{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:22:44Z","timestamp":1760059364412,"version":"build-2065373602"},"reference-count":39,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2025,6,9]],"date-time":"2025-06-09T00:00:00Z","timestamp":1749427200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Research Ireland","award":["18\/FRL\/6188"],"award-info":[{"award-number":["18\/FRL\/6188"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This observational pilot study investigated neurocardiovascular responses to an active stand test using continuous physiological monitoring and functional data analysis (FDA) in older women. A sample of 25 community-dwelling female adults aged 59\u201378 years (mean age: 70.3 years) participated. Participants were dichotomized into comparison groups based on five factors: age (&lt;70 vs. \u226570 years); the presence of initial orthostatic hypotension (IOH, yes\/no); body mass index (BMI &lt; 25 vs. \u226525 kg\/m2); antihypertensive medication use (yes\/no); and physical frailty status assessed by the Survey of Health, Ageing and Retirement in Europe\u2014Frailty Instrument (SHARE-FI score &lt; \u22120.5 vs. \u2265\u22120.5). Each participant completed an active stand test during which six physiological signals were continuously recorded: systolic (sBP) and diastolic (dBP) blood pressure and heart rate (HR) via digital artery photoplethysmography and left frontal oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and tissue saturation index (TSI) via near-infrared spectroscopy (NIRS). The signal analysis focused on a standardized 200 s window spanning 50 s before to 150 s after the stand, with all signals resampled and synchronized at 5 Hz. FDA was used to statistically compare the full time series between groups for each signal. Group-level differences revealed that younger participants (&lt;70 years) exhibited significantly higher HR in multiple periods following the stand (~10 s, ~30 s, ~90 s, and ~140 s post-stand) compared to their older counterparts. Participants with IOH demonstrated significantly lower sBP at ~10 s, ~80 s, and ~130 s post-stand and lower dBP at ~10 s post-stand. Among participants classified as overweight\/obese (BMI \u2265 25 kg\/m2), significantly lower levels of HHb were observed at ~10 s, ~30\u201350 s, and ~60 s post-stand, while O2Hb levels were reduced at ~50 s, ~60 s, ~70\u2013110 s, ~130 s, and ~140 s post-stand. No statistically significant group-level differences were observed based on antihypertensive medication use or frailty status. These findings demonstrate the utility of FDA in detecting subtle, time-dependent physiological variations during orthostatic challenge and underscore the value of continuous neurocardiovascular monitoring in assessing orthostatic tolerance in aging populations.<\/jats:p>","DOI":"10.3390\/s25123616","type":"journal-article","created":{"date-parts":[[2025,6,9]],"date-time":"2025-06-09T05:54:05Z","timestamp":1749448445000},"page":"3616","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Characterizing Neurocardiovascular Responses to an Active Stand Test in Older Women: A Pilot Study Using Functional Data Analysis"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8217-0550","authenticated-orcid":false,"given":"Feng","family":"Xue","sequence":"first","affiliation":[{"name":"Discipline of Medical Gerontology, School of Medicine, Trinity College Dublin, D02 PN40 Dublin, Ireland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3882-7447","authenticated-orcid":false,"given":"Roman","family":"Romero-Ortuno","sequence":"additional","affiliation":[{"name":"Discipline of Medical Gerontology, School of Medicine, Trinity College Dublin, D02 PN40 Dublin, Ireland"},{"name":"Falls and Syncope Unit, Mercer\u2019s Institute for Successful Ageing, St James\u2019s Hospital, D08 NHY1 Dublin, Ireland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"655","DOI":"10.1111\/j.1532-5415.2011.03352.x","article-title":"Continuous noninvasive orthostatic blood pressure measurements and their relationship with orthostatic intolerance, falls, and frailty in older people","volume":"59","author":"Cogan","year":"2011","journal-title":"J. Am. Geriatr. Soc."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"100071","DOI":"10.1016\/j.ijchy.2020.100071","article-title":"Initial orthostatic hypotension and orthostatic intolerance symptom prevalence in older adults: A systematic review","volume":"8","author":"Christopoulos","year":"2021","journal-title":"Int. J. Cardiol. Hypertens."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1007\/s10286-013-0222-x","article-title":"Elevated resting heart rate and reduced orthostatic tolerance in obese humans","volume":"24","author":"Lee","year":"2014","journal-title":"Clin. Auton. Res."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Goswami, N., Blaber, A.P., Hinghofer-Szalkay, H., and Montani, J.P. (2017). Orthostatic Intolerance in Older Persons: Etiology and Countermeasures. Front. Physiol., 8.","DOI":"10.3389\/fphys.2017.00803"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"675","DOI":"10.1007\/s41999-022-00618-4","article-title":"Orthostatic intolerance: A frailty marker for older adults","volume":"13","author":"Kahyaoglu","year":"2022","journal-title":"Eur. Geriatr. Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"102756","DOI":"10.1016\/j.autneu.2020.102756","article-title":"Systemic and cerebral circulatory adjustment within the first 60 s after active standing: An integrative physiological view","volume":"231","author":"Harms","year":"2021","journal-title":"Auton. Neurosci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1042\/CS20060091","article-title":"Initial orthostatic hypotension: Review of a forgotten condition","volume":"112","author":"Wieling","year":"2007","journal-title":"Clin. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1520","DOI":"10.1093\/ageing\/afab090","article-title":"Prevalence of initial orthostatic hypotension in older adults: A systematic review and meta-analysis","volume":"50","author":"Tran","year":"2021","journal-title":"Age Ageing"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Xue, F., Monaghan, A., Jennings, G., Byrne, L., Foran, T., Duggan, E., and Romero-Ortuno, R. (2022). A Novel Methodology for the Synchronous Collection and Multimodal Visualization of Continuous Neurocardiovascular and Neuromuscular Physiological Data in Adults with Long COVID. Sensors, 22.","DOI":"10.3390\/s22051758"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Xue, F., Knight, S., Connolly, E., O\u2019Halloran, A., Shirsath, M.A., Newman, L., Duggan, E., Kenny, R.A., and Romero-Ortuno, R. (2024). Were Frailty Identification Criteria Created Equal? A Comparative Case Study on Continuous Non-Invasively Collected Neurocardiovascular Signals during an Active Standing Test in the Irish Longitudinal Study on Ageing (TILDA). Sensors, 24.","DOI":"10.3390\/s24020442"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Gertheiss, J., Rugamer, D., Liew, B.X.W., and Greven, S. (2024). Functional Data Analysis: An Introduction and Recent Developments. Biom. J., 66.","DOI":"10.1002\/bimj.202300363"},{"key":"ref_12","unstructured":"Duggan, E. (2024). Sarcopenia and Orthostatic Hypotension: Investigating the Underlying Haemodynamics. [Ph.D. Thesis, Trinity College Dublin, School of Medicine, Discipline of Medical Gerontology]. Available online: https:\/\/www.tara.tcd.ie\/handle\/2262\/110507."},{"key":"ref_13","unstructured":"WHO (2025, May 04). Obesity. Available online: https:\/\/www.who.int\/health-topics\/obesity."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Romero-Ortuno, R., Walsh, C.D., Lawlor, B.A., and Kenny, R.A. (2010). A frailty instrument for primary care: Findings from the Survey of Health, Ageing and Retirement in Europe (SHARE). BMC Geriatr., 10.","DOI":"10.1186\/1471-2318-10-57"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"3924508","DOI":"10.1155\/2019\/3924508","article-title":"Current Status and Prospects of Health-Related Sensing Technology in Wearable Devices","volume":"2019","author":"Cho","year":"2019","journal-title":"J. Healthc. Eng."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"647","DOI":"10.1161\/01.HYP.13.6.647","article-title":"Comparison of finger and intra-arterial blood pressure monitoring at rest and during laboratory testing","volume":"13 Pt 1","author":"Parati","year":"1989","journal-title":"Hypertension"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1038\/sj.jhh.1001639","article-title":"Validation of the Finometer device for measurement of blood pressure in black women","volume":"18","author":"Schutte","year":"2004","journal-title":"J. Hum. Hypertens."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"921","DOI":"10.1016\/j.neuroimage.2012.03.049","article-title":"A brief review on the history of human functional near-infrared spectroscopy (fNIRS) development and fields of application","volume":"63","author":"Ferrari","year":"2012","journal-title":"Neuroimage"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"6","DOI":"10.1016\/j.neuroimage.2013.05.004","article-title":"A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology","volume":"85","author":"Scholkmann","year":"2014","journal-title":"Neuroimage"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Cortese, L., Zanoletti, M., Karadeniz, U., Pagliazzi, M., Yaqub, M.A., Busch, D.R., Mesquida, J., and Durduran, T. (2021). Performance Assessment of a Commercial Continuous-Wave Near-Infrared Spectroscopy Tissue Oximeter for Suitability for Use in an International, Multi-Center Clinical Trial. Sensors, 21.","DOI":"10.3390\/s21216957"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2117","DOI":"10.1364\/BOE.10.002117","article-title":"Quantitative measurements of cerebral blood flow with near-infrared spectroscopy","volume":"10","author":"Pham","year":"2019","journal-title":"Biomed. Opt. Express"},{"key":"ref_22","first-page":"4577","article-title":"The use of near-infrared spectroscopy in understanding skeletal muscle physiology: Recent developments","volume":"369","author":"Ferrari","year":"2011","journal-title":"Philos. Trans. A Math. Phys. Eng. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.neuroimage.2013.11.033","article-title":"Twenty years of functional near-infrared spectroscopy: Introduction for the special issue","volume":"85 Pt 1","author":"Boas","year":"2014","journal-title":"Neuroimage"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"103988","DOI":"10.1016\/j.archger.2019.103988","article-title":"Age and sex differences in frontal lobe cerebral oxygenation in older adults-Normative values using novel, scalable technology: Findings from the Irish Longitudinal Study on Ageing (TILDA)","volume":"87","author":"Newman","year":"2020","journal-title":"Arch. Gerontol. Geriatr."},{"key":"ref_25","first-page":"3","article-title":"The ten-twenty electrode system of the International Federation. The International Federation of Clinical Neurophysiology","volume":"52","author":"Klem","year":"1999","journal-title":"Electroencephalogr. Clin. Neurophysiol. Suppl."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Ramsay, J.O., and Silverman, B.W. (2002). Applied Functional Data Analysis: Methods and Case Studies, Springer.","DOI":"10.1007\/b98886"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Ullah, S., and Finch, C. (2013). Applications of functional data analysis: A systematic review. BMC Med. Res. Methodol., 13.","DOI":"10.1186\/1471-2288-13-43"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Ramsay, J., and Silverman, B.W. (2005). Functional Data Analysis, Springer.","DOI":"10.1007\/b98888"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1007\/BF00283745","article-title":"Reflex control of heart rate in normal subjects in relation to age: A data base for cardiac vagal neuropathy","volume":"22","author":"Wieling","year":"1982","journal-title":"Diabetologia"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1042\/cs0720335","article-title":"Circulatory response to postural change in healthy male subjects in relation to age","volume":"72","author":"Dambrink","year":"1987","journal-title":"Clin. Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1780","DOI":"10.1161\/CIRCULATIONAHA.114.009831","article-title":"Age-related normative changes in phasic orthostatic blood pressure in a large population study: Findings from The Irish Longitudinal Study on Ageing (TILDA)","volume":"130","author":"Finucane","year":"2014","journal-title":"Circulation"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/j.neurobiolaging.2021.04.008","article-title":"Obesity is associated with reduced cerebral blood flow\u2014Modified by physical activity","volume":"105","author":"Knight","year":"2021","journal-title":"Neurobiol. Aging"},{"key":"ref_33","unstructured":"Klop, M. (2025). Rise & Shine: Capturing Postural Cerebral Oxygenation and Blood Pressure Changes with Nearinfrared Light. [Ph.D. Dissertation, Radboud University]. Available online: https:\/\/repository.ubn.ru.nl\/handle\/2066\/317914."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"6331","DOI":"10.1007\/s11357-024-01241-w","article-title":"Home-based monitoring of cerebral oxygenation in response to postural changes using near-infrared spectroscopy","volume":"46","author":"Klop","year":"2024","journal-title":"Geroscience"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"(1996). Consensus statement on the definition of orthostatic hypotension, pure autonomic failure, and multiple system atrophy. The Consensus Committee of the American Autonomic Society and the American Academy of Neurology. Neurology, 46, 1470.","DOI":"10.1212\/WNL.46.5.1470"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1159\/000450642","article-title":"Standing Up Slowly Antagonises Initial Blood Pressure Decrease in Older Adults with Orthostatic Hypotension","volume":"63","author":"Reijnierse","year":"2017","journal-title":"Gerontology"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"685","DOI":"10.1007\/s10286-021-00833-2","article-title":"Diagnostic criteria for initial orthostatic hypotension: A narrative review","volume":"31","author":"Harms","year":"2021","journal-title":"Clin. Auton. Res."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1491","DOI":"10.1111\/jch.14588","article-title":"Influencing factors and hemodynamic study of initial and sustained orthostatic hypotension in middle-aged and elderly patients","volume":"24","author":"Hui","year":"2022","journal-title":"J. Clin. Hypertens."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1993","DOI":"10.1161\/HYPERTENSIONAHA.123.21537","article-title":"Orthostatic Hypertension: A Newcomer Among the Hypertension Phenotypes","volume":"80","author":"Palatini","year":"2023","journal-title":"Hypertension"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/25\/12\/3616\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:48:47Z","timestamp":1760032127000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/25\/12\/3616"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,6,9]]},"references-count":39,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2025,6]]}},"alternative-id":["s25123616"],"URL":"https:\/\/doi.org\/10.3390\/s25123616","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2025,6,9]]}}}