Title: "Utilizing wearable NIRS technology for monitoring muscle oxygenation at home during physical activities of different intensities"

Date/Time: Tuesday, April 4, 2023 at 9:30 a.m.

Location: Zoom.  For link, contact Jasmine Dixon at jad324@pitt.edu

Abstract: Wearable fitness monitors are growing in popularity, with one in five Americans currently using devices. Typical monitors are limited to global estimates of activity. These devices do not directly measure local physiological changes within the muscles, which are influenced by intensity and duration. Near-infrared spectroscopy (NIRS) is a non-invasive technology that emits light into underlying tissue to measure muscle oxygenation (SmO2). SmO2 patterns during prolonged walking, a commonly prescribed exercise, have yet to be fully investigated. Purpose: To describe muscle oxygenation patterns during prescribed light and moderate-intensity walking in laboratory and at-home settings. An exploratory aim was included to examine free-living activities of similar intensity. Methods: Ten healthy participants (22.7 ± 2.11 years; 26.3 ± 1.87 kg/m2) completed a 1-hour light-intensity and moderate-intensity walk in laboratory and at-home. Intensity was monitored by the OMNI-RPE scale. SmO2 was recorded by a MOXY NIRS device on the participant’s dominant medial gastrocnemius muscle. Results: Medial gastrocnemius SmO2 increased after the start of walking. After 26.02 minutes of light-intensity walking, SmO2 reached a higher than resting plateau, ΔSmO2 = 24.53%, and remained elevated until the end of walking. In the lab, there were no significant differences between walking intensities. Prescribed at-home walking demonstrated similar SmO2 responses to laboratory walking. Individuals with higher self-reported amounts of walking had a different SmO2 response to walking with increased intensity. Muscle oxygenation responses to free-living activities depended on duration, intensity, and type of activity. MOXY NIRS had high usability scores among young, healthy adults. Conclusion: This study developed novel parameters to assess muscle oxygenation in response to prescribed walking. Additional physiological variables should be included in future work to better interpret muscle oxygenation patterns. Muscle oxygenation responses are impacted by duration, intensity, type of activity, training state of the muscle, and individual factors. Future research should examine their impact. Similarities in muscle oxygenation responses between settings promote the use of NIRS technology at-home. With advances in meaningful metrics, wearable NIRS will improve clinical health monitoring, inform exercise prescriptions and training, and provide valuable information on muscle health and performance.

Committee Chair: April J. Chambers, PhD, Associate Professor, Health and Human Development

Committee Members: Theodore J. Huppert, PhD, Associate Professor, Electrical and Computer Engineering, Elizabeth F. Nagle, PhD, Associate Co-Chair, Health and Human Development, and Mark S. Redfern, PhD, Interim Chair, Bioengineering