REN uses three key thresholds to personalize your training: Critical Speed (CS), VO2max pace, and Aerobic Threshold (AeT). These thresholds have physiological relationships that must remain consistent. When you update or test one threshold, REN may automatically adjust the others to maintain realistic training zones.
The Relationship Between Your Thresholds
Critical Speed (CS): Your lactate threshold pace—the foundation of your training zones
VO2max pace: Your maximum aerobic capacity pace—faster than CS
Aerobic Threshold (AeT): Your easy-to-moderate pace—slower than CS
Initial Settings
Critical Speed is initially calculated based on the personal records (PRs) you enter during onboarding. This gives REN a starting point based on your actual race performances.
When you complete onboarding, REN then sets:
- VO2max pace = CS - 30 seconds per km
- Aerobic Threshold = CS + 35 seconds per km
These are starting points that adjust as you train and test.
How VO2max Pace and CS Stay Synchronized
VO2max pace is always faster than Critical Speed. When one changes, the other may need to adjust.
Automatic Adjustments
Rule 1: VO2max pace cannot be slower than CS
- This is physiologically impossible
- If you try to set VO2max slower than CS, REN will prevent this
Rule 2: When VO2max pace gets too close to CS (within 10 seconds)
- REN moves CS closer to VO2max pace
- This maintains a realistic gap between these two intensities
Rule 3: When VO2max pace is more than 45 seconds faster than CS
- REN moves CS faster as well
- This prevents an unrealistically large gap between thresholds
Why This Matters
If your VO2max pace improves significantly through testing, it's a strong signal that your CS has also improved. These thresholds don't exist in isolation—they reflect your overall fitness level.
How AeT and CS Stay Synchronized
Aerobic Threshold is always slower than Critical Speed. The ideal range is CS+30 to CS+50.
The Preferred Range
- CS + 30 seconds = RPE 7 (upper limit of AeT)
- CS + 35 seconds = Starting AeT setting
- AeT + 5 seconds = Where AeT intervals are prescribed (RPE 6)
- CS + 50 seconds = RPE 5 (lower limit of AeT)
Automatic Adjustments
Rule 1: AeT cannot be faster than CS
- This is physiologically impossible
- If you try to set AeT faster than CS, REN will prevent this
Rule 2: When AeT gets too close to CS (within 30 seconds)
- REN moves CS slower to maintain a realistic gap
- This prevents your easy pace from being too close to threshold
Rule 3: When AeT is more than 45 seconds slower than CS
- REN moves CS accordingly to close the gap
- This prevents an unrealistically slow aerobic threshold
Rule 4: When improved CS makes the gap to AeT larger than 45 seconds
- REN improves your AeT as well
- Maximum gap maintained at CS + 45 seconds
- Your improved fitness is reflected across all zones
Rule 5: When deteriorated CS makes the gap to AeT smaller than 30 seconds
- REN lowers your AeT accordingly
- Minimum gap maintained at CS + 30 seconds
- Ensures your easy pace remains physiologically appropriate
What This Means for You
You don't need to manually adjust multiple thresholds
- REN does this automatically to maintain consistency
- Focus on executing your tests properly
Your training zones stay realistic
- Thresholds can't drift into impossible ranges
- Improvements in one area trigger appropriate adjustments in others
Trust the system
- These relationships are based on exercise physiology
- REN ensures your training prescription remains effective and safe
The Bottom Line
Your thresholds are interconnected. When you test one, REN intelligently adjusts the others to reflect your true fitness level. This automation ensures your training zones remain accurate, realistic, and effective throughout your training cycle.
If you notice threshold adjustments after a performance test, this is REN working as designed—keeping all your training zones synchronized with your current capabilities.