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How To Decode Your Wearable Data, According To A Performance Medicine Doctor

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May 16, 2022
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It seems that everyone has at least one device they wear regularly that tracks some aspect of health-related behavior. It could be an Apple Watch tracking how often they take deep breaths and move, an Oura ring tracking sleep, a Whoop band assessing exercise intensity and "strain," or a Fitbit tracking steps. We have become quite the human data repositories. But other than providing the companies collecting this data with valuable insights into our habits, what else can be gained from all of this? 

Some don't glean much from their wearables other than the occasional glance to check step count. Others try to understand what it says about their sleep routine, dietary habits, or fitness regimen—then, after a couple of weeks, they stop checking, unsure what to do with that information.

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Yet, many people keep wearing the device or just leave it on the charger indefinitely. If any of that hits close to home, then let me help you out.

The health benefits of data.

As a physician specializing in personalized performance medicine, I love data. Peter Drucker, an expert in business process optimization, supposedly said something akin to "you manage what you measure," and while this may not be true in all cases, it does apply to your health when you are trying to improve it.

For example, we know that maintaining healthy blood pressure levels can affect cardiovascular health outcomes1. That is why we have blood pressure checks as a routine part of a physical exam. Similarly, waist circumferences, blood sugar levels, and more can be markers of metabolic health.

As it turns out, many of the biomarkers tracked by this new generation of wearables actually do correlate with significant health repercussions, just like these traditional quantifiable measures.

How can wearables improve performance?

Even beyond improving health, measuring particular metrics and managing your lifestyle habits based, in part, on them can help you achieve your broader performance goals (such as wanting to be more focused or energetic, win a race, or perhaps perform better at work). Some of these wearables can give you insights into how your behaviors—around sleep, stress management, or physical activity, for example—may affect how successful you are at achieving those goals.

So in terms of health and overall performance, let's look at some examples of how these metrics can be useful to track:

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It has been shown that the quality and quantity of your sleep affect your physical and mental health, creativity, and mood. What's more, multiple studies attest to quantity and quality of sleep correlating with academic,2 work3, and athletic performance.

While we can manually keep track of what time we go to bed and when we wake up, what matters is the amount of time we are actually sleeping between those two events. It is also important to have sufficient time in the most restful states of sleep: deep sleep and REM sleep. That is what determines sleep quality. Deep sleep is important for physical rest, and REM sleep is especially important for creativity and mental rest (such as cementing memories).

The insight into your sleep quality obtained from some wearable devices can be very helpful if you use them to assess what behaviors affect your ability to get the quality and quantity of sleep you need to perform at your best.

How to best use a tracker for sleep? Don't just measure your slumber time—also keep track of behaviors that may be affecting your sleep quality or quantity. For example, we know that the timing of meals, pre-bed screen time, drinking alcohol or caffeine, and working from bed can all affect sleep.

In order to get the most from your sleep data, compare it to these other behaviors, which you may have to track manually. Looking at this data side by side may enable you to see what has the most impact on your sleep, which will be different from someone else. 

For example, your buddy may be able to have one to two beers and have no problem sleeping through the night, but that may make you crash only to become wide-awake at 2 a.m. On the other hand, you may be able to work in bed all day, but he may not be able to fall asleep easily if he does the same.

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Does the number of steps you take really affect your health or your performance goals? In a word: yes.

We know that physical activity is extremely important in staying healthy, yet only 20% of Americans get the recommended 150 minutes a week. Many of us overestimate the amount we actually do get, so the tracker can keep you honest with yourself.

As with sleep, use the data to see how the amount of activity you have correlates with your goals, whether it's better sleep or feeling less stressed. You'll likely find a correlation.


Heart rate variability (HRV)

Heart rate variability (HRV) is a metric proven to reflect your stress level4. This is because when you are stressed, your sympathetic nervous system is in high gear. Normally we have a nice high level of variability in our heart rate, but when our nervous system is in stress mode, that variability goes down as our heart rate stays higher, anticipating that need to fight or flee. Being in this state for long periods of time means the body is focused on survival rather than taking care of maintenance functions, including immunity and digestion. Thus, low HRV means those systems aren't working optimally. Not to mention, stress affects aging for the body and brain.

The way to best use this metric is not to compare yourself to others but rather to compare yourself to, well, yourself. Try different strategies to get that HRV higher–meditation, breathwork, exercise, or journaling, for example.

You can also use it to help tune into what a lot of emotional stress feels like in your body. So when you see a low HRV, try to do a body scan to see how that feels, and where you experience stress in the body. You may notice tightness in areas you hadn't paid attention to. Then, with time, you won't even need to see the HRV to sense you are stressed. From there, you can employ whichever relaxation technique you discovered works well for you.

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The takeaway.

We live in an unprecedented age of data and the quantified self. If you are able, I encourage using the available resources to gain true insights into your own health and what works best for you, in order to become even healthier and to get closer to achieving your goals.

Myles Spar, M.D., MPH
Myles Spar, M.D., MPH
Internal & Integrative Medicine Doctor

Myles Spar, M.D., MPH, is a highly sought-after medical expert in personalized and performance medicine, men’s health, advanced testing and integrative medicine.

Spar is an author, teacher, clinician and researcher, having published the book Optimal Men’s Health in 2020 with Oxford University Press. As a specialist in Integrative Men’s Health, he has advised NBA players, celebrities and executives on maximizing performance through optimizing health. He has contributed articles to the L.A. Times and Men’s Journal and has appeared on multiple national media outlets and is a clinical faculty member of the University of Arizona School of Medicine.

Spar is the Chair of the American Board of Integrative Medicine and a veteran of Doctors Without Borders as field worker and board member. He is the recipient of the prestigious Bravewell Leadership Award, the highest honor in his field. Spar is board-certified in Internal and Integrative Medicine and practices in-person in New York City and virtually across the United States.