Fitness tracker

An activity tracker, also known as a fitness tracker, is a device or application for monitoring and tracking fitness-related metrics such as distance walked or run, calorie consumption, and in some cases heartbeat and quality of sleep. The term is now primarily used for smartwatches that are synced, in many cases wirelessly, to a computer or smartphone for long-term data tracking. There are also independent mobile and Facebook apps. Some evidence has found that the use of these type of devices results in less weight loss rather than more.

In those who are overweight or obese some evidence has found that the use of these type of devices results in less weight loss rather than more after two years of use. It is unclear if these devices affect the amount of physical activity children engage in.

The term "activity trackers" now primarily refers to wearable devices that monitor and record a person's fitness activity. The concept grew out of written logs that led to spreadsheet-style computer logs in which entries were made manually, such as that provided in the US by the President's Council on Physical Fitness and Sports as part of The President's Challenge. Improvements in technology in the late 20th and early 21st century allow automating the monitoring and recording of fitness activities and integrating them into more easily worn equipment. Early examples include wristwatch-sized bicycle computers that monitored speed, duration, distance, etc., available at least by the early 1990s. Wearable heart rate monitors for athletes were available in 1981. Wearable fitness tracking devices, including wireless heart rate monitoring that integrated with commercial-grade fitness equipment found in gyms, were available in consumer-grade electronics by at least the early 2000s.

Electronic activity trackers are fundamentally upgraded versions of pedometers; in addition to counting steps, they use accelerometers and altimeters to calculate mileage, graph overall physical activity, calculate calorie expenditure, and in some cases also monitor and graph heart rate and quality of sleep. Some also include a silent alarm. Some newer models approach the US definition of a Class II medical monitor, and some manufacturers hope to eventually make them capable of alerting to a medical problem, although FDA approval would be required. Early versions such as the original Fitbit (2009), were worn clipped to the waist; formats have since diversified to include wristbands and armbands (smart bands) and smaller devices that can be clipped wherever preferred.Apple and Nike together developed the Nike+iPod, a sensor-equipped shoe that worked with an iPod Nano.

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