Whether a smartwatch or a ring, many of us now wear fitness trackers, which means we have collected a lot of data on how much we are moving and sleeping, as well as how our heart rates change with our activity levels. All of this information can be a good motivator for getting you moving more regularly and monitoring your overall health — but it might also be useful to your doctor.
It’s not always clear to the users what all that health data means, which means you might not know what and how to address it with your doctor. In order to gain a better understanding of what fitness tracking data will actually be useful for your doctor to know, we asked a cardiologist and sleep specialist for their thoughts.
“The algorithms that are used are all different across the different companies and different devices, so we have to take these details with a grain of salt, but there is still a lot of information we can get from it,” said Tomiteyo Oyegbile-Chidi, MD Ph.D., a neurologist and sleep specialist and a faculty member at UC Davis. “I wouldn’t make any diagnoses based on [tracker data], but it helps to make inferences on what tests to do.”
Activity trackers can function as a sleep diary
Oyegbile-Chidi often asks her patients to write a sleep diary, including when they go to bed and when they wake up. This is where an activity tracker can be handy, as they often automatically record this information, and their data is likely more reliable than what we might write down ourselves.
“The most important thing is seeing the bed-time and rise time,” Oyegbile-Chidi said. “That tends to be pretty accurate and can be helpful.” Sleep data from an activity tracker can also help her get a sense of how restless a person is during sleep. “This gives a general sense of whether you tend to wake up a lot and walk around or if you are someone who stays in bed most of the time,” Oyegbile-Chidi said. “That can be helpful, too.”
Fitness tracker data is most useful when looking for behaviour patterns that might affect your overall health, such as the average time you go to sleep, average time you wake up, as well as any periods of reduced sleep. “Trends are very, very helpful,” Oyegbile-Chidi said.
Sleep information can also be helpful for a cardiologist. “Poor sleep can affect blood pressure and arrhythmias,” said John Higgins, MD, a cardiologist with the McGovern Medical School at UTHealth Houston, so an established record of disrupted sleep can indicate a problem that warrants deeper consideration.
What isn’t all that helpful are your tracker’s estimates of when you enter various sleep stages, as well as its gauge of your overall sleep quality, as those tend not to be all that accurate.
Resting heart rate information can act as a barometer for your health
Your tracker’s heart rate data, which can include resting heart rate, heart rate variability, and heart rate during exercise, covers a lot of ground. As with sleep data, you need to take this information with a grain of salt, as it’s not always 100% accurate, but looking at long-term trends can be useful for your doctor.
“Average resting heart rate is a barometer of health for healthy patients,” Higgins said. If you notice your average resting heart rate is trending up or down over a period of time, that’s something that you might want to talk to your doctor about.
Resting heart rate data can also be useful for patients with heart conditions, as it can help indicate whether their medications are working or if they need to have their dosage adjusted.
Heart rate variability can indicate overtraining or stress
When we talk about rest and recovery, heart rate variability is a useful metric for detecting the effects of stress, poor sleep, or overtraining. Unlike your resting heart rate, which tends to be fairly stable over a long period, heart-rate variability is responsive to short-term conditions.
For a cardiologist, this data can also be helpful when monitoring their patients. “Trackers that monitor heart rate variability may give an early warning of worsening in heart condition,” Higgins said. Some trackers are now able to detect abnormal heart rhythms, such as atrial fibrillation. If your tracker detects this type of activity, you’ll want to talk to your doctor right away so they can follow this up with further tests.
Bring up any concerns with your doctor
The data a fitness tracker collects can be hard to parse, and though it can be useful for helping you doctor detect certain long-term trends or provide them evidence of what they might need to test for, the information isn’t definitive. Before you start worrying too much about what you think your smartwatch is telling you about your health, talk over your concerns with your doctor. “It’s not necessarily the gospel truth,” Oyegbile-Chidi said.