Massachusetts wearables company Whoop is defying an FDA warning that its blood-pressure insights feature should be treated as a medical device.

It introduced the feature to help users see how their blood pressure relates to sleep, stress, recovery and exercise. It can be a critical indicator of how the wearer feels and performs, but has been hard to measure consistently or easily.

Whoop this month received notice from the US Food & Drug Administration (FDA) asserting that blood-pressure insights should be reviewed as a medical device before being available in the USA.

“We respectfully disagree,” says the Whoop response. “Blood-pressure insights is a wellness feature, not a medical device. It’s designed to help you understand how your body responds to daily life, not to diagnose or treat any condition. Wellness features like this are common in wearable technology, like tracking your respiratory rate or HRV, and provide valuable insights to support better decisions about your performance without requiring FDA clearance.”

The response goes on to say the company has always supported responsible regulation and was proud to receive FDA (www.fda.gov) clearance for its ECG feature.

“But we also believe it’s critical to protect access to wellness innovation, especially when wellness tools and features help people make smarter, more informed decisions to reach their full potential,” it says.

How blood-pressure insights work is that after a one-time calibration with a standard blood-pressure cuff during setup, Whoop uses the wearer’s heart rate, HRV and blood flow patterns during sleep to estimate blood pressure each morning when the body is rested and results are most accurate. Users see the usual two numbers representing systolic pressure when the heart beats and diastolic pressure when the heart rests. These readings can help users understand how their body responds to increased training loads, poor sleep and stressful days.

Whoop (www.whoop.com) trained its model using more than 32,000 sleep sessions from 11,000 members, then validated the results against clinical readings.

“We stand by its accuracy, which the FDA has not questioned,” says the statement.

Blood pressure acts like a mirror. It reflects how the body responds to everything from exercise to life stress to recovery demands. Research shows that blood pressure plays an essential role in hydration. Paired with heart rate, blood pressure can indicate dehydration after exercise, helping guide fluid and electrolyte replacement.

For stress and recovery, higher blood pressure overnight can signal that the body hasn’t fully recovered from physical or emotional stress, and may be especially informative about post acute increases in training load.

“Over time, learning about your blood pressure can help you make smarter decisions to optimise how you feel and perform,” says the statement (www.whoop.com/us/en/thelocker/why-whoop-stands-behind-blood-pressure-insights).

The feature was introduced to help users track how their body responds to life’s demands, understand how lifestyle habits impact recovery, stay ahead of stress, dehydration and fatigue, and make smarter, more confident decisions.

“This is a feature designed to empower you,” says the statement. “As always, we encourage you to speak with healthcare providers for any clinical concerns. Whoop is proud of this innovation, and we’ll keep building tools that help you take charge of your performance, recovery and long-term health.”

The company later added: “Recent FDA statements asserting blood-pressure insights must be reviewed as a medical device fail to acknowledge the fact that the feature is a wellness tool not intended to diagnose or treat any medical condition. This interpretation is also inconsistent with the 21st Century Cures Act, which clarifies that functions intended to promote a healthy lifestyle – and unrelated to the diagnosis, cure, mitigation, prevention or treatment of a disease or condition – are excluded from the definition of a medical device.”

The firm says it created blood-pressure insights on a foundation of rigorous data validation and peer-reviewed research to provide members information about their bodies and help unlock performance. Members are clearly informed through onboarding and in-app disclaimers that blood-pressure insights is not intended for medical decisions or as a substitute for clinical-grade monitors for diagnosing or treating clinical conditions.

“Whoop members have long been at the forefront of using data to improve performance,” it says. “Heart rate, HRV, recovery score, stress score, respiratory rate and many other metrics are used by Americans to better understand their wellness and improve their performance. Blood-pressure insights continue that tradition. Our members are already finding ways to live and train better. We stand by blood-pressure insights and believe our members should be able to access data about their bodies.”