5 Takeaways: Duke University’s Wireless Sensor Technology Webinar

Cardiorespiratory fitness (CRF) is emerging as one of the most powerful biomarkers for health, longevity, and overall risk assessment. 

In a recent Duke University webinar, Dr. Jeroen Molinger, Research Program Director and Lead Clinical Medical Exercise Physiologist, explored the latest advancements in wireless sensor technology and its impact on conducting cardiopulmonary exercise tests (CPET). 

Here are the five key takeaways from the session.

1. Cardiorespiratory Fitness is a Critical Health Biomarker

CRF is more than just a measure of endurance—it’s a comprehensive indicator of overall health. 

Unlike single-organ biomarkers, CRF integrates data from the heart, lungs, and muscles, offering a more holistic picture of an individual’s physiological status.

“I think it’s a powerful biomarker because it is such an integrative biomarker, not a single-organ biomarker,” says Dr. Molinger. “We have the ability to couple the lungs, the heart, and the muscle to specifically see which system is more or less limited, which defines a higher or lower CRF.”

• A 2009 study by Saturo Kodama published in JAMA found that CRF is a robust predictor of all-cause mortality and cardiovascular events.
• Another study by Mandsager analyzed data from 122,000 individuals, showing that even minor improvements in CRF (e.g., moving from a low to below-average category) can result in a 95% reduction in overall mortality risk.

2. The Evolving Methods of Measuring VO2 Max

Traditionally, assessing CRF and VO2 max required either questionnaires, smartwatches, or CPET with bulky metabolic carts. However, these methods present challenges:

• Questionnaires provide estimates but lack precision.
• Smartwatches (Garmin, Apple, Fitbit) use indirect algorithmic calculations.
• Traditional CPET is costly, requires specialized equipment, and isn’t scalable.

This led to a pressing question. 

“Can we create a point-of-care assessment?” asks Dr. Molinger. “Ideally, something that you do at the bedside in a time frame of 8-12 minutes and have the ability to do it for direct reporting anywhere—without the need for specific hardware like treadmills or bicycles.”

Duke University has introduced Splendo, a platform that integrates multiple wireless sensors, including the VO2 Master, to provide real-time, portable, and accurate CRF assessments—without the need for treadmills or bicycles.

3. The 6-Minute Incremental Step Test (6MIST): A Game-Changer in CRF Assessment

To make CRF assessment more accessible, Duke researchers developed the 6-Minute Incremental Step Test (6MIST)—a simple, space-efficient protocol that can be performed anywhere. Participants march in place at increasing speeds guided by a metronome, making it easy to assess different fitness levels.

“In our validation, our Hartford population, everyone started with 30 beats per minute,” explains Dr. Molinger. “We increased by ten every 30 seconds, with the 70 BPM level reserved for athletes with VO2 higher than 30-35.”

• In a validation study, even heart failure patients completed the test safely, reinforcing its broad applicability.
• A comparison of 6MIST and CPET on a bike showed a high correlation (R-squared of 0.75) in healthy volunteers, confirming the test’s reliability.

4. Validating VO2 Master Against Metabolic Simulators

Ensuring the accuracy of portable metabolic testing is critical. Duke’s research compared VO2 Master against a Vacumed metabolic simulator, which can generate specific VO2 levels.

“We saw a very well-defined high R-squared for VO2 and also for ventilation efficiency, same for the tidal volumes and frequency,” Dr Molinger explains. “What’s interesting is that the error margin overall was below 2%, and that’s very, very good for a metabolic simulator—even if it’s a full cart. I think that proves that the technology we use in this wireless metabolic framework works very well and gives you very valid numbers.”

This validation supports the use of wireless, portable CRF assessment tools in both clinical and athletic settings.

5. Cutting-Edge Performance Assessments in Elite Athletics

Duke’s Cardiovascular Performance and Innovation Lab has taken CRF testing beyond the clinic and into the world of elite sports. Working with D1 teams in soccer, basketball, and more, they’ve implemented a 1-minute all-out protocol that maximizes efficiency.

“This specific assessment is so short,” says Dr. Molinger. “With three systems, we tested about 30 athletes in 2.5 hours with full reporting.”

• The data provides critical insights into VO2 max, VO2 peak, and specific physiological limitations, from ventilation mismatches to mitochondrial respiration efficiency.

The Future of Wireless CRF Testing

As wireless sensor technology continues to evolve, its impact on longevity, healthcare, sports science, and clinical research will be profound. Duke University’s advancements in integrating VO2 Master and other wireless sensors pave the way for more accessible, scalable, and accurate cardiopulmonary assessments—without the barriers of traditional CPET systems.

Stay tuned for the upcoming Spring 2025 publications from Duke University detailing these findings, and expect to see wireless CRF testing continue its rapid growth in fitness, health and athletic performance assessments globally.