An activity tracker involves the practice of measuring and collecting data on an individual's physical and psychological activity to keep track and maintain documentation regarding their health and wellness.[1] Used for many groups even animals as seen in collar-mounted activity trackers for dogs.[2][3][4] A lot of the data is collected through wearable technology such as wristbands which sync with mobile apps through Apple and Samsung. As daily technologies such as phones and computers have been innovated, it paved the way for such wearable tracking technologies to be advanced. There are a variety of stakeholders involved in the usage of activity tracking through wearable technology and mobile health apps, knowing how much they track ranging from fitness, mood, sleep, water intake, medicine usage, sexual activity, menstruation, and potential diseases raises the concern on privacy given a lot of data is collected and analyzed.[5] Through many studies that have been reviewed, data on the various demographics and goals these technologies are used provide more insight into their purposes.
The term "activity trackers" now primarily refers to wearable devices that monitor and record a person's fitness activity. 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.[6] The RS-Computer shoe was released in 1986. 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. Athletes are usually tracked with the levels of internal and external loads, where external loads will consist of the performance outcomes usually witnessed by coaches, and internal loads consist of factors such as heart rate, blood pressure, and blood lactate levels.[7] When taking into account the well-being of the subject, subjective scales are involved which measure fatigue, sleep quality, emotions, and soreness.[7] Physical movement tracking can be used as a predictive analysis tool to determine the risk of Parkinson's Disease in individuals.[8]
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.[9] Some also include a silent alarm.[9][10] 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.[11]
Smart Watches and Wristbands
Wristbands have since diversified to include wristbands and armbands (smart bands) and smaller devices that can be clipped wherever preferred.[10][12] Apple and Nike together developed the Nike+iPod, a sensor-equipped shoe that worked with an iPod Nano.
The Apple Watch and some other smartwatches offer fitness tracker functions.[11] In the US, BodyMedia has developed a disposable activity tracker to be worn for a week, which is aimed at medical and insurance providers and employers seeking to measure employees' fitness,[13] and Jawbone's UP for Groups aggregates and anonymizes data from the company's wearable activity trackers and apps for employers.[14] Other activity trackers are intended to monitor vital signs in the elderly, epileptics, and people with sleep disorders and alert a caregiver to a problem.[11]
Earbuds and headphones are a better location for measuring some data, including core body temperature; Valencell has developed sensor technology for new activity trackers that take their readings at the ear rather than the wrist, arm, or waist.[15] Numerous companies have also released devices in the form of a ring that leverages the capillaries in the finger.[16]
Activity Tracking Apps
In addition, logging apps exist for smartphones and Facebook;[17] the Nike+ system now works without the shoe sensor, through the GPS unit in the phone. Much of the appeal of activity trackers that makes them effective tools in increasing personal fitness comes from their making it into a game and from the social dimension of sharing via social media and resulting rivalry.[18]
The standard activity-tracking smartphone or web apps present data in statistical form meant to be viewed after the activity has ended. However, research suggests that if we want a richer understanding of the data, we need intelligent computing to be included in the systems that run the apps.[19]
There is also research problematizing tracking devices about how we inhabit, experience, and imagine our bodies and lives.[20] In 2016, there were several advances made regarding fitness tracking geared toward kids with a variety of options from organizations such as UNICEF and Garmin.[21]
Wearable sensors have been widely used in medical sciences, sports, and security. Wearable sensors can detect abnormal and unforeseen situations, and monitor physiological parameters and symptoms through these trackers. This technology has transformed healthcare by allowing continuous monitoring of patients without hospitalization. Medical monitoring of a patient's body temperature, heart rate, heart rate variability,[22] brain activity, muscle motion, and other critical data can be delivered through these trackers. Moreover, in sports training, there is an increasing demand for wearable sensors. For example, measurement of sweat rate was possible only in laboratory-based systems a few years ago but is now possible using wearable sensors.[23] Heart rate variability (HRV) has the potential to determine the quality of an exercise regimen. Additionally, HRV is recommended among the athletic community as a warning sign for over-training. In these ways, HRV can be used to optimize performance.[22] Wearable sensors play a pivotal role in monitoring physiological parameters and enhancing fitness regimens through AI-driven feedback and the development of intelligent equipment. This is evident in collaborative efforts between leading sports brands and technology companies.[24]
Certain movements of the user can distort the results obtained from activity trackers as seen in a test conducted by Stiftung Warentest where the products were unable to accurately track a bike ride.[25] Furthermore, the determined values for the human energy transformation were erroneous.[25] With the heart rate large deviations have been observed at wristlet trackers, and it is recommended for this purpose to use appropriate chest straps.[25]
Wristbands can be uncomfortable to wear and inadvertently be lost. For some products, genotoxic substances were detected.[25]
There have been some privacy issues regarding the data collection of activity-tracking apps, a user's health can be tracked into a "digital health footprint".[26] There have been many concerns about privacy issues with menstruation and reproductive health-tracking apps.[27] Many women who use these apps for menstrual and contraceptive tracking are under the impression that their data is private when there is no single body regulating the apps, making the availability and protection of the data unknown.[27] The apps of some activity trackers not only transmit personal data but also private address lists to servers on the Internet without notifying or asking the user.[25] Even when anonymized, the mere presence of geolocation data may be a national security risk.[28] However, the results of a study among semi-professional (half-) marathon participants suggest that certain users are open to sharing tracked activity data voluntarily.[29]
There has also been some research done on the "gamification" of health apps where users would be able to earn incentives and rewards based on their health goals.[30] Though this would make the app engaging, there was concern to whether or not this would trivialize the health apps and deter the users away from their genuine health goals.[30]
Heart Problems
Activity tracking has been utilized to keep track of heart problems, one of them being atrial fibrillation (AF) which causes an irregular and chaotic heartbeat and is accountable for a majority of strokes in the United States.[31] Professionals would rely on the ambulatory electrocardiogram (EKG) to record AF but soon found wearable wristbands to be useful for regular usage.[31] These wearables must be accurate to prevent misdiagnosis, morbidity, and mortality.[31] The Apple Watch was used for this study where it was able to have irregular pulse detection and send a notification once found.[31] Though there is a risk of false positives, it was found that it may be a useful tool in the initial diagnosis process as a gateway to additional procedures rather than being the only tool used.[31]
Weight Loss/Obesity
Activity trackers have also been used for tracking and finding solutions to combat obesity by promoting physical activity.[32] A device called the Fitbit Alta was used as the wristband for adolescents who are considered obese where their steps, distance, calories burned, activity time, and sleep rates were kept track of and downloaded by the researchers to analyze.[32] The overall study found that societal and cultural factors were what affected adolescent obesity given that low-income minorities were at a higher risk given that they had limited access to weight management programs and resources.[32] The tracking of steps and amount of physical activity allowed for one to be aware of their habits and lifestyle, but the access to weight loss programs varied for many, which is why the researchers utilized this information and used the technology to correlate behavioral aspects with the data to search for more solutions.[32]
One review of six studies found that there was little evidence that activity trackers improve health outcomes.[33] Of five studies that looked at weight loss, one found benefit, one found harm, and three found no effect.[33] Another systematic review covering 35 studies and 7454 participants, published in the British Journal of Sports Medicine, found that activity trackers increased people's physical activity by an average of 1850 steps/day.[34]
Monitoring Stress and Mental Illness
There are many apps available in the Apple AppStore and the Samsung Google Play Store that deal with mental health management and self-help.[35] Smartwatches have also been involved in monitoring stress and other mental health issues.[36] A study was done analyzing the different types of devices, ranging from bulky wearables to smaller, portable devices with sensors that can detect depression, anxiety, and any form of stress.[36] Monitoring these main three factors is essential to understanding any risk and likelihood of additional health complications and the correlation to specific conditions.[36] Chest patches are used for measuring heart rate while the wristbands ("Chillbands") were used to track activity, where a correlation was seen in the HR levels and the involvement of circadian rhythm, stress, gender, and age.[36] It was seen that detecting depression alone was challenging, causing a risk of misdiagnosis, but further research along with tracking of sleep, physical activity, mood changes, cognitive function, and social habits will help towards accurate measurements.[36]
Monitoring Infant Growth Development
According to another study comparing 8-week interventions and four-month follow-ups of physical activity monitors, a guided weight loss program, and together, activity monitoring and the weight loss program are associated with similar improvements and both combined are associated with more improvements than either alone.[33]
It is unclear whether activity changes occur in children and adolescents.[34][37] Wearable sensors have also been in use when keeping track of infant development, motor skills, and physical growth are the main aspects that were focused on.[38]
Menstrual Tracking/ Reproductive Health
Individuals with a uterus can use menstrual tracking apps to keep track of their cycles and refer back to the timeline to spot any changes that they would like to bring up to their doctors or specialists.[27] There are several apps for this purpose but the privacy and security of the data are unknown given that there is no one "head" that oversees the system, leaving a lot of the data open to the market, leaving many questions as to how secure the data is when entered.[27] When users sign up for these apps, they are usually led with an "at your own risk" warning in case any data gets leaked, which can contribute to more targeted ads and inaccurate predictions in their cycles.[27]
