Half Marathon Training: What Is Zone 4 / Threshold?

Half MarathonZone 4 / Threshold
Written By FLJUGA

SUMMARY:
Zone 4, around 87–93% of max heart rate, RPE 7–8, represents threshold running. It feels hard but controlled, sitting just below your redline. For half marathon training, it sharpens your ability to sustain pace, improves lactate clearance and builds the toughness needed for race execution. In this guide, we’ll break down what Zone 4 running is, why it’s essential for half marathon runners and how to use it smartly in your plan.

Track surface showing the 800m mark, ideal for threshold intervals.

Find the Edge, Then Hold It

Zone 4 is where strength meets control. It’s not a sprint. It’s not a cruise. It’s that place just on the edge, where you’re pushing hard but still holding form. Half marathon runners need this ability more than any other: the capacity to run strong for long without falling apart. Threshold running trains your body to handle stress. It boosts efficiency, raises your lactate threshold and helps you maintain pace when the pressure builds. It’s not just about speed. It’s about staying composed at speed.

What Is Zone 4 Running?

Zone 4 training, also known as your threshold heart rate zone, sits at the point where your body starts to build up lactate faster than it can clear it. Running in this zone helps you handle that build-up so you can stay strong for longer.

Zone 4 Defined:

  • Heart Rate: 87–93% of Max HR

  • Effort Level: 7–8 out of 10

  • Breathing: Heavy but controlled

  • Pace: Just below 10K race pace for most runners

You’ll feel the effort and that’s the point. But it should still feel in control. You’re running strong, not struggling.

Why Zone 4 Matters in Half Marathon Training

The bulk of a half marathon is typically run in Zone 3, with Zone 4 coming into play in the final miles. Training in Zone 4 helps you hold speed, stay efficient and improve your race-day pace.

Top Benefits of Zone 4 Workouts:

  • Raises Lactate Threshold: Helps you sustain higher speeds without fatigue

  • Improves Pacing Control: Builds awareness of what sustainable hard effort feels like

  • Strengthens Mental Resilience: Trains your mind to stay focused under discomfort

  • Boosts Race-Day Specificity: Prepares you to hold target pace under real fatigue

  • Enhances Efficiency at Speed: Sharpens your stride and breathing under pressure

Threshold work is where race pace gets rehearsed and refined.

How Zone 4 Feels While Running

Zone 4 feels tough, but not overwhelming. It’s the line between effort and over-effort. When done right, it’s hard enough to build fitness but not so hard that you burn out.

Effort Cues:

  • You can’t talk, but you can concentrate

  • Legs feel strong, but the effort builds

  • Breathing is laboured, but not panicked

  • You’re working — but you’re not fading

It’s a pace you could hold for 20 to 40 minutes, but it wouldn’t be easy.

When to Use Zone 4 in a Half Marathon Plan

Zone 4 training becomes most important in the final 6–8 weeks before your race. Once you’ve built your aerobic base with Zones 1–3, threshold work helps convert that fitness into race-readiness.

Smart Uses of Zone 4:

  • Intervals: Break threshold pace into manageable efforts

  • Race Pace Workouts: Simulate goal half marathon effort

  • Progressive Long Runs: Finish long efforts with 15–20 minutes in Zone 4

  • Standalone Threshold Runs: Run 20–30 minutes at threshold without interruption

Avoid using it too early in your plan. It works best when you already have aerobic fitness and durability.

Sample Zone 4 Workouts for Half Marathon Runners

These sessions are designed to build lactate tolerance and prepare your body for race-day pacing.

Option 1: Threshold Intervals

  • 3 x 10 minutes at Zone 4 (2 min jog between)

  • Controlled effort, smooth pacing

  • Ideal for building time at threshold without overloading

Option 2: Steady Threshold Run

  • 20–30 minutes continuous Zone 4

  • Hold strong pace and form

  • Focus on breathing rhythm and smooth mechanics

Option 3: Progressive Long Run Finish

  • 75–90 minutes total

  • Final 20 minutes in Zone 4

  • Simulates late-race effort under fatigue

Option 4: Pyramid Threshold Set

  • 5-10-15-10-5 minutes at Zone 4

  • 90 sec jog recovery between

  • Trains control and pacing transitions

These sessions require full focus. Recovery between them should include easy Zone 1 or Zone 2 runs.

Common Mistakes with Zone 4 Training

Zone 4 can be demanding and it only works if you use it right.

Mistakes to Avoid:

  • Going Too Fast: Turning a threshold run into a VO2 max session

  • Skipping Recovery: Not allowing enough easy running between sessions

  • Doing Too Much Too Soon: Threshold work should come after a solid aerobic base

  • Racing Every Workout: Don’t chase pace. Train at the right effort and heart rate

  • Inconsistent Pacing: Avoid starting too fast and fading, aim for steady effort

Zone 4 is about control, not chaos. Your best results come when you train smart, not just hard.

Zone 4 vs Other Training Zones

Each training zone supports a different part of your half marathon development. Zone 4 is where fitness meets focus, the final sharpening tool before race day.

Use our free calculator to set your exact training zones before starting your plan.

Why Zone 4 Is the Key to Racing Fast

The half marathon is long enough to require endurance and short enough to require speed. Threshold training is the sweet spot where both meet. Zone 4 helps you pace smarter, stay in control and handle fatigue with confidence.

What Makes It Effective:

  • Mimics race-day effort and conditions

  • Teaches your body to clear lactate and keep going

  • Trains your mind to stay sharp under discomfort

  • Helps you lock into goal pace and hold it

When you consistently train at threshold, your ability to run hard with control improves dramatically.

FAQs: Zone 4 for Half Marathon Runners

Is Zone 4 the same as race pace?
Often, yes — especially in the final miles of a half marathon. But not always. Most runners stay in Zone 3 for the bulk of the race and only push into Zone 4 or 5 in the final stretch.

How often should I train in Zone 4?
Once every 7 days during your final build phase. Allow recovery days between.

Can beginners train in Zone 4?
Yes — but only after developing an aerobic base in Zones 2 and 3. Start with short intervals.

How long should Zone 4 efforts be?
From 8 to 30 minutes, depending on your fitness. You can break longer efforts into intervals.

What if I can’t hold Zone 4 pace?
Adjust based on effort or heart rate. Threshold isn’t about speed alone, it’s about sustainable discomfort.

Further Reading: Explore the Full Half Marathon Zone Series

Training Sessions:

Final Thoughts: Run to the Edge, Stay There

Threshold training isn’t glamorous. It’s not fast enough to feel exciting or easy enough to cruise through. But it’s the work that changes how you race. Zone 4 is the difference between holding strong and falling apart. Train here consistently and you’ll feel ready, steady and resilient when the race heats up.

Ready to reach Zone 4 and boost your half marathon speed and endurance?

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.

FLJUGA
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