshold Training
Elite runners don’t guess effort. They train by feel and precision. Threshold work is how they build control, develop race pace and fine-tune intensity.
Zone 4 is a staple for elites because it allows them to:
Train hard without overtraining
Maintain high mileage with manageable stress
Simulate race efforts in training conditions
It’s not about going all out. It’s about being just fast enough, for just long enough, to create lasting adaptations.
FAQs: Zone 4 for 5K Runners
How often should I do Zone 4 sessions?
Once per week during race build is ideal.
Is Zone 4 the same as tempo?
Not quite. Tempo is usually Zone 3. Threshold is slightly harder and more specific.
Can beginners use Zone 4?
Yes. Only after 4–6 weeks of base building.
How long should a Zone 4 interval be?
Anywhere from 4–10 minutes, depending on experience and recovery.
What’s the risk of overdoing it?
You’ll burn out quickly, lose endurance and increase injury risk. Keep it focused.
Further Reading: Explore the Full 5K Zone Series
Keep building your knowledge with the rest of the 5K training zone guides:
5K Training: What Is Zone 1 / Recovery?
5K Training: What Is Zone 2 / Endurance?
5K Training: What Is Zone 3 / Tempo?
5K Training: What Is Zone 5 / VO2 Max?
Training Sessions:
5K Training: 10 Zone 4 / Threshold Workouts
5K Training: 10 Essential Sessions
Final Thoughts: Learn to Run on the Edge
Zone 4 is where smart discomfort lives. It’s not chaos. It’s control. It’s where your fitness meets race execution. By training here, you build the skills and strength to race hard from start to finish. You become a better pacer, a tougher runner and a more confident competitor.
Ready to master Zone 4 and crush your next 5K?
Always consult with a medical professional or certified coach before beginning any new training program. The information provided is for educational purposes only and is not a substitute for personalized advice.
