Marathon Run Training: 10 Threshold Sessions
What Is Threshold Running in Ironman Training?
Threshold running is critical in Ironman training as it helps build sustained speed, endurance, and efficiency while improving your ability to clear lactate and maintain a strong pace deep into the marathon. These workouts train your body and mind to hold form under fatigue, manage effort more precisely, and stay strong through the later miles when most athletes fade. With the right threshold sessions, you’ll build the resilience to run with control — not just survive the marathon, but finish it strong.
In this post, you’ll find 10 threshold run sessions designed to build sustained speed, pacing control, and marathon strength for Ironman race day.
1. Classic Threshold Intervals
Purpose: Improves lactate clearance and enhances race-day pacing.
Session:
Warm-up: 15 min easy run
Main Set:
4–5 x 10 min at threshold pace (Zone 4 or ~85-90% HR max), 2 min easy jog recovery
Cool-down: 10 min easy jog
Focus: Holding a consistent, controlled effort just below your max sustainable pace.
2. Progressive Threshold Run
Purpose: Simulates race fatigue by increasing intensity over time.
Session:
Warm-up: 15 min easy run
Main Set:
4 x 10 min at increasing effort:
1st: Upper Zone 3 (steady)
2nd: Low Zone 4 (moderate-hard)
3rd & 4th: Threshold pace (Zone 4)
Cool-down: 10 min
Focus: Building resilience and pacing awareness for the latter stages of an Ironman run.
3. Long Run with Threshold Surges
Purpose: Mimics race conditions by adding intensity to a long aerobic session.
Session:
Warm-up: 5min easy run
Main Set:
90–120 min long run:
20 min easy warm-up
Every 15 minutes, insert 2 min at threshold effort
Last 20 min: Run at marathon race pace
Cool-down: 5 min
Focus: Practicing pace changes and endurance while maintaining form.
4. Tempo + Threshold Combo
Purpose: Blends sustained effort with threshold work for efficiency and endurance.
Session:
Warm-up: 15 min easy jog
Main Set:
20 min tempo effort (Zone 3)
4 x 5 min at threshold pace (Zone 4), 90 sec recovery
Cool-down: 10 min
Focus: Managing fatigue and maintaining good biomechanics under stress.
5. Broken Threshold Repeats
Purpose: Develops sustained speed without overloading the legs.
Session:
Warm-up: 15 min easy run
Main Set:
6–8 x 3 min at threshold pace, 60 sec recovery jog
Cool-down: 10 min
Focus: Holding consistent threshold pace across all reps without fading.
6. Threshold Hill Repeats
Purpose: Builds leg strength and threshold endurance.
Session:
Warm-up: 15 min easy run
Main Set:
6 x 3–4 min uphill at threshold effort, jog down for recovery
Cool-down: 10 min
Focus: Running strong and relaxed while maintaining cadence.
7. Marathon Pace + Threshold Run
Purpose: Combines race pacing with a threshold push to mimic late-race demands.
Session:
Warm-up: 15 min easy run
Main Set:
45 min at Ironman marathon pace (Zone 2-3)
15 min at threshold effort (Zone 4)
Cool-down: 10 min
Focus: Practicing strong finishes on tired legs.
8. Descending Threshold Intervals
Purpose: Improves ability to finish strong by increasing pace with each rep.
Session:
Warm-up: 15 min easy run
Main Set:
4 x 8 min at descending paces (slightly faster each rep), 90 sec recovery
Cool-down: 10 min
Focus: Building mental and physical endurance for negative splitting.
9. Threshold-Based Fartlek Run
Purpose: Improves speed endurance with varied efforts.
Session:
Warm-up: 15 min easy run
Main Set:
4 rounds of:
3 min at threshold pace
2 min at Ironman marathon pace
1 min at 5K pace
Cool-down: 10 min
Focus: Managing effort shifts without breaking rhythm.
10. Taper Threshold Tune-Up (7–10 days before race day)
Purpose: Maintains sharpness without overloading before race day.
Session:
Warm-up: 15 min easy jog
Main Set:
3 x 6 min at threshold pace, 2 min easy jog recovery
Cool-down: 10 min
Focus: Staying smooth, fast, and confident leading into race day.
Mini FAQ: Threshold Run Workouts for Ironman
What is threshold pace in running?
Threshold pace is the fastest pace you can sustain for about an hour—comfortably hard, but just below the point where fatigue rapidly builds.
Why are threshold sessions important for Ironman athletes?
They improve your lactate clearance, running efficiency, and mental strength—especially critical for staying strong in the final miles of the marathon.
How often should I include threshold runs?
Once per week is ideal during your build phase. Combine with aerobic and long run sessions for a balanced program.
What’s a typical threshold run session look like?
Example: 10-minute warm-up, 4 x 5-minute intervals at threshold pace with 90 seconds jog recovery, followed by a 10-minute cool-down.
Can beginners do threshold workouts?
Yes—just scale the intervals to your fitness level. Start with shorter reps (e.g., 3–4 minutes) and build as your endurance improves.
Final Thoughts:
These threshold sessions help improve speed, endurance, and pacing for the Ironman run. Integrating them 1–2 times per week in a structured plan will help you hold race pace longer and finish strong.
Add these sessions to your weekly plan and turn strength and speed into your race-day weapon!
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.