Optical sensors in the WHOOP 4.0 band continually record your heart rate, heart rate variation, blood oxygenation, breathing rate and skin temperature.

Photoplethysmography (PPG) The Technology WHOOP measures blood flow using a technology called Photoplethysmography (PPG). There are LEDs (light-emitting diodes) on the bottom of the strap that shine light into your skin, which is full of tiny capillaries. Blood in the capillaries absorbs more of the light than the tissue surrounding it.

The wearable WHOOP tracker is a two-in-one device that uses both fitness and sleep data. The goal is to calculate overall recovery, which WHOOP defines as how prepared you are for activities in the day ahead based on your recent exercise, heart rate, and how well you slept the previous night.

Whoop 4.0 tracks a number of things during sleep, including: The time you fell asleep, the time you woke up, exactly how much of that in-between time was asleep, sleep phases, your body temperature shifts, SpO2, breathing rate, and HRV values. Most of these things are then weighted and pulled into the sleep score.

WHOOP also measures your stress levels in real time to help you evaluate your stress in the moment, and provides scientifically validated breathwork protocols to help you manage it. WHOOP also monitors critical vital signs, including blood oxygen levels, heart rate, respiratory rate, and skin temperature.

Conclusion. Clearly, the Garmin is more accurate than the Whoop and paired with the Polar arm band, much more so.

Whoop claims the Strap 4 has four times the number of photodiodes used to measure physiological markers. These sensors monitor heart rate, respiration rate, skin temperature, blood oxygen saturation, heart rate variability, and heart rate reserve.

Whoop is an American-made wearable technology company, (unlike Fitbit, Apple, and most other wearable fitness trackers on the market which are typically made in China and Vietnam).

Enjoy your woodland retreat, backcountry hike, or that trip without service – with a Bluetooth connection, WHOOP will continue recording your data. Once your WHOOP is synced to your mobile device with cellular service or a WiFi connection, it will process the recorded data.

Calculating Muscular Load WHOOP has developed an algorithm to calculate muscular load – the amount of stress put on muscles, bones, joints, and tissues. Strength Trainer uses biomechanics to track the impact various strength training exercises have on your body.

SCIENCE-BACKED METRICS THAT MATTER WHOOP outperforms other leading wearables, delivering over 99% heart rate and HRV tracking accuracy and gold-standard sleep tracking, making it one of the most powerful, most accurate, and most wearable human performance tools you can buy.

Unlike other wearables, Whoop doesn't try to prescribe the details of your workouts or training plan. Instead, it fits in around your existing training regime to coach you on how well your body handled your workouts and adds in sleep guidance to optimize your performance for the next day.