a lot of people are using fitness trackers nowadays you can track basic stuff like your steps your activity levels and your heart rate and you can track fancier stuff like your calories your oxygen levels and even your sleep patterns and you could be tracking this from a smart watch or a fitness band or even a smart ring but are these devices accurate and what does science tell us about their actual impact on our health let's get into it so fitness trackers come in many different shapes and styles but at their core they all do the same basic things they use a motion sensor to measure and quantify your movement like your steps and a heart rate monitor to measure your heart rate so the first question is do they actually measure these things accurately so trackers are pretty good at counting steps there have been lots of studies showing them to be almost as accurate as research grade pedometers which are those old school devices people used to wear on their hips no not pagers pedometers and who still wears a pager anyways [Music] that being said if you walk very slowly or have an unusual walking style they'll probably underestimate your steps but if you move your hands around a lot they will overestimate your steps but overall this is one of the things that trackers do best as for the next big one heart rate as a general rule trackers are very good at measuring your heart rate when you're resting but a little less accurate when you're exercising where they tend to underestimate it Studies have also shown lots of variability in the accuracy of different devices so it matters which device you choose either way overall it will give you a good idea of the general range of your heart rate and devices are getting more and more accurate the next big one is your energy expenditure or your calorie burn the weight trackers estimate this is by measuring the motion of your body and combining that with basic characteristics like your height weight sex and age to then estimate your calorie usage the problem there is that energy expenditure is complex and it relies on things like body composition or how much muscle versus fat you have and even if some sensors allow you to enter that info most people don't actually know their body fat percentage so in a review of 60 different studies most sensors were pretty inaccurate at calculating your calorie burn and they tend to underestimate it especially if you're doing exercises where you don't move your wrist a lot like cycling that being said some of the newer sensors are able to add heart rate and even heat sensing to the motion data and those ones are therefore more accurate the other measure that's really interesting to me as a lung doctor is blood oxygen level that's been around for a while but major players like Apple and Samsung only added this feature in 2020. since then there have been a handful of studies looking at accuracy and when they compare them to these pulse oximeters that we typically use to measure oxygen levels SmartWatches actually did pretty well the difference in readings was within about three percent now most companies aren't accurate enough to have FDA clearance to use as a medical device but it can be very helpful for people with lung conditions for example to monitor whether their oxygen levels are improving with treatment on the other hand for patients with covid-19 where we often do recommend monitoring oxygen levels at home with one of these pulse oximeters that three percent difference could be very misleading in either direction so they're not quite accurate enough for that so let's assume that you are getting pretty good information from that tracker not perfectly accurate but still useful information the idea is that that information should make you behave in a way that will make you more healthy so the next question is do these trackers actually improve your health well the first problem is that many people don't stick with their trackers about a third of people who buy a Tracker will stop using it by the six month Mark and about a half will eventually abandon it all together it's kind of like a gym membership people are really motivated to go to the gym at first but eventually especially if they don't know what they're doing that novelty wears off and if they don't see quick results the motivation Fades and if you look at the early studies of the impact of activity tracking on behaviors the results were not encouraging in one of the first major studies people with an activity tracker were slightly more active than people without but there were no improvements in their overall Fitness level and no changes in their weight or blood pressure in another major study they gave people an exercise routine along with a low calorie diet and weight counseling and when they added a fitness tracker into that mix it made no difference to physical activity what's worse is that people with trackers actually lost less weight than people without them and the theory there is that people might see their activity levels on the tracker and then kind of reward themselves for that exercise by indulging in eating that being said these technologies have come a long way since those early studies today's devices are waterproof they're easier to use they have a longer battery life and they use social media to connect people to support networks and all of that makes them more sticky and it helps to keep people engaged the largest review of the health impacts of wearables actually came out in August and they combined 39 other systematic reviews including almost 164 000 people and they concluded that activity trackers do have modest health effects they improve physical activity by an average of 1800 steps per day or 40 more minutes of walking per day and they lead to weight loss though the average is only about two pounds and these benefits are seen across studies in younger and older people and in healthy people as well as people with chronic diseases in fact patients with chronic diseases can also see improvements in blood pressure and cholesterol levels and that brings us to the Future already device makers are pushing the envelope and going from just monitoring Health to actually diagnosing and tracking illnesses for example in a recent study a smart watch was shown to accurately detect a heart rhythm abnormality called atrial fibrillation devices have also become pretty good at measuring sleep time and the newer ring device actually uses machine learning algorithms to try to identify the different stages of sleep so the bottom line is that activity trackers have come a long way they're not perfect sometimes that information is inaccurate and can lead to undue anxiety but they do represent a starting point ultimately though it's still up to you to find the motivation and the means to act on that information as technology evolves sensors will become better and tools like artificial intelligence will help us to tease out the most useful conclusions from increasingly large amounts of data from our trackers to some extent that's already happening and fitness trackers truly are evolving into Health trackers in the next few years I think they'll become part of my toolkit as a doctor to diagnose and manage certain conditions but also a tool that all of us can use to help achieve our health and fitness goals for more health and science info subscribe to the feed [Music] um foreign [Music]