Reducing Arterial Stiffness with a Smart Ring and AI-Guided Exercise

This is a single-site, 12-week randomized, controlled trial (RCT) consisting of three groups (N = 55 per group):

• The Oura Ring (a control group)
• The Oura Ring + Supervised high-intensity interval training (HIIT) twice a week
• The Oura Ring + AI-based Coaching for steady-state aerobic training (no external supervision)

Exercise modalities are selected based on hypothesized long-term sustainability and expected cardiorespiratory outcomes. The HIIT protocol has been tested in previous studies and found to be effective in improving VO2max; but it is unlikely to be sustainable in the long-term. Thus, in this study we compare the HIIT protocol to individualized, steady-state ("Zone 2") exercise guidance provided by AI.

Participants will be recruited via e-mail and newspaper ads from the region of Kuopio, Finland. All groups will be blinded to their CVA/PWV information but will use identical Rings. Apart from the AI coach -group, Oura Ring App experiences will also be identical. The study consists of four (4) visits.

The study site is Kuopio Institute for Exercise Medicine, Kuopio, Finland. Participants will be provided materials for an informed consent prior to participation. Eligible participants who have provided a written consent will be invited for the first baseline measurement (Visit 1) where they will be provided Oura Rings and given instructions for using it, and their VO2max is measured. The next baseline measurement (Visit 2) is scheduled for two weeks which is the time the Ring needs to calibrate its Cardiovascular Age and pulse-wave velocity (PWV) estimates. At the second baseline measurement, the participants' PWV is recorded with a reference device and their body composition is also measured. Following these measurements, they are immediately randomized to one of the three study groups and given written and oral instructions specific to their allocation. After 12 weeks, the participant is invited for a repeated VO2max measurement (Visit 3), followed by final PWV and body composition measurements (Visit 4) within the same week. Measurements are not conducted on the same days due to fasting requirements for PWV, and interfering effect of VO2max testing on PWV.

Inclusion criteria

• Self-reported moderate intensity physical activity less than 2 hours 30 minutes per week or vigorous intensity physical activity less than 1 hour 15 minutes per week.

Exclusion criteria

• Coronary artery disease (or other chronic condition preventing safe participation in an exercise intervention), diabetes and moderate/severe hypertension diagnosed by a physician. Inability to use the Oura Ring for some reason (e.g. work-related restrictions) is also considered as exclusion criteria; however, short interruptions (e.g. 1-2 hour work tasks without ring) are possible.