Dear WHOOP Team,
Thank you for your ongoing efforts to improve training through data-driven insights. As a relatively new user, I appreciate the depth of your analytics and the ambition behind your platform.
However, I’d like to share some constructive feedback regarding the recommendations for time spent in heart rate zones 4 and 5, especially in the context of mixed training that includes both running and strength work.
1. Percentage-Based Targets: Unrealistic at Higher Training Volumes
In weeks where I train around 1000 minutes, WHOOP recommends that 20% of that time (about 200 minute) should be spent in HR zones 4 and 5. This recommendation becomes increasingly unrealistic as overall training volume increases.
• Issue: The percentage-based approach scales linearly with total training time, without accounting for the nature of the activities involved.
• Risk: This can lead to excessive time spent in high-intensity zones, increasing the risk of overtraining, fatigue, and injury—especially if recovery metrics are not adequately integrated into the recommendation.
2. Mismatch Between Training Type and HR Zone Expectations
WHOOP appears to apply the same HR zone expectations across all training types. This creates a significant mismatch when combining endurance and strength training:
• Strength training typically does not elevate heart rate into zones 4 or 5 for sustained periods. Even zone 3 is reached only sporadically, depending on the structure of the workout and also because of the challenges of correct HR measurement during strength training exercises.
• Running, on the other hand, can more easily reach higher HR zones. As a result, the burden of fulfilling the 20% zone 4/5 target falls disproportionately on running sessions.
This leads to a situation where I would need to perform a large portion of my runs at very high intensities just to satisfy a global metric, something that is neither physiologically sound nor aligned with most training principles.
3. Suggestions for Improvement
To make WHOOP’s recommendations more actionable and aligned with real-world training practices, I suggest:
• Activity-specific HR zone goals: Tailor zone expectations based on the type of training (e.g., endurance vs. strength), rather than applying a uniform percentage.
• Adaptive intensity targets: Consider recovery status, training goals, and individual capacity when suggesting time in high-intensity zones.
• Overtraining safeguards: Introduce alerts or guidance when users are trending toward excessive time in zones 4/5, especially in consecutive sessions.
I hope this feedback helps refine WHOOP’s approach and better support athletes who train across multiple disciplines.