Turbo Sweetspot to Threshold Progression: 75-Minute Indoor Power Build

Session Overview

This 75-minute turbo trainer session combines sweetspot and threshold efforts in a progressive structure — starting manageable and building to your lactate threshold by the end. It’s one of the most time-efficient ways to build FTP and aerobic power, and it suits intermediate to advanced triathletes who have at least two indoor sessions per week in their programme.

What You’ll Need

• Turbo trainer or smart bike (power meter recommended)
• Heart rate monitor
• Fan for cooling
• Water bottles — aim to drink 500-750ml per hour during this session
• Electrolyte tabs or sports drink (optional)

Warm-Up (15 minutes)

Spin easily at 90+ RPM for 10 minutes at Zone 1 to 2 effort (RPE 4-5/10, 55-65% FTP). In the final 5 minutes, include 3 x 30-second efforts at 90% FTP with 1 minute easy spinning between them. These openers prime the neuromuscular system and prepare the legs for the main set.

Main Set

The main set progresses from sweetspot efforts (88-93% FTP) toward threshold (95-100% FTP). Each block increases in intensity while keeping the work intervals long enough to drive genuine aerobic adaptation. Cadence target throughout is 85-95 RPM.

• Block 1: 12 minutes at sweetspot (88-93% FTP / RPE 7/10). 4 minutes easy recovery.
• Block 2: 10 minutes at sweetspot building to low threshold (92-95% FTP / RPE 7.5/10). 3 minutes easy recovery.
• Block 3: 8 minutes at threshold (95-100% FTP / RPE 8/10). 3 minutes easy recovery.
• Block 4: 6 minutes at threshold (100% FTP / RPE 8.5/10). End of main set.

Cool-Down (10 minutes)

Spin very gently at 55-60% FTP for 10 minutes to flush lactic acid and bring heart rate down progressively. Do not stop abruptly after threshold efforts — your body needs this transition to recover properly. Stretch quads, hamstrings, and hip flexors off the bike.

Coaching Notes

• Without a power meter, use RPE and heart rate: sweetspot should feel ‘comfortably hard’ — you can speak in short sentences; threshold should feel ‘hard’ — only a few words possible
• If you don’t know your FTP, a 20-minute all-out test (95% of average power) gives a good estimate
• Do this session twice weekly for 4 weeks for significant FTP gains
• Beginners: shorten each block by 2 minutes and extend the recovery periods
• If you crack on Block 3 or 4, hold your best sustainable power — don’t stop, just dial it down slightly