4 Intervals

400m Run
1200m BikeErg
400m Run

– Rest 2:00 between intervals –

Overview. This session introduces the run–bike–run progression for this block. The aim of the progression is to improve your ability to run under fatigue and transition to running from other modalities. The focus today is on smooth transitions and consistent pacing. You’ll get to practice holding form and rhythm on the runs, coming off the bike.
Intent. Develop consistency in pacing between the first and second run of each interval, while learning to control BikeErg output so it doesn’t compromise your ability to run. The goal is repeatable execution across all four sets.
Effort. Run at 3-5k pace, keeping both 400m runs within a few seconds of each other. The BikeErg should feel controlled, around 85–90% of threshold, with a smooth cadence. The two-minute rest is enough to reset but not to fully recover = disciplined pacing is key.
Feel. Expect the first 50–100m of each run to feel heavy from the bike before your stride settles. Breathing will be strong but controlled, with a steady burn in the legs that remains consistent across sets. The intervals should feel demanding but repeatable.
Adaptation. Improve blood flow redistribution when shifting from bike to run, reinforce efficient run mechanics under fatigue, and build the ability to sustain even pacing across repeated transitions. Establish a base for the longer intervals in coming weeks.
Debrief. Take 2–3 minutes after the workout to reflect
– Were your 400m run splits consistent across all four sets?
– Did the second run match the first in each interval?
– Was your BikeErg pace and cadence stable from start to finish?
– Did the two-minute rest feel sufficient, or did you begin to slow down?
Movement options. This session’s intent is to work on your running so ideally don’t swap that out. You could use a different machine instead of bike erg if you must.