Sport-Calculator.com

Sport-Calculator.com

Cycling Workout

4x8 Seiler Intervals

Research-backed 4x8 minute intervals at ~90-95% FTP. This protocol, studied by Seiler, showed superior adaptations compared to both shorter and longer intervals.

4x8 Seiler Intervals

wattsCalculate
Advanced
Warm up
8:00 @ 102-170W (56-80% FTP)
Main Set
0:30 @ 202-222W (106% FTP)
0:30 recovery @ 102-122W (56% FTP)
0:30 @ 210-230W (110% FTP)
1:00 recovery @ 102-122W (56% FTP)
1:00 @ 222-242W (116% FTP)
3:30 recovery @ 90-110W (50% FTP)
Repeat 3 times:
1. Hard: 8:00 @ 204-224W (107% FTP)
2. Easy: 3:00 @ 90-110W (50% FTP)
8:00 @ 204-224W (107% FTP)
Cool Down
2:00 @ 70-90W (40% FTP)
Total Duration: 64:00
Photo of Jonas

About the Author

I'm a software developer and cycling enthusiast from Germany with over 10 years of experience. I've personally tested and refined all these workouts over the past years, and I can confidently say they will help improve your cycling performance through structured training.

4x8 Seiler Intervals: The Research-Backed VO2 Max Protocol

The 4x8 minute interval protocol, popularized by exercise physiologist Stephen Seiler, represents a scientifically optimized approach to VO2 max development. This format has been extensively studied and shown to produce superior adaptations compared to both shorter and longer intervals.

Scientific Background

Professor Seiler's research has demonstrated that:

  • 8-minute intervals maximize time at VO2 max
  • 92% FTP represents the optimal intensity for these intervals
  • 4-minute recoveries allow for consistent performance across intervals
  • 4 repetitions provide the ideal balance of stimulus and fatigue

Workout Structure

The session follows this precise structure (total duration: 64 minutes):

1. Progressive Warm-up (15 minutes)

  • 8 minutes progressive from 56% to 80% FTP
  • 30 seconds at 106% FTP
  • 30 seconds recovery at 56% FTP
  • 30 seconds at 110% FTP
  • 1 minute recovery at 56% FTP
  • 1 minute at 116% FTP
  • 3:30 minutes recovery at 50% FTP

2. Main Set (44 minutes)

  • 4 repetitions of:
    • 8 minutes at 107% FTP (aim for 105 rpm on selected intervals)
    • 3 minutes recovery at 50% FTP

3. Cool-down (8 minutes)

  • 2 minutes very easy at 40% FTP
  • 6 minutes easy at 50% FTP

Key Features of This Workout

Structured Warm-up

  • Progressive intensity increase from 56% to 80% FTP
  • Short high-intensity bursts to prime the system
  • Strategic recovery periods between efforts

Main Intervals

  • Consistent 107% FTP intensity for all main intervals
  • Target cadence of 105 rpm for specific intervals
  • Adequate recovery periods to maintain quality

Recovery Strategy

  • 3-minute recoveries between main intervals
  • Low intensity (50% FTP) for optimal recovery
  • Two-stage cool-down for proper workout completion

Execution Guidelines

  • Maintain steady power output during intervals
  • Keep cadence in 85-95 rpm range
  • Focus on smooth, efficient pedaling
  • Stay aerobic - avoid going anaerobic
  • Use recovery intervals effectively

When to Use This Workout

This workout is particularly effective for:

  • Building base aerobic fitness
  • Preparing for time trials
  • Improving climbing ability
  • General endurance development
  • Breaking through VO2 max plateaus

Progression and Modifications

  • Beginner Version:
    • Reduce intensity to 88-90% FTP
    • Start with 3 repetitions
    • Extend recovery to 5 minutes if needed
  • Advanced Progression:
    • Increase to 94-95% FTP
    • Add a fifth interval
    • Reduce recovery to 3 minutes