Sprint Triathlon Training: 10 Threshold Brick Sessions
Summary
Threshold / Zone 4 brick sessions combine bike and run efforts at a challenging but controlled intensity, perfect for building speed, endurance, and race-day execution. These workouts target your lactate threshold: 87–93% of max heart rate, 91–105% of FTP or a 7–8 RPE. By training both disciplines back-to-back at this level, you’ll improve fatigue resistance, sharpen pacing and run stronger off the bike. These 10 sessions are built to help you train smarter and perform better in sprint triathlon racing.
What Is Zone 4 / Threshold Training?
Zone 4 is your threshold zone. It sits between 87–93% of your maximum heart rate and 91–105% of your FTP on the bike. On the RPE scale, it feels like a 7 to 8 out of 10. Breathing is deep and focused. You can hold the pace but it takes control. You are not sprinting but you are working hard to stay consistent. This zone builds your ability to stay strong under pressure. It teaches your body to hold form when the effort rises. You are pushing, but still just inside your limit. That is what makes it one of the most effective zones for race-specific fitness.
Why These Sessions Work
Threshold brick sessions prepare your body and mind for the toughest part of a sprint triathlon, running strong off a hard bike. These workouts build control, strength and discipline. They help you manage fatigue and stay composed when the race starts to hurt. Training in Zone 4 improves your ability to hold effort without slowing down. It also builds the mental focus to stay sharp when things get uncomfortable. These sessions develop both your speed and your control, making them essential for sprint-distance racing.
Threshold Intensity Guidelines
Threshold efforts sit just below your redline, they are challenging and demanding, yet still manageable and sustainable for a prolonged period.
Here’s how to gauge intensity:
Heart Rate (HR): 87–93% of max HR
FTP (Cycling): 91–105% of FTP
RPE (Perceived Effort): 7-8
Use the FLJUGA Zone Calculator to dial in your training zones.
Below are 10 key threshold brick sessions to elevate your performance.
Threshold Brick Workout
1. Short Threshold Brick
Purpose: Build intensity tolerance at sprint race pace
Bike Warm-Up: 10 min spin + 3 cadence lifts
Bike Main Set: 3 x 8 min @ Zone 4 (3 min spin between)
Transition Jog: 5 min easy jog
Run Main Set: 3 x 4 min @ Zone 4 (2 min jog recoveries)
Cool-Down: 10 min jog
2. Fast-Finish Brick
Purpose: Practice strong finish off high-end aerobic load
Bike Warm-Up: 10 min spin
Bike Main Set: 20 min @ Zone 3, 10 min @ Zone 4
Transition Jog: 5 min easy jog
Run Main Set: 10 min @ Zone 3, 5 min @ Zone 4
Cool-Down: 10 min jog
3. Over-Under Threshold Brick
Purpose: Handle pace changes and recover just below threshold
Bike Warm-Up: 12 min spin
Bike Main Set: 4 x (3 min @ Zone 3 + 4 min @ Zone 4)
Transition Jog: 5 min easy jog
Run Main Set: 3 x (2 min @ Zone 3 + 3 min @ Zone 4)
Cool-Down: 10 min jog
4. Repeating Brick Intervals
Purpose: Develop repeatable race-intensity efforts under fatigue
Bike Warm-Up: 10 min spin
Bike Main Set: 3 x 10 min @ Zone 4 (3 min spin between)
Transition Jog: 5 min easy jog
Run Main Set: 3 x 6 min @ Zone 4 (2 min jog recoveries)
Cool-Down: 10 min jog
5. Progressive Brick Builder
Purpose: Increase intensity through each phase of the session
Bike Warm-Up: 12 min spin
Bike Main Set: 10 min @ Zone 3, 10 min @ Zone 4
Transition Jog: 5 min easy jog
Run Main Set: 5 min @ Zone 3, 5 min @ Zone 4
Cool-Down: 10 min jog
6. Big Gear Threshold Brick
Purpose: Build strength and muscular control at threshold
Bike Warm-Up: 12 min spin + cadence work
Bike Main Set: 3 x 8 min @ Zone 4 (big gear, low cadence) (3 min spin between)
Transition Jog: 5 min easy jog
Run Main Set: 2 x 8 min @ Zone 4
Cool-Down: 10 min jog
7. Double Threshold Set
Purpose: Train both bike and run at race-specific intensity with minimal recovery
Bike Warm-Up: 10 min spin
Bike Main Set: 2 x 15 min @ Zone 4 (5 min spin between)
Transition Jog: 5 min easy jog
Run Main Set: 2 x 10 min @ Zone 4 (3 min jog between)
Cool-Down: 10 min jog
8. Split Brick Format
Purpose: Stack bike-run efforts with partial recovery to simulate late-race fatigue
Bike Warm-Up: 10 min spin
Bike Main Set: 15 min @ Zone 4 (5 min spin), 10 min @ Zone 4
Transition Jog: 5 min easy jog
Run Main Set: 10 min @ Zone 4, 5 min @ Zone 3
Cool-Down: 10 min jog
9. Threshold Tempo Combo Brick
Purpose: Blend controlled pacing with sharp efforts under fatigue
Bike Warm-Up: 12 min spin
Bike Main Set: 30 min @ Zone 3, 10 min @ Zone 4
Transition Jog: 5 min easy jog
Run Main Set: 10 min @ Zone 3, 5 min @ Zone 4
Cool-Down: 10 min jog
10. Race Simulation Brick
Purpose: Mimic full sprint-distance pacing and intensity
Bike Warm-Up: 10 min spin
Bike Main Set: 20 min @ Zone 4
Transition Jog: 5 min easy jog
Run Main Set: 15 min @ Zone 4
Cool-Down: 10 min jog
Mini FAQ: Threshold Brick Sessions
What is a brick session in triathlon training?
A brick session combines two disciplines back-to-back, usually cycling followed immediately by running, to simulate race-day conditions and improve transition performance.
What does “threshold” mean in these workouts?
Threshold refers to training in Zone 4, at or near your lactate threshold. It improves endurance, pacing control and fatigue resistance.
How often should I do threshold brick sessions?
Once per week is ideal for sprint triathletes during build phases. Include recovery weeks to avoid overtraining.
Are threshold bricks suitable for beginners?
Yes. With modifications. Beginners can reduce the duration or intensity to stay within their current fitness level while still gaining benefits.
FURTHER READING: BUILD THRESHOLD STRENGTH
Triathlon Training: What Is Threshold Training / Zone 4?
Sprint Triathlon: What Is Zone 4 / Threshold?
Sprint Triathlon: When to Take a Recovery Week
Sprint Triathlon: 10 Tempo Brick Sessions
Sprint Triathlon: 10 Key Brick Sessions
Final Thoughts
Threshold bricks are key to developing race-day speed, strength and endurance. Add these to your training plan and you’ll be ready to crush your next sprint triathlon! They teach you how to hold pace under pressure, recover just enough to go again and run hard off the bike, even on tired legs. Over time, that’s what builds real racing confidence. Rotate these sessions weekly, stay consistent and you’ll arrive at the start line sharp, strong, and ready to perform.
Ready to turn legs of lead into legs of steel?
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.
