Interval training is the most time-efficient way to improve cycling performance. By alternating between high-intensity efforts and recovery periods, you can build fitness faster than steady-state riding alone. This guide covers every type of cycling interval, from short anaerobic bursts to extended threshold efforts, with specific protocols to match your goals.
Why Interval Training Works
Interval training produces superior adaptations compared to steady riding because it accumulates more time at high intensities. During intervals, you challenge your cardiovascular system, muscles, and metabolism at levels impossible to sustain continuously.
Physiological Adaptations from Intervals
- • Increased mitochondrial density (more cellular power plants)
- • Enhanced capillary networks (better oxygen delivery)
- • Improved lactate threshold (higher sustainable power)
- • Greater cardiac stroke volume (more blood per heartbeat)
- • Enhanced fat oxidation (better fuel efficiency)
- • Increased glycogen storage capacity
- • Improved neuromuscular recruitment patterns
Research shows that 2-3 interval sessions per week can provide fitness gains equivalent to much longer steady rides. For time-crunched athletes, intervals maximize training stimulus per hour.
Energy Systems Explained
Understanding your body's three energy systems helps you select the right intervals for your goals:
| Energy System | Duration | Fuel Source | Cycling Application |
|---|---|---|---|
| ATP-PCr (Phosphagen) | 0-10 seconds | Stored ATP and creatine phosphate | Sprint finishes, jumps, attacks |
| Glycolytic (Anaerobic) | 10 seconds - 2 minutes | Muscle glycogen (without oxygen) | Short climbs, breakaways, surges |
| Oxidative (Aerobic) | 2+ minutes | Glycogen and fat (with oxygen) | Time trials, long climbs, endurance |
Most cycling efforts use a blend of systems. Interval training allows you to stress specific systems more than continuous riding permits.
Power Zones for Intervals
Power zones based on your Functional Threshold Power (FTP) provide precise intensity targets:
| Zone | Name | % of FTP | Primary Benefit |
|---|---|---|---|
| Zone 1 | Active Recovery | <55% | Recovery, warm-up |
| Zone 2 | Endurance | 56-75% | Aerobic base, fat oxidation |
| Zone 3 | Tempo | 76-90% | Muscular endurance |
| Zone 4 | Threshold | 91-105% | Lactate threshold improvement |
| Zone 5 | VO2max | 106-120% | Maximum aerobic capacity |
| Zone 6 | Anaerobic Capacity | 121-150% | Anaerobic endurance |
| Zone 7 | Neuromuscular Power | >150% | Peak power, sprinting |
Types of Cycling Intervals
Different interval formats target specific adaptations. Choose based on your racing demands and limiters:
Aerobic Intervals
- • Sweet spot (88-93% FTP)
- • Tempo (76-90% FTP)
- • Threshold (95-105% FTP)
- • VO2max (106-120% FTP)
Anaerobic Intervals
- • Anaerobic capacity (121-150% FTP)
- • Sprint intervals (>150% FTP)
- • Tabata protocol (all-out efforts)
- • Neuromuscular bursts
VO2max Intervals: Building Your Ceiling
VO2max intervals improve your maximum oxygen uptake capacity—the ceiling of your aerobic engine. These hard efforts at 106-120% FTP lasting 3-8 minutes are among the most effective for cycling performance.
Classic VO2max Workouts
Key principles: Start conservatively—it's better to finish strong than blow up early. Heart rate will drift upward throughout the interval, which is normal. Focus on consistent power rather than matching heart rate targets.
Threshold Intervals: Raising Your FTP
Threshold intervals at 95-105% FTP directly challenge your lactate threshold, increasing the power you can sustain for extended periods. These are essential for time trialists, climbers, and anyone wanting higher sustainable power.
Threshold Workout Progressions
Beginner: 2x15 minutes @ 95% FTP, 10 min recovery
Intermediate: 2x20 minutes @ 100% FTP, 10 min recovery
Advanced: 1x40-60 minutes @ 95-100% FTP continuous
Over-unders: Alternate 2 min @ 105% with 2 min @ 95% for 20 minutes
Over-under intervals are particularly effective for racing, teaching you to recover while still riding hard. They simulate race surges and attacks.
Sweet Spot Training: Maximum Efficiency
Sweet spot training at 88-93% FTP offers the best balance of training stimulus and recovery cost. You accumulate significant training stress with faster recovery than threshold work.
Why Sweet Spot Works
- • 90% of threshold benefit at 50% of the recovery cost
- • Sustainable for longer intervals (20-60+ minutes)
- • Builds muscular endurance and aerobic capacity
- • Excellent for time-crunched athletes
- • Can be performed 2-4 times per week
| Sweet Spot Workout | Structure | Total Time |
|---|---|---|
| SS Intro | 3x10 min @ 90% FTP, 5 min recovery | 45 min |
| SS Builder | 2x20 min @ 90% FTP, 10 min recovery | 50 min |
| SS Extended | 1x45 min @ 88% FTP continuous | 45 min |
| SS Ladder | 10-15-20-15-10 min @ 90%, 5 min recovery | 90 min |
Sprint & Anaerobic Intervals
Short, maximal efforts develop peak power and anaerobic capacity. These intervals are essential for criterium racing, breakaway efforts, and sprint finishes.
Sprint Workouts (5-15 sec)
Focus: Peak neuromuscular power
- • 8x10 sec all-out, 5 min recovery
- • 6x15 sec standing start sprints
- • 4x12 sec flying sprints from 25 mph
Anaerobic Capacity (30 sec - 2 min)
Focus: Sustained high power
- • 8x30 sec @ 150% FTP, 4 min recovery
- • 6x1 min @ 130% FTP, 3 min recovery
- • 4x2 min @ 120% FTP, 4 min recovery
Recovery is crucial: Sprint and anaerobic intervals require full recovery between efforts to maintain quality. Short recoveries create a different training stimulus (anaerobic endurance vs peak power).
Tabata Protocol: Maximum Intensity
The Tabata protocol—20 seconds all-out effort followed by 10 seconds rest, repeated 8 times—is one of the most researched and brutal interval formats. Originally studied by Dr. Izumi Tabata, it improves both aerobic and anaerobic systems.
True Tabata Requirements
- • 20 seconds at 170% VO2max (approximately 170% FTP)
- • 10 seconds complete rest or very easy spinning
- • 8 rounds (total 4 minutes of work)
- • Each effort should feel maximal by round 4-5
- • You should barely complete the final rounds
Warning: True Tabata efforts are extremely demanding. Most "Tabata" classes are modified versions. Limit to 1-2 sessions per week maximum, and don't attempt without a solid fitness base.
Structuring Your Interval Workout
Every interval session should include proper warm-up and cool-down phases:
Interval Session Template
Weekly Interval Planning
Most cyclists can handle 2-3 quality interval sessions per week. More isn't better—recovery enables adaptation.
| Weekly Volume | Interval Sessions | Recommended Distribution |
|---|---|---|
| 5-7 hours/week | 2 sessions | Tue/Thu or Tue/Sat |
| 8-12 hours/week | 2-3 sessions | Tue/Thu/Sat |
| 12+ hours/week | 3 sessions | Tue/Thu/Sat or Mon/Wed/Sat |
Sample Week (10 hours)
- Monday: Rest or 45 min recovery spin
- Tuesday: 1.5 hrs with VO2max intervals (5x5 @ 108%)
- Wednesday: 1 hr easy endurance
- Thursday: 1.5 hrs with threshold work (2x20 @ 100%)
- Friday: Rest or 45 min recovery
- Saturday: 2.5 hrs endurance with sweet spot (3x15 @ 90%)
- Sunday: 2.5 hrs group ride or long endurance
Progression Strategies
Progressive overload ensures continued adaptation. Use these methods to increase training stimulus over time:
Volume Progression
- • Add one interval per workout
- • Extend interval duration by 1-2 minutes
- • Add one more set
- • Progress: 3x10 → 4x10 → 4x12 → 5x10
Intensity Progression
- • Increase power by 2-3% when workouts feel easier
- • Shorten recovery periods
- • Retest FTP every 4-6 weeks
- • Progress: 95% FTP → 98% → 100% → 102%
Rule of thumb: Progress one variable at a time. If you add intervals, don't also increase intensity in the same week.
Recovery Between Intervals
Recovery duration significantly affects the training stimulus. Match recovery to your goals:
| Goal | Work:Rest Ratio | Example |
|---|---|---|
| Peak Power Development | 1:10 to 1:20 | 10 sec sprint, 3-5 min rest |
| VO2max Improvement | 1:1 to 1:1.5 | 5 min hard, 5-7 min easy |
| Threshold Improvement | 2:1 to 3:1 | 20 min hard, 7-10 min easy |
| Anaerobic Endurance | 1:2 to 1:4 | 1 min hard, 2-4 min easy |
| Repeatability/Racing | 1:0.5 to 1:1 | 2 min hard, 1-2 min easy |
Indoor vs Outdoor Intervals
Both environments have advantages. Smart athletes use each strategically:
Indoor Trainer Advantages
- • Precise power control (ERG mode)
- • No traffic, lights, or terrain interruptions
- • Perfect for structured intervals
- • Time-efficient (no travel time)
- • Weather-independent
- • Easy to track and compare workouts
Outdoor Riding Advantages
- • Real-world conditions and bike handling
- • Natural terrain for interval variety
- • Mental freshness and enjoyment
- • Better heat dissipation
- • Race simulation capability
- • Group ride opportunities
Pro tip: Many athletes do structured intervals indoors during the week and longer endurance rides outdoors on weekends. Indoor power typically feels 5-10% harder due to heat buildup and lack of inertia.
Common Interval Training Mistakes
1. Starting Too Hard
Blowing up on the first interval means poor quality on subsequent efforts. Start conservatively and build into the workout.
2. Not Enough Recovery
Insufficient rest between intervals reduces training quality. Honor the recovery—it's part of the workout.
3. Too Many Interval Sessions
More than 3 hard sessions per week leads to accumulated fatigue and stalled progress. Easy days must stay easy.
4. Ignoring Fatigue Signals
If power is down 10%+ from normal, cut the workout short. Training tired builds fatigue, not fitness.
5. Inconsistent Pacing
Surging and fading wastes energy. Use ERG mode or practice maintaining steady power throughout each interval.
Sample Interval Workouts
Beginner: Sweet Spot Intro (60 min)
Warm-up 15 min → 3x10 min @ 88-90% FTP with 5 min recovery → Cool-down 10 min
Intermediate: VO2max Builder (75 min)
Warm-up 20 min with 3x30 sec accelerations → 5x4 min @ 110% FTP with 4 min recovery → Cool-down 15 min
Advanced: Over-Under Threshold (90 min)
Warm-up 20 min → 3x12 min (alternating 2 min @ 105% / 2 min @ 95% FTP) with 8 min recovery → Cool-down 15 min
Race Prep: Varied Intensity (90 min)
Warm-up 20 min → 6x30 sec @ 150% FTP with 4 min recovery → 10 min @ Zone 2 → 2x15 min @ 95% FTP with 5 min recovery → Cool-down 10 min
Frequently Asked Questions
How often should I do cycling intervals?
Most cyclists benefit from 2-3 interval sessions per week, with at least 48 hours between hard efforts. Allow adequate recovery to prevent overtraining and maximize adaptation.
What are the best cycling intervals for beginners?
Beginners should start with tempo intervals (3-4 efforts of 8-10 minutes at 76-90% FTP) or sweet spot training (88-93% FTP). These build aerobic base without excessive fatigue.
How long should cycling intervals be?
Interval duration depends on your target energy system: 30 seconds to 2 minutes for anaerobic capacity, 3-8 minutes for VO2max, 8-20 minutes for threshold, and 20+ minutes for sweet spot/tempo work.
Do I need a power meter for interval training?
While not required, a power meter significantly improves interval training by providing objective intensity targets. You can use heart rate and perceived exertion, but power offers more precise and immediate feedback.
What is the difference between VO2max and threshold intervals?
VO2max intervals are performed at 106-120% FTP for 3-8 minutes, targeting maximum oxygen uptake. Threshold intervals are performed at 95-105% FTP for 8-30 minutes, improving lactate clearance and sustainable power.