A Comprehensive Guide to Biometrics

Biostrap is committed to delivering clinical-grade biometrics which help you optimize your fitness and wellness goals and routine, but how do we measure these vitals and what do they really mean?

How Biostrap Measures Your Biometrics

Biostrap uses red lights to measure heart rate through a 150-year old process called photoplethysmography (PPG). PPG works in the following way: a LED light source shines onto the skin and light bounces back into the photodetector, recording how the light’s intensity changes as blood perfuses through the tissue. Data picked up by the photodetector use signal processing algorithms to convert the variations into a heart rate.

Red light PPG sensors (also called pulse oximeters) utilize light in near-infrared spectroscopy (NIRS) and are widely used by doctors’ offices and hospitals, where accuracy is closely monitored and absolutely essential for medical use.

Our bodies do not absorb red light well which is actually a good thing; it allows the transmission to penetrate 10x deeper into multiple tissue layers in order to obtain a number of biometric signals (such as hydration, muscle saturation, total hemoglobin, and more). Additionally, tattoos, freckles, and melanin in the skin do not affect readings by red light sensors.

Understanding Your Biometrics

Biostrap delivers accurate reads on Heart Rate Variability, Resting Heart Rate, Blood Oxygen Saturation Levels, and Sleep Tracking. When it comes to understanding the nuances of these vitals, learning about their roles in our bodies is essential. Here’s an overview of a few of our cornerstone metrics for delivering actionable health insights:

Heart Rate Variability

Understanding the role of heart rate variability in a healthier lifestyle requires a general knowledge of what the biometric is and how it affects our bodies.

High Versus Low
Although it may sound counterintuitive, a low variance—a steady, consistent pattern of heart beats—is not the healthiest state for your body to be operating in. Higher interval variance, or significant changes in time between beats, means your heart is working in a healthy, sporadic way. Your body constantly needs blood and nutrients, but a healthy heart pumps only when necessary, fluctuating in activity as the body calls for it.

High HRV
Generally speaking, higher heart rate variability is indicative of the control of the parasympathetic system, one of the two sides of the autonomic nervous system. This system is responsible for regulating the body’s unconscious actions including sexual arousal, salivation, and digestion––often called the “rest and digest” system.

Low variance in between heart beats, or a consistent heartbeat, indicates a dominance of the sympathetic system. This system’s primary process is to stimulate the body’s fight-or-flight response but, when experienced without a threat, is signaling stress, overtraining, and inflammation.

A Comprehensive Guide to Biometrics 1

Healthier Lifestyle
Having access to all this insightful data packaged neatly for you inside a mobile app is great, but how can it lead to a healthier lifestyle?

For one, your fitness routine can benefit immensely from simply exercising when your body is rested. An intense workout can keep your heart rate variability low for days as your body recovers. Rather than putting yourself at risk of overtraining, which can lead to muscle damage or mood imbalances, heart rate variance data can keep you active at the most opportune of times.

Resting Heart Rate

Resting Heart Rate is a measure of how fast the heart beats per minute (bpm) while standing, sitting, or lying down — but not sleeping — and best measured first thing in the morning. The average adult will have an RHR between 60-100 beats per minute, while athletes are likely to rest somewhere between 40-60 bpm. And the lower, the better, as RHR indicates the health of the heart leading to overall longevity, lower risk of heart attack, higher energy levels, metabolic efficiency, and athletic endurance.

What Affects Resting Heart Rate?

1. Regular Exercise. At least 1 hour of sustained aerobic exercise (such as brisk walking, cycling, or jogging) three times per week will help maintain a lower RHR. It’s important that whatever the exercise, it increases heart rate for an extended period of time.

2. Hydration. Staying hydrated helps with blood viscosity and allows the blood to flow through the body more easily, exerting less stress on the heart.

3. Sleep. During consistent, uninterrupted sleep, the body rests, repairs, and recovers. Poor or inconsistent sleep can be a large contributor to elevated RHR, putting stress on the heart.

4. Diet. A balanced diet full of healthy fats and low sodium keeps arteries clear, leading to lower RHR and less work for the heart.

5. Stress. Over the short and long-term, stress can create extra work for the heart, increasing RHR. It’s important to keep stress and anxiety low to maintain a strong RHR.

Why Measure RHR?
As with most body metrics, Resting Heart Rate offers insights into your overall health, indicating general wellbeing as well as potential health risks which can inform your daily lifestyle choices.

For athletes, knowing your RHR as well as your Maximum Heart Rate (MHR) can help dictate heart rate based training zones. Spikes in RHR can indicate when overtraining has occurred and an athlete should take a rest day, something else in a training regiment is amiss, or can even indicate an oncoming cold or illness.

Blood Oxygen Saturation

Blood oxygen saturation (abbreviated SpO2) is a measure of how much oxygen the blood is carrying and can be measured using a pulse oximeter without using a needle. This is a percentage of how much oxygen is in your blood compared to the maximum it is capable of carrying. Typically, when red blood cells pass through the lungs, 95%-100% of them are loaded, or “saturated,” with oxygen. Generally, more than 89% of your red blood should be carrying oxygen at any given time.

How Pulse Oximeters Work
Beams of red and infrared light from the pulse oximeter device pass through the bloodstream to measure the percentage of hemoglobin. You will not feel this happen. Measuring this way is possible because hemoglobin is a different color with and without oxygen, and absorbs different amounts of light depending on the oxygen level. The difference between the amount of absorption provides an accurate level of your oxygen saturation.

Know Your Blood Oxygen Saturation Level
The body lives off of oxygen as an energy source, and it keeps the body functioning normally. Most people need a minimum SpO2 level of 89% to maintain healthy cells; anything lower can cause strain on the heart, lungs, and liver and keep the body from functioning properly.

Low SpO2 levels are known as hypoxia and can be a sign of lung disease or sleep apnea, which may necessitate supplemental oxygen to maintain healthy functioning and prevent long-term damage to the cells. Other potential causes of hypoxia include asthma, emphysema, pneumonia, heart problems, and anemia.

When exercising, SpO2 levels indicate how much oxygen is reaching the muscles during a regular workout, so it is important to know SpO2 levels just after activity. High blood oxygen levels mean the body will transport oxygen throughout the body quicker, indicating efficient and intense workouts; low blood oxygen levels mean the body will send oxygen to the muscles at a much slower rate, causing fatigue and a less effective workout.


When you don’t get enough sleep, or poor quality sleep, it has an immediate impact on your mood and alertness, but did you know sleep is also a vital component of overall health?

Sleep and Overall Health
Sleep influences all of the body’s major physiological systems, including thermoregulatory, musculoskeletal, endocrine, respiratory, cardiovascular, gastrointestinal, and immune systems, as well as weight. Therefore, sleep and health are closely related— when you’re not at your healthiest your sleep quality suffers, and when your sleep quality suffers it can have negative health consequences. 67% of people with less than good sleep quality also report “poor” or “only fair” health.

Extended periods of too little sleep can impact professional and social performance as well as increase the risk of obesity, diabetes, high blood pressure, heart disease, stroke, and frequent mental distress. Mood problems, anxiety and depression, and increased risk of accidents can also be exacerbated by lack of sleep. However, these are all effects of short and long-term sleep debt, which can be made up over time by altering sleep patterns and habits— consistently getting more sleep and higher quality sleep each night.

Why don’t we get enough sleep?
In recent years, research has shown that the blue light from electronic devices such as phones, tablets, and televisions can have a negative impact on our sleep. Like sunlight, blue light affects circadian rhythm by halting melatonin production; this disruption leads to less sleep and poorer quality sleep. Easy access to technology also leads to longer workdays and increased alertness while playing games or reading the news at night.

Stress and sleeping disorders are also common sleep detriments. Rather than relaxing or unwinding before bed, many Americans focus on activities which heighten their stress levels, such as responding to emails. High stress levels can lead to insomnia and other undiagnosed sleep disorders such as sleep apnea, which not only impact duration and quality of sleep, but can generate serious health risks.

Make the most of your biometric data with Biostrap and to unlock your optimal health and fitness goals.

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