Abstract

The Tymewear VitalPro is a wearable chest strap that measures ventilation and heart rate designed to capture breath-by-breath ventilation signals during exercise. This study validates the VitalPro against the Cosmed K5 metabolic cart—a gold-standard tool for metabolic and ventilatory assessment—for continuous respiratory metrics including breathing rate (BR) and minute ventilation (VE). BR measurements from the VitalPro demonstrated high agreement with Cosmed data with a mean absolute error (MAE) of 1.2 breaths per minute. Minute ventilation also showed a strong pooled correlation (r = 0.973, r² = 0.947). These results support the use of the Tymewear VitalPro as a reliable tool for field-based respiratory performance monitoring.

Introduction

Reliable and accessible measurement of respiratory metrics during exercise is vital for both performance diagnostics and clinical assessments. Traditional metabolic carts, such as the Cosmed K5, provide accurate measurements but are limited by cost, portability, and user accessibility.

Ventilation alone has been shown to be sufficient for detecting ventilatory thresholds during ramp protocols, opening the door for user-friendly devices to deliver insights that previously required lab visits.

Tymewear’s VitalPro offers a wearable, chest-worn solution that enables breath-by-breath respiratory monitoring during real-world exercise. This study aims to validate the VitalPro against the Cosmed K5 during incremental cycling tests. We evaluate both continuous respiratory metrics breathing rate and minute ventilation.

Methods

2.1 Participants
26 male and female athletes (age 27 ± 21 years) participated in the study. All subjects were healthy and free of cardiovascular or pulmonary disease.

2.2 Protocol
Each subject completed a ramped VO₂max cycling test indoors on a stationary bike, wahoo kickr. Each stage of the ramp test was 3 minutes long and power was increased by 20 W after each stage. The Tymewear VitalPro and Cosmed K5 were worn simultaneously. Data were collected from both devices for the entire test duration.

2.3 Devices
VitalPro: A wearable, chest-worn sensor capturing ventilatory movement with high-resolution sampling at 25 Hz.Cosmed K5: A portable metabolic cart recording breath-by-breath VO₂, VCO₂, ventilation, and derived metrics.

2.4 Data Processing
Signals from the two systems were aligned based on maximum minute ventilation. Tymewear breathing rate was processed in the same way it’s shown live during workouts, with an outlier rejection algorithm that discards 2 out of every 5 breaths. Minute ventilation was also processed in the same way as is done live on the device, with a simple moving average of 3 breaths. Cosmed data was processed in the same way as Tymewear data for consistency. Metrics were compared using Pearson correlation and mean absolute error (MAE). A Fisher's z transformation was used to pool correlation coefficients across datasets, weighted by the number of data points in each trial.

Results

3.1 Breathing Rate (BR)
Mean Absolute Error: 1.2 breaths/min

3.2 Minute Ventilation (VE)
Pooled Pearson Correlation (r): 0.973 (r² = 0.947)

Correlation coefficients were calculated for each session, transformed using Fisher’s z, weighted by the number of data points, and then back-transformed to obtain a pooled estimate. This yielded a pooled Pearson correlation of r = 0.973 (r² = 0.947), indicating strong linear association between the VitalPro and Cosmed K5 VE measurements across all trials.

Discussion

This study validates the Tymewear VitalPro as a reliable and accurate wearable for measuring respiratory metrics during exercise and for detecting key ventilatory thresholds. Results demonstrated that breathing rate (BR) from the VitalPro showed high agreement with Cosmed K5 data, while minute ventilation (VE) demonstrated strong linear association. The mean absolute error (MAE) of only 1.2 breaths per minute. VE comparisons also yielded a strong correlation (r = 0.973), supporting the accuracy of the VitalPro’s breath-by-breath ventilatory signal.

These findings suggest that Tymewear offers more than passive ventilation tracking—it provides actionable, lab-quality insights in a portable and accessible format. This opens the door to democratized performance testing, enabling athletes of all levels to benefit from physiological threshold training without the barriers of lab testing.

It’s noteworthy to point out that the Cosmed dataset was not the same length as the Tymewear dataset. This is due to differing processing algorithms where some breaths may not be detected on one system or breaths are detected where there are none. When digging into the raw data of each device it was clear that the processing algorithms used by Cosmed are quite conservative and tend to drop breaths when there is a noise profile associated with it. The resulting dataset was therefore a few breaths shorter on the Cosmed side.

This complicates breath detection accuracy because the Cosmed system timestamps data only at whole-second intervals, without sub-second resolution. Therefore the method used to compare the two signals in this study was to create a common time axis and interpolate between the datapoints so that the signals could be compared in the most consistent way. This inescapably results in a slightly lower correlation and accuracy since each datapoint can be shifted by a few milliseconds with respect to the other signal instead of a direct breath by breath signal comparison.

We’ve now gained access to the raw flowmeter data from Cosmed and intend to parse it with our own breath detection algorithm to perfectly line up the Cosmed and Tymewear detections so that accuracy can be assessed in an even more consistent manner.

In summary, the Tymewear VitalPro performs with high validity in both continuous respiratory monitoring and threshold detection. It provides a practical, accurate, and scalable alternative to metabolic carts, and has the potential to transform how athletes and coaches approach training personalization.

Conclusion

The Tymewear VitalPro provides accurate, reliable respiratory monitoring compared to the Cosmed K5. It’s breath-by-breath ventilation tracking shows promising agreement with laboratory measurements, enabling meaningful training and performance insights in real-world settings.

Plots