Measuring Stress & Recovery
Stress is a natural part of everyday life and contributes to the healthy and balanced overall condition of an individual. The Stress & Recovery values provided by the SmartBand 2 refer to a combination of your Heart Rate (HR) and Heart Rate Variability (HRV). SmartBand 2 analyses your Heart Rate Variability (HRV) and assesses how well your body manages stress levels during different situations throughout the day.
The SmartBand 2 can measure Heart Rate (HR) and Heart Rate Variability (HRV) even if the device is disconnected from an Android™ device. Data collected using the heart rate sensor is stored for up to 72 hours and synced to the Android™ device once connected via Bluetooth or NFC.
This product is intended to help you track your exercise and lifestyle. It is not a medical device and data from it should never be used to make medical decisions (like preventing, diagnosing, monitoring, or treating a disease or injury) or replace the advice of a medical professional. Sony Mobile disclaims any warranty that this device could be used or suitable for medical purposes. Seek medical advice before undertaking a new or altered training regime using this device, particularly if using this device together with a pacemaker or other medical devices.
Extensive use of pulse and stress measurement increases battery consumption.
Pulse measurement is the generally recommended method of determining your heart rate (HR), which can be a rough indicator of intensity of exercise. Pulse rate is expressed by the number of times your heart beats per minute (BPM). Although "pulse rate" and "heart rate" are two different concepts, the terms are used in the same context in this User guide.
Stress and recovery levels
Stress & Recovery is determined using Heart Rate Variability (HRV). The heart rate is never constant and the time difference between two consecutive heartbeats changes from beat to beat. This variation is called Heart Rate Variability (HRV). If the variation in-between heartbeats is high, this indicates a relaxed or recovering state. If the variation is low, this indicates stress.
Activities such as reading a book may result in low stress levels, or can even be tracked as recovery. For example, busy moments at work or school may result in a high stress indication. It is important to note that a stress reaction does not have to be negative; it may also indicate that you are experiencing something exciting or fun. To balance periods of high stress, you need to recover by relaxing and sleeping well. A medium stress level may indicate effortless productivity, which is common during work and social activities.
Recovery mostly occurs while you sleep. There are factors that can affect your recovery measurements. A physically active lifestyle, healthy nutrition, lower consumption of alcohol, and elimination of stress factors make it possible to improve recovery during sleep in the long run. Avoiding highly strenuous physical activities and "slowing down" mental activities well before going to bed also have a positive effect on recovery.
Stress & Recovery values provided by the SmartBand 2 are not a reliable source for analysing overall fitness. Low intensity exercises, for example, can be misinterpreted incorrectly as recovery.
To get an measurement of your Stress & Recovery, wear your SmartBand 2 for at least one night when you go to bed.
How the SmartBand 2 measures your pulse and stress
The SmartBand 2 uses green lights paired with light-sensitive photodiodes to detect the amount of blood flowing through your wrist at any given moment. By flashing its lights hundreds of times per second, the SmartBand 2 can calculate the number of times the heart beats each minute and provide an estimate of your heart rate.
Factors that affect pulse and stress measurement
Several factors can affect the performance of the SmartBand 2 heart rate sensor.
- Skin perfusion: the amount of blood flowing through the skin varies significantly from person to person and can also be impacted by the environment. If you’re exercising in the cold, for example, the skin perfusion in your wrist may be too low for the heart rate sensor to get a result.
- Movement: rhythmic movements such as running or cycling give better results from the heart rate sensor compared with irregular movements like in tennis or boxing.
- Skin pigmentation variations: permanent or temporary changes to your skin, such as some tattoos. The ink, pattern, and saturation of some tattoos can block light from the sensor, making it difficult to get reliable results.
Getting the most from the SmartBand 2 heart rate sensor
Even under ideal conditions, the SmartBand 2 may not be able to get a reliable heart rate reading every time for every individual. For a small percentage of users, various factors may make it impossible to get any heart rate reading at all. Perform the following steps if you want to improve the reading from the heart rate sensor:
- Make sure that you wear your SmartBand 2 snugly, but comfortably on your wrist. If it does not stay in place on your wrist and the heart rate sensor fails to get a good reading, tighten the wristband.
- You may need to clean the SmartBand 2, especially the heart rate sensor, after exercising or heavy sweating.
Measuring pulse and stress automatically
The SmartBand 2 measures your pulse and stress and recovery level about six times an hour.
Measuring pulse and stress manually
You can have your SmartBand 2 perform a reading of your pulse at any time, either from the device itself or from your Android™ device.
To get the best heart rate data when exercising, initiate the heart rate sensor a few minutes before your physical activity so that the sensor is able to detect your pulse.
Notifications, except for incoming calls and alarms, are not passed to your SmartBand 2 when you measure your pulse and stress manually.
To measure your pulse and stress manually from your SmartBand 2
- To start measuring your pulse and stress level, double-press the power key. The notification lights start to flash orange alternately and then together when the reading is complete. The results are then displayed on the SmartBand 2 application on your iPhone.
- To end the measurement, double-press the power key again.
If the SmartBand 2 cannot detect your pulse, it vibrates three times and the notification lights start to flash alternately in orange. If the heart rate sensor fails to get a reading, adjust the SmartBand 2's position on your wrist or clean the sensor. For more information on improving the reading from the heart rate sensor, see Getting the most from the SmartBand 2 heart rate sensor.
To measure your pulse and stress manually from your Android™ device
- From the main application screen of your Android™ device, find and tap SmartBand 2. The SmartBand 2 immediately attempts to get a reading from the heart rate sensor and displays the results on the Lifelog or SmartBand 2 application.
- To end the measurement, quit the SmartBand 2 application.