Frequently Asked Questions

KuaiFit automatically sends heart rate data through ANT+ and Bluetooth Smart (BLE) during workouts and training. You can receive the data through virtually any phone fitness app, sport watch, bike computer, gym equipment or any other device that receives heart rate data by ANT+ or BLE.

KuaiFit also automatically receives speed, cadence and power data while cycling through ANT+. You can use any bike speed, cadence or power meter using ANT+ and your KuaiFit will automatically connect to it.

KuaiFit is the only multisport headphones in the world that uses clinically validated heart rate sensor technology.

In partnership with Duke University’s Center for Living, the performance of the biometrics used in KuaiFit was tested versus benchmark ECG and indirect calorimetry (measurement of heat produced by physical changes) sensors. The final result showed that the sensor technology used by Kuai measures heart rate and predicts energy expenditure accurately, with a low standard deviation for heart rate of ±4 percent and energy expenditure (or calories burned) of ±7 percent. Considering that the machine errors of the ECG and gas exchange analysis devices are within a standard deviation of ±3%, it has been determined that the technology is accurate when compared with clinical gold standards.

On top of that, in studies carried out by North Carolina Wesleyan College and Campbell University, 40 participants completed a dynamic protocol that included 15.5 minutes combining sitting, standing, walking and running on the treadmill using KuaiFit’s integrated biometric sensor technology. The results showed a significant positive correlation compared to twelve lead ECG, 95 percent of data points (74,440 total data points) were within the 95 percent confidence interval and a low standard deviation of ±4.43 percent with respect to ECG.

The ear is an ideal location for measuring vital parameters. The carotid artery system runs perpendicularly along the ear canal region and a capillary system runs across the antitragus and earlobe, providing access to blood flow and heart rate through PPG. On top and unlike wrist worn devices, the ear is well protected and provides a very stable position that does not move excessively during exercise, making it the perfect platform for physiological measurements.

No, KuaiFit are smart headphones with an integrated MCU and 8GB of memory, which means they can operate autonomously without the need to connect to a phone or any other device.

Yes, you can answer phone calls with KuaiFit when connected to phones via Bluetooth.

Yes, you can listen to music directly from your phone using KuaiFit, when connected via Bluetooth. Remember you can also upload your music to KuaiFit’s 8GB of memory so you do not need to be connected to your phone.

Free Training: Do your workouts and receive voice notifications based on your performance.

Training Plans: Download plans from professional coaches that guide you through the entire workout.

Listen to Music: Upload your music to the 8GB of memory or connect to your phone via Bluetooth.

During Free Training, you will hear instant notifications of your performance data (heart rate, speed, distance, cadence, calories, time, etc). You can set the data you hear and its frequency in your online KuaiFit account, or use default ones. Also at any point during training you can press on the controls on the Sport side to hear your current data.

Download training plans for different sports, goals and fitness levels, online at the www.kuai.fit store. After downloading plans to your computer simply connect your KuaiFit headset using the USB cable provided and open the KuaiFit Desktop Application. All of your downloaded plans will show up under ‘Available Training Plans’ and you only need to press the ‘Add’ button to upload the plans you wish to have on your KuaiFit headset.

Heart rate (HR) zones are used to set the intensity of training during the sessions.

HR zone 1; warm-up and cool-down (less than 60% effort).

HR zone 2; light exercise (60-70%).

HR zone 3; mild exercise (70-80%).

HR zone 4; hard exercise (80-90%).

HR zone 5; very high tempo only for very short periods (90-100%).

KuaiFit automatically records your workout data internally, but you can visualize your data in the following ways:

KuaiFit Web - You can view all of your data through your KuaiFit account. To upload data after a workout, connect KuaiFit to your computer using the USB cable, open up the KuaiFit Desktop Application, and your data will sync and show up in your KuaiFit account (under ‘Activities’).

KuaiFit App - If you work out connected to the KuaiFit app, your data will be automatically stored in the ‘History-Local’ section of the app. If you work out without connecting to the KuaiFit app, after synchronizing your headset with your computer, you will be able to see your workout data in the ‘History-Web’ section of the KuaiFit app.

KuaiFit .FIT - All your workout data is saved in both .FIT and .xlsx formats ready to be exported to any fitness app you wish.

Yes, all of your workout data is saved in both .FIT and .xlsx formats ready to be exported to any fitness app you wish. In your KuaiFit account you will see a button next to each recorded workout.

1. Sign up for a KuaiFit account at www.kuai.fit All of your workout data will be stored here.

2. Download the KuaiFit Desktop Application from: www.kuai.fit/download This is needed to upload music and sync training plans to your KuaiFit headphones.

3. Download the Phone app. It provides a visual display for your workouts.

iOS - Connect KuaiFit to your phone via Bluetooth, then begin your session on the headset. Open the app and press START.

Android - Turn on Bluetooth. Open the app and press START. Choose your KuaiFit device. Begin your session on the headset.

KuaiFit takes your personal data to provide an automatic calibration, however in order for KuaiFit to provide more accurate data, it needs to be tuned to your body and calibrated doing two very simple calibration tests:

Heart Rate Calibration: Lay down for 2 minutes.

Stride Calibration: Run 400m and walk 400m.

The optical infrared (IR) emitter shines infrared light on the region of the ear between the anti- tragus and concha. The vast majority of the light travels through the skin and never reaches the detector. Some light is absorbed by the skin and never reach the detector. Some light is reflected directly off the surface of the skin causing signal noise. A tiny amount of light will enter the tissue, be modulated by the blood flow, and scatter back out to the optical detector. This is the heart rate signal our sensors cleverly use to give you accurate data that is clinically validated by Duke University.

About KuaiFit


The world’s only multi-sport smart headphones that automatically measure your body and performance during any sport on land or in water, providing adaptive live voice coaching using patented technology, accurate sensors, and proprietary software algorithms. KUAIFIT connects to an online platform of training plans created by top coaches and Olympic athletes designed to help users achieve their fitness goals.

Contact Us


Kuaiwear Limited,

     A10 Wong’s Building,

     33 Hung To Road,

     Kowloon, Hong Kong

contact@kuaiwear.com