Fast-Start Fours
75 min · 65-80 TSS · IF 0.75 · 105-130% FTP · Zone 5+ (VO2max)
What this workout does
Four-minute intervals that open with a 30-second surge. The hard start drives your oxygen uptake up fast, so you spend more of each rep at your aerobic ceiling - more stimulus from the same minutes.
The opening surge floods the muscles with demand, so oxygen uptake reaches its maximum in the first minute of each rep instead of the third. Fast-start pacing earns more time at high oxygen uptake per rep than even-paced efforts of the same length. Use it when you want maximum aerobic stimulus from limited interval time.
How to ride it
Indoor / trainer
Warm up 15min with 3 short openers. 5 reps: surge 30s at 120-130% FTP, then settle into 3min 30s at 105-110% FTP. 4min easy between. Cool down 15min.
Outside
Works on a steady climb or a flat road. Kick hard for the first 30s - above 120% FTP, breathing spikes immediately - then settle into 105-110% FTP for the rest of the rep and hold it to the line.
Workout structure (75 min)
- Warm-up 15m 55% 3x - Opener 30s 110% - 1m 30s 55% 5x - Surge 30s 125% - Hold 3m 30s 108% - 4m 55% - Cool-down 15m 55%
Targets are a percentage of FTP. This is the same shorthand the free workout builder understands — paste it there to edit any step, or download the workout for Zwift, Garmin or any smart trainer.
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