Heart-Rate Load in Enduroco

Enduroco currently uses a threshold-ratio heart-rate fallback for both cycling and running:

• cycling.hrLoad
• running.hrLoad

Current Formula in Enduroco

• Cycling: round((averageHR / cyclingLTHR) * 100)
• Running: round((averageHR / runningLTHR) * 100)

This is a simple threshold-relative load score.

Relation to hrTSS and TRIMP

Industry heart-rate methods (for example TrainingPeaks hTSS/tTSS and Banister TRIMP families) usually include:

• Session duration
• Heart-rate intensity relative to threshold or HR reserve
• Non-linear weighting at higher intensities

So Enduroco’s current HR fallback is intentionally simple and interpretable, while broader hrTSS/TRIMP methods are more physiology-modeled.

When This Source Is Used

Heart-rate load is used when higher-priority power/pace sources are unavailable for that activity type.

References

• TrainingPeaks Help: Heart-rate-based TSS context (hTSS/tTSS)
• Banister TRIMP summary (peer-reviewed overview table)
• Intervals.icu forum: load estimated from heart rate when power is unavailable