Sony Ericsson SmartBand 2 User Guide - Page 10
Pulse measurement, Stress and recovery levels, How the SmartBand 2 measures your pulse and stress
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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 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 Many factors can affect the performance of the SmartBand 2 heart rate sensor: • Skin perfusion. Skin perfusion - how much blood flows through your 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 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. 10 This is an Internet version of this publication. © Print only for private use.