Olympic Triathlon: What Is Zone 4 / Threshold Training?
SUMMARY:
Zone 4, around 87–93% of max heart rate, 91–105% of FTP and 99–104% of CSS swim speed (RPE 7–8) is the threshold zone that builds speed endurance and race control for Olympic triathlon. It feels hard but steady, right near your sustainable limit. Training in this zone improves your ability to hold faster paces, clear fatigue more efficiently and perform with strength across all three disciplines.
What Is Threshold Training?
When you’re preparing for an Olympic triathlon, logging easy miles isn’t enough. To truly race the 1.5 km swim, 40 km bike and 10 km run, you need to build speed, resilience and power. That’s where Zone 4 training comes in. Zone 4 sharpens your ability to sustain hard efforts when it matters most. These sessions target your lactate threshold, the intensity where lactate is produced at higher levels but your body is still able to clear it efficiently.
Whether you’re surging up a hill, fighting off competitors or gunning for a PR finish, training in this zone is essential for race-day success. Zone 4 is known as the threshold zone, a hard, but controlled effort level just under your maximum sustainable output. Training here boosts your ability to perform at high intensity without tipping into total fatigue.
Zone 4 Defined:
Heart Rate: 87–93% of HRmax
Perceived Effort: Hard (talking limited to short phrases) (RPE 7–8)
Cycling Power: 91–105% of FTP
CSS swim speed: 99–104%
Check out our Training Calculators — Pace, Power and Heart Rate.
It’s challenging, but manageable and it teaches your body and mind how to operate effectively under pressure.
Why Threshold Training Is Essential
1. Increases Lactate Threshold
The higher your lactate threshold, the longer you can sustain strong efforts without slowing down, a game-changer on the Olympic triathlon course.
2. Builds Speed and Power
Zone 4 efforts develop the strength and explosiveness needed for race surges, breakaways and tough climbs.
3. Prepares You for Real Race Intensity
Olympic triathlons aren’t just steady-state efforts; they require shifts in pace and grit. Zone 4 simulates these demands.
4. Builds Mental Grit
Holding Zone 4 intensity demands focus and mental toughness, essential skills when racing gets uncomfortable.
How to Integrate Zone 4 Into Your Olympic Triathlon Training
Zone 4 Running Workout
Main Set: 4 x 5 minutes at Zone 4 effort, with 2-minute easy jog recovery
Progression: Add more intervals or extend efforts to 6–8 minutes as fitness improves
Key Focus: Maintain good form even as fatigue creeps in.
Zone 4 Cycling Workout
Main Set: 5 x 4 minutes at 90–105% FTP, with 3-minute easy spin recovery
Progression: Increase to 6 reps or add slight elevation changes.
Key Focus: Smooth, consistent power through each rep.
Zone 4 Swimming Workout
Main Set: 8 x 100 meters at Zone 4 effort, 30 seconds rest between intervals
Progression: Build to 10–12 x 100 meters or reduce rest for a bigger challenge.
Key Focus: Powerful strokes with efficient breathing at a high effort.
How Often Should You Include Threshold Sessions?
To get the full benefits of threshold training without overreaching, it’s important to apply Zone 4 work with intention. Use these general guidelines to structure your week.
Swim: 1–2 times per week
Bike: 1–2 times per week
Run: 1 time per week (with a possible second during peak training phases)
Pro Tip: Always balance hard Zone 4 efforts with easy recovery sessions to avoid overtraining.
Consistency matters, but so does recovery. Let your body absorb the hard work by balancing these sessions with lower-intensity training throughout the week.
Top Tips for Effective Zone 4 Training
Prioritise a Proper Warm-Up
Spend 10–15 minutes easing into your workout with Zone 2 effort and dynamic drills.Focus on Quality Over Quantity
Short, intense intervals are better than grinding through junk miles.Use Recovery Wisely
Plan 1:1 or 1:1.5 work-to-rest ratios to keep efforts high-quality.Stay Data-Driven
Use heart rate, power or pace metrics to make sure you’re training at the right intensity.Don’t Overdo It
Zone 4 work is potent. Stick to 1–2 hard sessions weekly and prioritise recovery days after.
Common Pitfalls to Avoid
Even well-intentioned sessions can go wrong if you overlook the basics. Here are three common mistakes to watch for when executing your Zone 4 Training.
Starting too fast: Stay controlled early in the interval to sustain effort through the end.
Skipping warm-ups: Increases injury risk and reduces session quality.
Neglecting rest: Without enough recovery, fitness gains stall and fatigue builds.
Avoiding these pitfalls helps you get the most out of every threshold session and build consistent Zone 4 Training fitness across your Olympic training block.
FAQ: Zone 4 Training for Triathlon
Should Zone 4 intervals feel painful?
They should feel hard and challenging, but sustainable for the interval duration, not max sprint efforts.
Can beginners benefit from Zone 4 training?
Yes, but start conservatively with shorter reps and fewer sets to build up safely.
How long should Zone 4 workouts last?
Typically 30–60 minutes including warm-up, main set and cool-down.
Can I combine Zone 4 workouts with brick sessions?
Absolutely! A Zone 4 bike followed by a short run is excellent for sharpening race-day skills.
FURTHER READING: BUILD YOUR OLYMPIC POWER
Olympic Triathlon: What Is Zone 2 / Endurance?
Olympic Triathlon: What Is Zone 3 / Tempo?
Olympic Triathlon: What Is Zone 5 / VO2 Max?
Olympic Triathlon: 10 Threshold Swim Sessions
Olympic Triathlon: 10 Threshold Bike Sessions
Olympic Triathlon: 10 Threshold Run Sessions
Olympic Triathlon: Recovery Week
Olympic Triathlon: Beginner’s Guide
Final Thoughts
Zone 4 training is where speed, strength and stamina truly come together in harmony. By consistently pushing your threshold and carefully honing your ability to sustain these hard, intense efforts, you’ll not only race faster but also respond more effectively to sudden surges during competition, ultimately allowing you to finish stronger in your Olympic triathlon. Begin incorporating well-structured Zone 4 sessions into your regular training routine and unlock the next level of your triathlon performance like never before!
Are you ready to break through your limits?
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 personalised advice.
