Aerobic Power Outdoor Ride: 3×15-Minute Zone 3 Blocks

Session Overview

This 75-minute outdoor ride builds sustained aerobic power through three 15-minute blocks at Zone 3 — the often-neglected training zone between easy endurance and threshold. Regular Zone 3 work raises your sustainable bike pace at Olympic and 70.3 distances without the recovery cost of full threshold sessions.

What You’ll Need

• Road bike or triathlon bike in good mechanical order
• Power meter or GPS watch with heart rate monitor
• Two full water bottles — you will need both
• Optional: cycling computer with real-time power or heart rate display

Warm-Up (15 minutes)

15 minutes easy Zone 1–2 at 85–95 rpm cadence. Use this time to find a suitable route — you want a manageable road with minimal sharp junctions so you can hold effort across the 15-minute blocks without interruption. Avoid busy roads during the main set.

Main Set

3 x 15 minutes at Zone 3: 75–85% FTP or RPE 6–7/10 — breathing noticeably elevated but you can still speak short sentences. Recovery: 5 minutes easy Zone 1 spinning between each block.

• Target cadence: 85–90 rpm — prioritise smooth power delivery over a grinding, low-cadence style
• Maintain aero position where safe — use these blocks to practise your race-day posture
• Heart rate will drift upward over 15 minutes even with steady power — this is cardiac drift, not a pacing failure
• Keep your power or RPE anchored to the first 5 minutes of each block, not the last

Cool-Down (10 minutes)

10 minutes easy Zone 1, progressively reducing cadence from 85 to 70 rpm. Stay topped up with water during this phase. Complete a short stretch sequence off the bike: hip flexors, hamstrings, calves.

Coaching Notes

• Zone 3 feels deceptively easy in the first 5 minutes but becomes taxing by minutes 10–15. Don’t push harder early — consistency across all three blocks is the goal.
• Scale down: reduce blocks to 10 minutes each, or extend recovery to 8 minutes between reps
• Scale up: extend each block to 20 minutes for a 70.3-specific aerobic stimulus — total session approximately 95 minutes
• Best used once a week in a build phase, replacing one of your easier endurance rides