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 is not a sprint and it is not a cruise. It is that place just on the edge where you are pushing hard yet still holding form. Half marathon runners need this ability more than any other because the race demands strong pressure for long stretches without falling apart. Threshold running trains your body to handle that stress. It boosts efficiency, raises your lactate threshold and helps you maintain pace when the pressure builds. It teaches you how to stay composed at speed and trust your ability to keep moving smoothly when the effort is high.

What Is threshold Running?

Zone 4 training is also known as your threshold zone. During this phase lactate accumulation continues to increase to the point where it is around one’s lactate threshold. Running in this zone helps you handle that rising build up so you can stay strong for longer and maintain form as the effort tightens.

Zone 4 Defined:

  • Heart Rate: 87 to 93% of Max HR

  • Effort Level: 7 to 8 out of 10

  • Breathing: Heavy but controlled

  • Pace: Around 5K pace for most runners

You will feel the effort and that is the point. It should still feel controlled. You are running strong not struggling and you should feel able to hold your form even as the work rises. Zone 4 rewards focus and consistency and when you get it right it becomes the training that lifts your race day pace.

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 keep your form together when the effort begins to rise late in the race. It builds the strength and control needed to lift your pace without slipping into overload which is why it becomes so important in the sharpening phase of your plan.

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. It teaches you how to stay committed when the pressure builds and gives you the confidence to finish strong on race day.

How Zone 4 Feels While Running

Zone 4 feels tough but not overwhelming. It sits right on the line between effort and over effort. When you get it right the work is demanding yet still controlled and you stay focused as the pressure builds. This is the zone where you feel the effort rising in waves yet you are able to meet it with good form and steady breathing. It is challenging in a way that sharpens your concentration and teaches you how to stay composed when the pace begins to bite.

Effort Cues:

  • Short Words Only: You can say short words but full sentences are not possible

  • Rising Leg Effort: Legs feel strong yet the load builds across the interval

  • Heavy Breathing: Breathing is laboured but never panicked

  • Controlled Pressure: You are working hard but not fading

  • Clear Focus: You need to stay mentally locked in to hold rhythm

  • Steady Form: Your stride stays smooth even as the work increases

It is a pace you could hold for 20 minutes to an hour but it would take real focus to stay composed and maintain your rhythm from start to finish.

When to Use Zone 4 in a Half Marathon Plan

Zone 4 training becomes most important in the final 6 to 8 weeks before your race. Once you have built your aerobic base with Zones 1 to 3 this is when threshold work starts converting that foundation into real race readiness. It strengthens the ability to handle sustained pressure and prepares you for the harder miles late in the race when pace and control matter most.

Smart Uses of Zone 4:

  • Intervals: Break threshold pace into shorter controlled efforts

  • Threshold Blocks: Repeated longer controlled efforts in Zone 4

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

  • Standalone Threshold Runs: Run 20 to 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 and when your body is ready to absorb the higher workload without losing consistency.

Sample Zone 4 Workouts for Half Marathon

These sessions are designed to build lactate tolerance and prepare your body for race day pacing. Each workout helps you stay strong under pressure and teaches you how to control effort when the intensity rises.

Option 1: Threshold Intervals

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

  • Controlled effort with smooth pacing

  • Ideal for building time at threshold without overloading

Option 2: Steady Threshold Run

  • 20 to 30 minutes continuous Zone 4

  • Hold strong pace and form

  • Focus on breathing rhythm and smooth mechanics

Option 3: Progressive Long Run Finish

  • Total time: 75 to 90 minutes

  • Final 20 minutes in Zone 4

  • Simulates late race effort under fatigue

Option 4: Pyramid Threshold Set

  • 5 minutes 10 minutes 15 minutes 10 minutes 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 running so you absorb the work and stay consistent across your training week.

Common Mistakes with Zone 4 Training

Zone 4 can be demanding and it only works if you use it right. It rewards control and consistency so small errors can make the session feel harder than it should. This is the zone where discipline matters because you are working close to your limit and the quality of your effort shapes the outcome of your training.

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: Do not chase pace, train at the right effort and heart rate

  • Inconsistent Pacing: Starting too fast and fading ruins the quality of the session

  • Poor Warm Up: Entering Zone 4 without preparation makes the session feel harder than needed

  • Ignoring Form: Letting posture or stride fall apart increases strain without benefit

Zone 4 is about control not chaos. Your best results come when you train smart not just hard and give your body the space to absorb the intensity. When you approach these sessions with patience and focus they become some of the most powerful workouts in your entire half marathon plan.

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.

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. It gives you the ability to stay steady when the pressure builds and keeps your form strong when the race moves into the harder miles.

What Makes It Effective:

  • Race Day Simulation: Mimics race day effort and conditions

  • Lactate Clearance: Teaches your body to clear lactate and keep going

  • Mental Sharpness: Trains your mind to stay sharp under discomfort

  • Pace Control: Helps you lock into goal pace and hold it

When you consistently train at threshold your ability to run hard with control improves dramatically and the pace that once felt demanding begins to feel sustainable.

Why the Pros Use Zone 4

Elite runners rely on Zone 4 because it builds the strength and control needed to run fast for long periods. Threshold work raises the pace they can hold without fading and teaches them how to stay composed when the effort rises. Pros use it to strengthen the point just below their limit so race pace feels smoother and more sustainable. It is the zone that improves efficiency at speed and sharpens the ability to handle pressure late in a race.

Why elites trust threshold work:

  • Stronger Base Speed: Threshold work lifts the pace you can hold without breaking down

  • Stronger Ability to Hold Fast Pace: Helps maintain speed late in the race

  • Better Control Under Rising Fatigue: Keeps form steady when the effort builds

  • Higher Quality Work Without Excessive Recovery: Adds fitness without heavy strain

  • Improved Race Day Rhythm And Confidence: Helps you settle into sustainable pressure

Zone 4 is the training that lifts a strong half marathon from steady to fast and it is a non negotiable part of every elite plan.

FAQs: Zone 4 for Half Marathon Runners

Is Zone 4 the same as race pace?
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 session be?
From 20 to 60 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: the Half Marathon Series

Training Sessions:

Final Thoughts: Run to the Edge, Stay There

Zone 4 is where you learn to run hard without losing control. It sharpens your pacing, strengthens your focus and prepares you for the late race grind. This is the work that teaches you how to stay calm when the effort rises and how to hold form when the pressure builds. When you stay consistent with threshold training the pace that once felt demanding becomes the pace you can rely on. It gives you the confidence to push when others fade and the strength to finish your half marathon with purpose and control.

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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