If you wear a smartwatch or fitness ring, you’ve probably experienced this: about a week before your period, your wearable gives you a terrible recovery score. It warns that your Heart Rate Variability (HRV) has tanked, your resting heart rate is up, and you need to “take it easy”—even if you slept fine and feel completely okay.

Sports scientist Dr. Stacy Sims exposes a glaring flaw in modern fitness tech: almost all wearables are coded around male baseline physiology. They treat a woman’s body like a 24-hour clock that should stay flat every single day of the month.

The Progesterone Effect on Your Wearable

After you ovulate, your body enters the luteal phase and produces high levels of progesterone. Progesterone is a warming, thermogenic hormone that naturally shifts your baseline metrics:

• Core Temperature Rises: Your baseline body temp increases by 0.3°C to 0.5°C.

• Resting Heart Rate Increases: Your pulse naturally speeds up by a few beats per minute.

• Breathing Rate Accelerates: Progesterone stimulates your brain to breathe slightly faster.

Because Heart Rate Variability (HRV) measures the subtle variation between heartbeats, these progesterone-driven shifts naturally lower your HRV. It’s not a sign that you are sick, out of shape, or failing your recovery—it’s proof that your progesterone is doing its job!

The Danger of “Red Recovery Scores”

Dr. Sims points out the psychological trap: when a woman sees a “red recovery score” on her app, she assumes her body is crashing. This triggers stress and self-doubt. To evaluate female data accurately, you cannot compare a Tuesday before your period to a Tuesday right after your period. You must compare luteal phase data to luteal phase data, and follicular data to follicular data.

How Pace & Phase Fixes Your Data

Pace & Phase was built specifically to eliminate male-biased tech algorithms:

• Physiology-Aware Analytics: The app interprets your daily biometrics (temperature, HRV, resting heart rate) through the lens of your specific cycle phase, so you never get shamed by an algorithm for natural progesterone shifts.

• Who It’s For: Anyone using Apple Health, Oura, Whoop, or fitness trackers who is tired of confusing recovery scores and wants actual context for their biometrics.

• True Readiness Score: It gives you an accurate picture of your capacity, telling you when to push for PRs and when your body is simply asking for active recovery.

Key Takeaway

Your body is not a static 24-hour clock. A drop in HRV before your period is a natural biological response to progesterone, not a health failure. Stop letting male-designed tech dictate how you feel, and start reading your data through a female lens.

Photo by April Laugh