With many different biometrics available through Biostrap and other wearables, it’s no surprise that it can be hard to make sense of a lot of the variables. Many of the measures change with lifestyle, age, and health conditions, so it is important to know what changes are meaningful. First and foremost, biometrics can be highly individual, so it is important to look at biometrics within each person over time, to see the trend. The biometric trend is important to follow because it will demonstrate directionality of change and significant deviations from an individual’s typical values. This is why Biostrap calculates an individual’s baseline and trends their biometrics over time.
So what is a ‘good’ biometric profile?
- Heart rate should be low. ‘Normal’ is between 60 and 100 beats per minute. However, bradycardia (< 60 bpm) is common for athletic individuals, since the heart is able to pump blood more efficiently. Over time, a reduction in heart rate due to training or lifestyle likely represents positive changes, although some medications and endocrine disorders may be responsible for a drop in heart rate. A rise in RHR over time is typically associated with decreased cardiac efficiency; left unchecked, a rising heart rate near or over 100 bpm can reflect increased risk of cardiovascular disease.
- Heart rate variability is highly dependent on the person, but most scientists and researchers note that higher HRV tends to be associated with increased health, wellness, fitness, and risk of certain diseases. HRV tends to change day-to-day more than RHR, and as such, reflects many lifestyle behaviors, such as training, psychological stress, environmental variables, alcohol, tobacco, marijuana, nutrition, etc. Because of its fluctuations, monitoring the trends in baseline provides more value than any specific day. Trends in HRV should generally be relatively stable or upwards, depending on training status, climate, season, etc.
- SpO2 should remain near 100%, with anything over 95% considered to be normal. As long as it is in this range over time, there appears to be little to worry about. However, a slow decline in SpO2 could indicate respiratory issues, such as COPD, pulmonary fibrosis, or severe asthma. Acute drops compared to baseline may represent respiratory illness, apnea events, altitude adaptation, or other oxygen uptake issues.
- Respiratory rate is another metric that cannot be compared between individuals as easily. Like SpO2, it responds to adverse situations regarding oxygen uptake or hypercapnia (buildup of CO2, which triggers increased breathing rate). Drastic increases in RR could indicate an acute infection, illness, fatigue, or other issues, while drifts upwards, especially paired with SpO2 decreases, could indicate chronic pulmonary issues.
- Arterial properties: Biostrap offers a number of PPG-based second-derivative metrics. Due to the novel nature of these algorithms, specific ranges cannot be recommended. However, general trends can be noted. First, baseline arterial and peripheral elasticity appear to be indicators of good vascular health, particularly in reference to aging of arteries. Over time, these values may trend downwards as arteries lose compliance; however, when tracked according to baseline, some of the metrics may show unique changes that have yet to be understood. For example, both extreme exercise and infection appear to increase arterial and peripheral elasticity in the short term. Extreme exercise may be a result of lingering signaling molecules, such as epinephrine/norepinephrine or nitric oxide and other vasoactive compounds (i.e. arachidonic acid metabolites). However, acute infection demonstrates increases in elasticity measures that appear counterintuitive and require more research.
