Short answer: similar, but not the same — and the difference matters.
AeT (Aerobic Threshold) and VT1 (Ventilatory Threshold 1) describe roughly the same physiological transition, but they're measured differently and come from different testing protocols. Because of that, the numbers you get from each method won't always line up.
In REN, your training is built around three key metrics:
- AeT — the pace we use to optimize your endurance runs
- Critical Pace — your sustainable high-intensity pace
- VO2max Pace — your pace at maximal aerobic capacity
All of our workouts are calibrated to these specific metrics. If you swap in thresholds from a different test or training system (like a lab-measured VT1, a different app's lactate threshold, or a heart rate zone from another method), you'll end up with a training system that's out of balance — some sessions too hard, others too easy, and the overall stimulus no longer matching what the plan is designed to deliver.
The bottom line: don't mix and match definitions, tests, or training systems. Each system is internally consistent, but combining them breaks the logic. Stick with REN's metrics for REN workouts, and you'll get the progression the plan is built for.