AirBands Validity and Reliability

Research SummaryAug 20, 2024Last Updated: Aug 21, 2024

Study Information

Zhang, W. Y., Zhuang, S. C., Chen, Y. M., & Wang, H. N. (2024). Validity and reliability of a wearable blood flow restriction training device for arterial occlusion pressure assessment. Frontiers in Physiology, 15, 1404247.

https://doi.org/10.3389/fphys.2024.1404247

Purpose of the Study

This study aimed to evaluate the validity, inter-rater reliability and test-retest reliability of VALD’s AirBands Wireless Blood Flow Restriction (BFR) Cuffs for measuring Arterial Occlusion Pressure (AOP) in the lower limbs. This was accomplished by comparing the AOP measured from AirBands to the AOP measured using a Doppler ultrasound, which is considered the gold standard method. Additionally, the study aimed to understand the test-retest and inter-rater reliability of AirBands in measuring AOP and its relationship with physical characteristics like thigh circumference and blood pressure.

Methods

The study involved 92 participants (46 females and 46 males; age = 23.3 ± 2.9 years, mass = 63.0 ± 8.8kg, thigh circumference = 51.5 ± 4.4cm) who had their AOP measured using both the Doppler ultrasound and AirBands. The order of measurement was randomized for each participant.

AOP was measured using the Doppler ultrasound by placing the cuff on the thigh and measuring the pedal pulse at the ankle. AOP was measured again three days later using only AirBands.

Validity was assessed by comparing the mean AOP measurements from both devices and calculating an Intraclass Correlation Coefficient (ICC). Inter-rater reliability for AOP measured using AirBands was determined by comparing measurements taken by two different clinicians and calculating the ICC. Test-retest reliability for AirBands was evaluated by comparing measurements taken on separate days using the ICC.

Key Findings

…AirBands demonstrated strong validity for measuring AOP in the lower limb…with ICCs ranging from 0.94 to 0.97, indicating excellent test-retest and inter-rater reliability…

Validity

AirBands vs. Doppler Ultrasound

AirBands demonstrated strong validity for measuring AOP in the lower limb when compared to Doppler ultrasound. The mean difference between the two methods was 4.1mmHg, representing a discrepancy of 2.1%.

Bland-Altman plot demonstrating the agreement between AOP measurements using AirBands and the Doppler ultrasound, highlighting the strong validity of AirBands. The dotted line represents ±1.96 standard deviations of the differences from the mean difference.

Reliability

AirBands: Session 1 vs. Session 2

The test-retest reliability of AirBands was found to be excellent. Measurements of AOP taken on the same subject by the same clinician, three days apart, showed a mean difference of just 0.6mmHg (0.3%), with an ICC of 0.94. This high ICC indicates a very low variation between the two sets of measurements.

Bland-Altman plot illustrating the consistency of AOP measurements taken by different clinicians using AirBands, showing excellent inter-rater reliability. The dotted line represents ±1.96 standard deviations of the differences from the mean difference.

AirBands also exhibited outstanding inter-rater reliability. When AOP measurements were taken on the same subject by two different clinicians, the ICC was 0.97, demonstrating a high level of consistency between different raters.

Bland-Altman plot depicting the consistency of AOP measurements taken on separate days with AirBands, underscoring the device's high test-retest reliability. The dotted line represents ±1.96 standard deviations of the differences from the mean difference.

Correlation Analysis

Impact of Blood Pressure and Thigh Circumference on AirBands

Thigh circumference showed a significant correlation with AOP (r = 0.53), indicating that larger thigh circumference is associated with higher AOP. Similarly, systolic blood pressure also had a significant positive correlation with AOP (r = 0.40). In contrast, diastolic blood pressure did not significantly correlate with AOP (p = 0.17).

The correlation analysis between AOP and key physical characteristics, including (A) the correlation between AOP and limb circumference, (B) the correlation between AOP and systolic blood pressure and (C) the correlation between AOP and diastolic blood pressure. Gray dots represent individual data points, the gray line is the regression line and the shaded area represents the confidence interval.

VALD’s Solution

The current study demonstrates that AirBands can measure AOP in the legs with high accuracy compared to the gold standard Doppler ultrasound. Additionally, the high test-retest reliability means it is an effective method to integrate BFR into rehabilitation and other long-term programs, allowing athletes and patients to optimize muscle growth and recovery post-injury. AirBands also ensure reliable AOP measurements across different clinicians, eliminating variability in the prescription of BFR.

AirBands streamline BFR training by automatically measuring AOP and enabling precise occlusion pressure prescriptions based on AOP during strength training. Controlled via the AirBands iOS or Android apps, clinicians can use AirBands to enhance the efficiency and accuracy of their training and rehabilitation protocols.

If you would like to know more about how to integrate VALD’s human measurement technology into your organization to help with the engagement of your clients, please reach out here.