Denver’s Dark Skin: Is Altitude Hiding Tracker Lies?

By Franklin Everett Shaw

May 28, 2026

Are you a Denver resident with darker skin, hitting the trails and wondering if your fitness tracker is actually tracking your vitals accurately? You’re not alone. The thin air of the Mile High City presents unique challenges, and the technology we rely on might not be as colorblind as we think. Let’s dive into the science, the biases, and what you can do about it.

Wearable fitness trackers, while convenient, aren’t perfect. Their accuracy can be affected by various factors, including skin pigmentation and altitude. This is especially relevant for Denver residents with darker skin tones, where the combination of these factors can lead to unreliable readings.

Pulse oximetry, a key feature in many fitness trackers, measures blood oxygen saturation (SpO2) by shining light through the skin. Melanin, the pigment responsible for skin color, absorbs light. Higher melanin levels can interfere with the light signal, potentially leading to inaccurate SpO2 readings, particularly at higher altitudes where oxygen levels are already lower.

Heart rate monitoring, often done using photoplethysmography (PPG), also relies on light. Similar to pulse oximetry, melanin can affect the accuracy of PPG-based heart rate measurements. This can be problematic during exercise in Denver, where the body’s physiological response to altitude (increased heart rate) needs to be accurately tracked.

So, what’s a Denverite to do? First, understand the limitations. Don’t blindly trust the numbers your tracker spits out. Consider these factors:

• Altitude Acclimatization: Your body adapts to the lower oxygen levels over time. Track your SpO2 over several weeks to establish a baseline.
• Hydration: Dehydration thickens the blood, potentially affecting readings. Stay well-hydrated, especially at altitude.
• Skin Temperature: Cold extremities can constrict blood vessels, impacting blood flow and affecting readings. Ensure your hands are warm during measurements.

Here’s a DIY calibration guide, acknowledging its limitations but offering a starting point:

1. Find a Baseline: At rest, compare your tracker’s SpO2 reading with a fingertip pulse oximeter (available at most pharmacies). Do this multiple times over several days.
2. Note the Discrepancy: Calculate the average difference between the two readings. This is your personal “altitude/skin tone correction factor.”
3. Apply the Correction: Mentally adjust your tracker’s readings by adding or subtracting your correction factor. This is not a perfect solution, but it’s better than nothing.
4. Exercise Test: During exercise, compare your tracker’s heart rate with your perceived exertion level (how hard you feel you’re working). If the tracker consistently underestimates your heart rate, it’s likely inaccurate.
5. Consult a Professional: This DIY method is a temporary fix. A proper assessment requires professional medical equipment and expertise.

Let’s be clear: this DIY calibration is a workaround, not a solution. The best approach is to seek out alternatives and professional guidance.

Consider these alternatives for more reliable data:

• Chest Strap Heart Rate Monitors: These are generally more accurate than wrist-based monitors, as they directly measure electrical activity in the heart.
• Fingertip Pulse Oximeters: While still susceptible to some skin tone bias, they are often more accurate than wrist-worn devices.
• Medical-Grade Devices: If accurate SpO2 readings are critical (e.g., for managing a respiratory condition), consult your doctor about using a medical-grade pulse oximeter.

The challenge lies in the inherent biases in the technology. Manufacturers often test their devices primarily on individuals with lighter skin tones, leading to algorithms that are less accurate for people with darker skin. This isn’t necessarily intentional, but it highlights a critical need for more diverse testing and algorithm development.

Common pitfalls developers face include:

• Lack of Diverse Datasets: Training algorithms on predominantly light-skinned individuals.
• Ignoring Environmental Factors: Failing to account for altitude, temperature, and other variables.
• Over-Reliance on PPG: Not incorporating other sensors or data sources to improve accuracy.

To overcome these challenges, developers need to:

• Prioritize Inclusive Testing: Include individuals with diverse skin tones in all stages of testing.
• Develop Skin Tone-Agnostic Algorithms: Explore alternative measurement techniques or algorithms that are less susceptible to melanin interference.
• Incorporate Environmental Data: Use sensors to measure altitude, temperature, and humidity, and adjust readings accordingly.

For personalized skin health and fitness assessments in the Denver area, consider these resources:

• Dermatologists:
  • Colorado Dermatology Institute (Denver): Specializes in skin of color.
  • Advanced Dermatology & Cosmetic Surgery (Multiple Locations): Offers comprehensive skin care services.
• Exercise Physiologists:
  • National Jewish Health (Denver): Renowned for respiratory and altitude-related research.
  • Peak Performance Solutions (Boulder): Focuses on optimizing athletic performance at altitude.

Remember, your health is paramount. Don’t let inaccurate data from a fitness tracker mislead you. Use these tools as a guide, but always listen to your body and consult with healthcare professionals for personalized advice. The goal is to thrive in Denver, not just survive, and that starts with accurate information.