{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T21:35:31Z","timestamp":1778276131295,"version":"3.51.4"},"reference-count":58,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2020,9,5]],"date-time":"2020-09-05T00:00:00Z","timestamp":1599264000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Heart rate (HR) as an important physiological indicator could properly describe global subject\u2019s physical status. Photoplethysmographic (PPG) sensors are catching on in field of wearable sensors, combining the advantages in costs, weight and size. Nevertheless, accuracy in HR readings is unreliable specifically during physical activity. Among several identified sources that affect PPG recording, contact pressure (CP) between the PPG sensor and skin greatly influences the signals. Methods: In this study, the accuracy of HR measurements of a PPG sensor at different CP was investigated when compared with a commercial ECG-based chest strap used as a test control, with the aim of determining the optimal CP to produce a reliable signal during physical activity. Seventeen subjects were enrolled for the study to perform a physical activity at three different rates repeated at three different contact pressures of the PPG-based wristband. Results: The results show that the CP of 54 mmHg provides the most accurate outcome with a Pearson correlation coefficient ranging from 0.81 to 0.95 and a mean average percentage error ranging from 3.8% to 2.4%, based on the physical activity rate. Conclusion: Authors found that changes in the CP have greater effects on PPG-HR signal quality than those deriving from the intensity of the physical activity and specifically, the individual best CP for each subject provided reliable HR measurements even for a high intensity of physical exercise with a Bland\u2013Altman plot within \u00b111 bpm. Although future studies on a larger cohort of subjects are still needed, this study could contribute a profitable indication to enhance accuracy of PPG-based wearable devices.<\/jats:p>","DOI":"10.3390\/s20185052","type":"journal-article","created":{"date-parts":[[2020,9,6]],"date-time":"2020-09-06T23:12:49Z","timestamp":1599433969000},"page":"5052","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":62,"title":["A Study on the Effect of Contact Pressure during Physical Activity on Photoplethysmographic Heart Rate Measurements"],"prefix":"10.3390","volume":"20","author":[{"given":"Francesco","family":"Scardulla","sequence":"first","affiliation":[{"name":"Department of Engineering, University of Palermo, 90128 Palermo, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4837-1797","authenticated-orcid":false,"given":"Leonardo","family":"D\u2019Acquisto","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Palermo, 90128 Palermo, Italy"}]},{"given":"Raffaele","family":"Colombarini","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Palermo, 90128 Palermo, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9637-4730","authenticated-orcid":false,"given":"Sijung","family":"Hu","sequence":"additional","affiliation":[{"name":"Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4841-2560","authenticated-orcid":false,"given":"Salvatore","family":"Pasta","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Palermo, 90128 Palermo, Italy"}]},{"given":"Diego","family":"Bellavia","sequence":"additional","affiliation":[{"name":"Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS-ISMETT, via Tricomi n.5, 90127 Palermo, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2020,9,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1145\/2629633","article-title":"Wearables: Has The age of smartwatches finally arrived?","volume":"58","author":"Rawassizadeh","year":"2015","journal-title":"Commun. 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