How to Get the Most Out of Your Health Trackers
In this technological era we have the ability to track many health metrics via devices like the Oura ring, Apple watch, and Polar Ignite watch among many others. Most of these devices use an algorithm to give you a “readiness” score for the day by taking into account all of the different metrics that the device is tracking. We can follow so many different markers these days that we should never have any doubt of when to go hard and when to rest, right? The answer should be a resounding yes, but I think it’s easier to interpret our “readiness” scores when we understand the metrics behind these calculations. Most of us are familiar with tracking our resting heart rate, but now it’s common to track heart rate variability (HRV), body temperature, breathing rate, and detailed sleep data. Below I give a description of the most common metrics and what they can tell us.
RHR (Resting Heart Rate):
Resting heart rate (RHR) is one of the most common metrics used to track recovery, and we measure it as the number of times our heart beats in a one minute interval. It gives us an indication of how we’re recovering from our training, and acts as a warning signal when we may be fighting an infection. In the past it was common for us to check our RHR when we woke up in the morning, but now we have devices that can track our heart rate 24 hours a day, and give us detailed information on what our heart rate is doing while we sleep. We can gather much more information from looking at a graph of our overnight heart rate rather than simply checking what it is when we wake up in the morning. Our previous day’s activity level, diet, and alcohol consumption will all have an effect on our heart rate during the night. Tracking and comparing these trends over time can help us make changes to maximize our recovery.
HRV (Heart Rate Variability):
Heart rate variability (HRV) is the variation of heart beat to beat intervals. Logically we might think that our hearts should beat like metronomes, but in reality a greater variance between beats indicates better overall health. Our HRV scores can help us decide if we’re ready to train hard or if we need a little more recovery. In general, a lower HRV (more constant beat intervals) indicates a need for more recovery, and a higher HRV (more variance between beats) indicates that you’re recovered and ready to go. There are many factors that influence HRV, including genetics, activity level, stress levels, sleep quality, diet, and hormone cycles. It’s important for us to compare our scores to our own baselines, and not to compare with others.
HRV is regulated by the autonomic nervous system, which controls many aspects of our health including respiration, digestion and cardiovascular function. The autonomic nervous system has a parasympathetic branch and a sympathetic branch. The parasympathetic branch is known as the rest and digest system that helps us recover after working the sympathetic, or “fight or flight “ branch of the system. In general when we engage our sympathetic systems our HRV lowers, and when we are in rest and digest mode our HRV goes back up. So, it’s normal for our HRV to drop after a hard workout (engaging the sympathetic system), but we expect it to rebound after a few recovery days. When we see a trend of HRV staying below our normal levels, we may need more recovery time between workouts. If a low HRV trend becomes more long term, we may want to consult a health professional.
Body Temperature:
Tracking body temperature is an easy and sometimes overlooked way to monitor our health. An elevated body temperature can indicate that we’re fighting off an infection and need some extra easy or rest days. We can also track long term trends in body temperature to be aware of possible changes to our overall health. Women can use body temperature to track their menstrual cycles, and it’s important to keep this in mind when body temperature is elevated, so we can assess whether it’s due to the hormone cycle or a potential infection.
Breathing Rate:
Many devices can now track our overnight breathing rate, or the number of breaths that we take in one minute. For most people this is somewhere between 12 and 20, but like most health metrics it’s highly individual, and important that we compare our scores to our own baseline. Our breathing rate will typically go up when we have a respiratory infection, and may stay elevated even after our symptoms are gone, indicating that we aren’t fully recovered and may need additional rest. Similar to body temperature, women tend to have more variability with their breathing rates that is tied to the hormone fluctuations of the menstrual cycle.
Sleep Data:
Most health trackers that we wear overnight provide us with a detailed report on our sleep stages. Typically this is categorized by the time we spend in light, deep and Rapid Eye Movement (REM) sleep. We go through 3-5 sleep cycles each night, averaging around 90 minutes each. Normally we get more deep sleep and shorter periods of REM sleep earlier in the night, while towards morning our REM periods tend to lengthen after we’ve met our need for deep sleep. We can track our trends and see how training load, diet and stress levels effect the time we spend in each stage of sleep.
Here’s a brief description of deep, REM, and light sleep:
Deep: Deep sleep is the most restorative of the sleep stages. This is when our bodies release human growth hormone (HGH) and restore our muscles. We also balance out blood sugar and metabolism during deep sleep. Our brain waves are slow during this phase (called delta waves) and it is usually difficult to wake someone during this stage of sleep. We also don’t dream during deep sleep. Deep sleep typically accounts for 10-25% of a person’s sleep for the night.
Rapid Eye Movement (REM): REM sleep is the stage when our brain waves are most similar to when we’re awake. Our brain is active and we dream during this phase of sleep, although our bodies are inactive. REM sleep is when we clear the brain of things that aren’t needed, and it’s important for memory consolidation. It typically accounts for 20-25% of a person’s sleep for the night.
Light: Light sleep makes up the majority of our night. Body maintenance and cell repair takes place during this phase, just not to the same extent as during deep sleep. We also processes memories and emotions during light sleep.
In Summary:
Whether we like to keep it simple and just look at one score for the day or if we enjoy analyzing all of the details, health metrics can help us decide when to push and when to hold back. It’s interesting to see how we respond to different types of training, changes in our diet, life stress, and even the effects of travel. This health data is a great window into what’s going on in our bodies, and the more we learn the more we can refine our training to get the maximum benefit, since staying healthy is key to achieving our goals!