Indoor Brick Session: 45-Minute Turbo + 20-Minute Treadmill Run

Session Overview

This indoor brick session combines a 45-minute turbo trainer ride with a 20-minute treadmill run, training the physiological transition between cycling and running without requiring outdoor conditions. It is ideal for early morning or winter training blocks, and for beginners learning to manage the heavy-legged sensation of running off the bike for the first time — the most distinctive physical challenge of triathlon.

What You’ll Need

• Turbo trainer or smart trainer with bike
• Treadmill (at the same gym, or at home)
• Running shoes laid out and ready before you start cycling
• Water and small towel
• Heart rate monitor (optional but useful for pacing both segments)

Warm-Up (10 minutes)

Start on the turbo trainer at an easy cadence (90-95 rpm) with minimal resistance. Spend the first 10 minutes simply spinning and allowing your heart rate to rise gradually. This is your warm-up — do not stretch before cycling.

Main Set

35 minutes of cycling at a moderate effort (Zone 2-3, RPE 5-7/10), followed immediately by 20 minutes of running on the treadmill. The transition between bike and run should be as fast as possible — change shoes and start the treadmill within 60-90 seconds of stopping the bike.

• Minutes 10-45: Turbo at Zone 2-3 — optional: add 3×2-minute Zone 3 efforts in the final 15 minutes if feeling strong
• Transition: change shoes quickly — no dawdling
• Run minutes 0-5: Easy pace as your legs adjust — expect them to feel heavy and unresponsive
• Run minutes 5-20: Build to a comfortable Zone 2 run pace and hold it

Cool-Down (5 minutes)

Reduce treadmill speed for the final 5 minutes to an easy walk, then complete 5 minutes of static stretching focusing on quads, hip flexors, and calves — all heavily loaded during this combined session.

Coaching Notes

• The first 5 minutes of running will feel wrong — your legs will feel heavy, your stride will be shorter than normal, and your pace will be slower than expected. This is entirely normal and is exactly what this session trains you to manage.
• Do not start the run too fast. Trying to force pace when legs feel brick-like leads to poor form and early fade. Trust the process and let the legs settle over the first few minutes.
• Beginner: keep the run effort at whatever feels sustainable; intermediate as written; advanced: increase bike effort to Zone 3-4 and run at Zone 3 pace.
• Consistency with this session is more valuable than maximum effort in any single session. Do it monthly through your build phase and the bike-to-run adaptation becomes automatic by race day.