After seven weeks of progressive intensity work – VO2max intervals, Sweet Spot efforts, lactate shuttles, threshold blocks, pyramids – it’s time for something that might seem counterintuitive: backing off the intensity while extending the duration. Meet the 105min Endurance Undulations – an extended aerobic session that develops deep metabolic flexibility through alternating Zone 1 and Zone 2 efforts.
This isn’t “going easy” because you’re tired. This is strategic aerobic development that builds the foundation everything else sits on. While last week’s pyramid taught you progressive intensity management, this week teaches sustained endurance with intelligent variation – exactly what your body needs right now.
The Undulating Endurance Approach
You’ve already experienced foundational endurance work in Week 1 with the 55-minute Zone 2 session. That was your introduction to aerobic base building. This workout takes that concept and extends it significantly – nearly doubling the duration while adding a crucial element: undulations between Zone 1 (55-65% FTP) and Zone 2 (65-75% FTP).
What makes this different from simply riding easy for 105 minutes? The structured variation. You’re not cruising at one steady power for nearly two hours. You’re alternating every 15 minutes between easier (Zone 1) and moderate (Zone 2) efforts, creating a wave pattern that trains your body to shift between energy systems efficiently.
Think of it as extended intervals, but at intensities so low you can maintain them for 15 minutes at a time without accumulating significant fatigue. The Zone 1 blocks teach fat oxidation and aerobic efficiency. The Zone 2 blocks develop sustainable endurance power. Together, they create metabolic flexibility – your body’s ability to smoothly shift fuel sources and intensity levels.
This is the workout professional cyclists do on their “easy days” between hard training blocks. It looks simple on paper. In execution, 105 minutes of focused riding requires mental discipline and physical endurance you might not have had seven weeks ago. But now? You’re ready.
Why Endurance Undulations Matter Now
After seven weeks of progressive intensity, you might be wondering: why back off to Zone 1 and 2? Shouldn’t we keep pushing harder?
Here’s the thing about fitness: it’s not built in a straight line. You can’t hammer intensity week after week indefinitely. Your body needs different stimuli at different times. Right now, after accumulating seven weeks of training stress including an FTP test and a challenging pyramid, your body needs volume at low intensity more than another hard session.
Endurance undulations deliver several benefits that high-intensity work can’t:
Deep aerobic development. Zone 1-2 work builds mitochondrial density, increases capillary networks, and enhances oxygen delivery to muscles. These adaptations happen best at lower intensities over extended durations.
Metabolic flexibility. Alternating between Zone 1 and 2 every 15 minutes trains your body to shift fuel sources efficiently – critical for long events where you can’t rely solely on carbohydrates.
Active recovery under load. You’re accumulating training time without the neuromuscular fatigue of high-intensity work. Your aerobic system develops while your threshold and VO2max systems recover from previous weeks.
Mental endurance. Maintaining focus for 105 minutes builds psychological capacity for long rides and events. This is as much a mental workout as physical.
Durability. Extended time in the saddle builds the resilience needed for centuries, gran fondos, or any event lasting 3+ hours. You’re teaching your body to function effectively when time in the saddle accumulates.
Think of this as consolidation. You’ve pushed hard for seven weeks. Now you’re cementing those gains with quality volume that doesn’t interfere with recovery while still providing meaningful training stimulus.
The Workout Breakdown
Total Time: 105 minutes
Intensity: 4/10
Training Stress Score (TSS): ~65
Structure:
- 5 minutes Easy Warmup (40-55% FTP): Light intensity preparation
- 5 minutes Build Warmup (55-70% FTP): Gradually increasing to working zones
- Undulation Pattern (repeated 3 times):
- 15 minutes Easy Endurance – Zone 1 (55-65% FTP)
- 15 minutes Endurance – Zone 2 (65-75% FTP)
- 5 minutes Cool Down (40-55% FTP): Gradual recovery
Total working time: 90 minutes alternating between Zone 1 and Zone 2 in 15-minute blocks. The pattern creates a gentle wave that keeps your mind engaged while maintaining purely aerobic intensity throughout.
What makes this structure effective is the duration of each block. Fifteen minutes is long enough to fully settle into each zone, allowing your metabolism to adjust and your body to accumulate time at that intensity. It’s also short enough that the transitions keep your mind occupied – you’re always working toward the next shift.
The 3x pattern means you experience the full undulation cycle three complete times. By the third cycle (minutes 75-105), you’ll understand what sustained endurance actually feels like. Your legs will have accumulated fatigue, but it’s aerobic fatigue, not the neuromuscular exhaustion of high-intensity work.
What It Actually Feels Like
The first 10 minutes of warm-up feel like barely riding. You’re easing into it, loosening up, finding your rhythm. Nothing hurts, nothing’s hard, you’re just moving.
The first Zone 1 block (55-65% FTP) feels almost comically easy. If you’ve been following this series, this intensity is lower than anything you’ve done since Week 1. You’ll be tempted to push harder. Don’t. The workout depends on staying in zone.
When you shift to Zone 2 (65-75% FTP), there’s a noticeable but not dramatic increase. You’re breathing slightly deeper. Your legs engage slightly more. But you’re nowhere near threshold or even tempo. This is truly sustainable endurance pace – the power you could theoretically maintain for 4-6 hours.
Back to Zone 1 for the second cycle, and here’s where it gets interesting: Zone 1 now feels like relief compared to Zone 2, even though the absolute power difference is small. Your heart rate drops noticeably. Breathing eases. You recover slightly while still working.
By the third cycle (starting around minute 60), the cumulative time in the saddle starts registering. Zone 1 still feels manageable, but you’re aware you’ve been riding for an hour. Zone 2 requires more focus than it did in cycle one. Not because it’s harder, but because you’re accumulating aerobic fatigue.
Minutes 75-90 test your mental endurance as much as physical. The work isn’t hard, but maintaining discipline to stay in zone for this long requires focus. Your mind will wander. You’ll think about stopping early. You’ll question whether this is “real training.” Stay the course.
The final 5-minute cooldown feels like a well-earned finish line.
The Benefits You’ll Notice
After including extended endurance sessions like this (once every 7-10 days):
Your aerobic capacity deepens significantly. Power that used to feel like “working” starts feeling like your natural cruising pace. Your aerobic engine strengthens from the foundation up.
Fat oxidation improves dramatically. Your body becomes more efficient at using fat for fuel at higher intensities, preserving glycogen for when you actually need it. This translates directly to better endurance on long rides.
Recovery between hard sessions accelerates. The increased mitochondrial density and capillary networks built through Zone 1-2 work mean your body can clear metabolic waste and deliver oxygen more efficiently during recovery.
Long ride confidence grows. After completing 105 minutes of focused riding, 2-hour group rides or 3-hour weekend epics feel psychologically manageable. You know you can sustain effort for extended periods.
Your “all-day pace” increases. The power you can comfortably maintain for hours gradually climbs as your aerobic base strengthens. Weekend rides that used to feel like efforts become conversational pace.
How to Execute It Properly
Stay religiously in zone. Zone 1 means 55-65% FTP. Zone 2 means 65-75% FTP. The moment you drift to 78-80% thinking “close enough,” you’ve undermined the workout. Discipline on these easy sessions matters as much as discipline on hard sessions.
Make the transitions smooth. When shifting from Zone 1 to Zone 2, don’t surge. Add power gradually over 30-60 seconds. Same when dropping back to Zone 1 – ease down gently. The transitions should be barely perceptible.
Fuel appropriately. 105 minutes at Zone 1-2 intensity still burns 500-800 calories depending on your size and FTP. Consume 30-40 grams of carbs per hour. Use this as an opportunity to practice fueling strategies for longer events.
Hydrate consistently. Set a timer to drink every 15 minutes (conveniently, at each zone transition). Two bottles minimum, three if it’s warm. Don’t wait until you’re thirsty.
Entertainment is encouraged. Unlike high-intensity sessions requiring total focus, endurance undulations allow podcasts, music, movies, or conversation if riding with others. Keep your mind engaged.
Cadence stays comfortable. 85-95 rpm for most riders. This isn’t low-cadence strength work or high-cadence spin practice. Find your naturally efficient cadence and maintain it throughout.
Position varies. Shift positions regularly – hands on hoods, drops, tops. Stand briefly every 15-20 minutes. This prevents numbness and stiffness while building the positional endurance needed for long events.
No Power Meter? Here’s Your Guide
Heart rate works excellently for this workout:
- Zone 1 (55-65% FTP): 55-65% max HR, very easy breathing, could easily hold conversation
- Zone 2 (65-75% FTP): 65-75% max HR, slightly elevated breathing, conversation comfortable
The talk test is perfectly reliable:
- Zone 1: Could explain complex work project in detail without colleague knowing you’re exercising
- Zone 2: Could discuss weekend plans comfortably but wouldn’t want to present a meeting
RPE for the full workout should stay 3-5 out of 10 maximum. If you finish feeling like you “worked out hard,” you went too hard. Goal is to finish feeling like you moved for 105 minutes but aren’t exhausted.
Indoor vs. Outdoor Execution
Indoor advantages:
- Perfect power control – hit zones precisely
- No interruptions (traffic, lights, weather)
- Mental challenge of staying engaged for 105 minutes
Outdoor advantages:
- Time passes faster with changing scenery
- More mentally engaging naturally
- Builds real-world riding skills
- Often more enjoyable
Both work. Choose based on what helps you complete the full 105 minutes with better quality. Many riders find outdoor execution significantly easier psychologically for extended endurance work, even though power control is less precise.
Time-Crunched Alternatives
Can’t commit to 105 minutes? The undulation concept scales:
75-minute version: 2 complete cycles (2x15min Zone 1, 2x15min Zone 2) with warmup and cooldown. Still builds aerobic base in less time.
60-minute version: Cut to 10-minute blocks instead of 15. Three complete cycles (3x10min Zone 1, 3x10min Zone 2). Maintains the undulation benefit in standard workout length.
Extended version: For riders with more time, extend to 135 minutes (4 complete cycles). Elite riders regularly do 3-4 hour rides entirely in Zone 1-2.
Just remember: the benefit of extended endurance comes partly from the extended duration. Sixty minutes at Zone 2 is valuable. 105 minutes provides significantly more adaptation specifically because of the duration.
The Mental Challenge
Here’s what most riders discover: 105 minutes at low intensity is harder mentally than 45 minutes of intervals. During intervals, you suffer, but time passes quickly because you’re counting down seconds. During extended endurance, time moves slowly and you have to actively maintain discipline to stay easy.
Your ego will sabotage this workout if you let it. “This feels too easy. I should push harder. I’m barely working.” All of these thoughts miss the point. The training stimulus comes from accumulated time at aerobic intensity, not from how hard it feels moment to moment.
Professionals embrace these sessions because they understand: different adaptations require different stimuli. Sometimes you need to suffer at threshold. Sometimes you need to accumulate hours at Zone 2. Both matter. Both make you faster. The key is doing each one properly when prescribed.
Getting Started This Week
Find the 105min Endurance Undulations at velovostra.com/workouts.
Free download, personalized zones, compatible with all platforms. You know the system.
Schedule this on a weekend. 105 minutes doesn’t fit most weeknight schedules. Saturday or Sunday morning when you have time and aren’t rushing. Make it a cornerstone session for the week.
Set up properly. Indoors: fan, water bottles, entertainment, towel. Outdoors: route planning (consistent terrain, minimal stops), nutrition, hydration, weather check. Don’t just wing it.
Your goal: complete all 105 minutes with power staying disciplined in prescribed zones. If your power file shows clean 15-minute blocks alternating between Zone 1 and Zone 2, you’ve executed perfectly.
Next Week’s Preview
After accumulating serious aerobic volume this week, next week brings strategic recovery. Not complete rest, not more endurance work – professional active recovery that enhances adaptation while allowing your body to absorb eight weeks of progressive training stress.
Want Workouts That Balance Volume and Intensity?
Individual sessions like this endurance undulation are excellent for building aerobic capacity. But optimal training requires intelligent integration of high-intensity work, moderate volume, and extended aerobic sessions – each at the right time in the right amounts.
VeloVostra creates complete training plans that balance these different stimuli strategically. You’re never guessing whether you need more intensity or more volume. Every workout fits purposefully into weekly structure designed to maximize adaptation while managing fatigue.
Whether you’re training 5 hours weekly or 15, whether targeting events or consistent improvement, there’s a structured approach that delivers the right workout at the right time.
How did the endurance undulations treat you? Did you discover that maintaining discipline at low intensity for 105 minutes requires different skills than crushing high-intensity intervals? Let me know – and if you want more extended endurance options, check out the complete workout library for everything from 60-minute Zone 2 rides to 3-hour aerobic epics.
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