Over-Under Turbo Intervals: Advanced FTP Builder

Session Overview

Over-under turbo intervals are one of the most effective ways to raise your FTP and build top-end cycling endurance for triathlon. This 60-minute session alternates between efforts just below your FTP (the “under”) and pushes above it (the “over”), training your body to clear lactate more efficiently under race conditions. Best suited to advanced cyclists with a current FTP figure.

What You’ll Need

• Turbo trainer (smart trainer recommended for accurate power control)
• Power meter or smart trainer power output
• Heart rate monitor (optional but useful)
• Fan — this session generates serious heat output
• Water bottle — at minimum 750ml for this session

Warm-Up (10 minutes)

Spin at 55–65% FTP for 8 minutes to get blood flowing. Then ride 2 x 30 seconds at 100% FTP (your target power) with 1 minute easy spinning between. This primes your neuromuscular system and confirms your power targets feel right before the main set begins.

Main Set (40 minutes)

Complete 4 rounds of the following over-under block. Each round is 8 minutes: alternate between 85–90% FTP (under) and 105–110% FTP (over) in the structure below. Rest 3 minutes easy spinning at 55% FTP between each round.

• Round structure (8 minutes): 2 min at 88% FTP (under) → 1 min at 108% FTP (over) → 2 min at 88% FTP → 1 min at 108% FTP → 2 min at 88% FTP
• Recovery: 3 minutes at 55% FTP between each of the 4 rounds
• Total work: 4 × 8 minutes = 32 minutes of over-under work, 9 minutes recovery

Cool-Down (10 minutes)

Spin at 50–55% FTP for 10 minutes. Keep cadence high (90+ rpm) to flush lactate and bring your heart rate back down before dismounting. Stretch quads, hamstrings, and hip flexors after dismounting.

Coaching Notes

• Your FTP should be based on a recent 20-minute power test (multiply average power by 0.95) or a ramp test
• If you can’t sustain the “over” efforts by round 3 or 4, reduce to 103–105% FTP — don’t sacrifice form for numbers
• Easier version: reduce to 3 rounds instead of 4, or shorten over efforts to 45 seconds
• This session is best performed 48 hours before a rest day — recovery is crucial afterwards
• Target HR during “over” efforts: Z4/Z5 (typically 85–95% max HR)