{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T15:03:45Z","timestamp":1791644625180,"version":"4.3.4"},"reference-count":44,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2025,7,31]],"date-time":"2025-07-31T00:00:00Z","timestamp":1753920000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["J cachexia sarcopenia muscle"],"published-print":{"date-parts":[[2025,8]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Orthostatic hypotension (OH) is a prevalent condition among older adults, characterised by a sudden drop in blood pressure upon standing, often leading to dizziness and increased risk of falls, morbidity and mortality. The skeletal muscle pump is thought to be important in maintaining venous return and stabilising blood pressure during postural changes, especially during the performance of physical counterpressure manoeuvres (PCMs). This study investigated the temporal relationships between thigh muscle activation, thigh haemoglobin concentration and cardiovascular parameters (heart rate [HR], stroke volume [SV] and total peripheral resistance [TPR]) to understand the muscle pump's role in haemodynamic regulation while performing supine and standing PCMs.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Twenty\u2010two participants (mean age 70.4\u2009\u00b1\u20095.2\u2009years) were assessed at the Falls and Syncope Unit at St. James's Hospital, Dublin, Ireland. Each underwent an active stand test, around which participants were asked to squeeze their thigh muscles as hard as possible for 10\u2009s, firstly while in the supine position, and secondly after standing. Surface electromyography (EMG), near\u2010infrared spectroscopy (NIRS) and non\u2010invasive digital artery photoplethysmography were used to continuously monitor thigh muscle activation, muscle haemoglobin concentration and cardiovascular function, respectively. Cross\u2010correlation and Granger causality analyses were conducted to determine the temporal and causal relationships between the signals.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Cross\u2010correlation analysis revealed significant temporal relationships between muscle activation and cardiovascular parameters during PCMs. Specifically, HR, TPR and SV lagged EMG by approximately 1\u20133, 6\u20139 and 8\u201310\u2009s, respectively. Mean peak cross\u2010correlation coefficients during the standing PCM were 0.609 for EMG to HR, 0.516 for EMG to TPR and 0.564 for EMG to SV. Granger causality tests indicated that muscle activation significantly predicted changes in SV, HR and TPR, with causality proportions increasing during PCMs (e.g., SV to EMG: 9.1% during supine rest; EMG to SV: 63.6% during standing PCM). Notably, inter\u2010individual variability was observed, with peak CCs for EMG to SV ranging from 0.251 to 0.849, and lag times from \u221221.9 to 13.4\u2009s during standing PCM.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>These findings underscore the role of the skeletal muscle pump in modulating venous return and cardiac output during PCMs. The study provides a novel methodological framework for assessing skeletal muscle pump function and its impact on cardiovascular dynamics. By understanding the temporal interplay between muscle activation and cardiovascular responses, we can develop effective strategies to improve cardiovascular stability and potentially prevent OH. Future research should validate these findings in larger, more diverse cohorts and explore long\u2010term adaptations to targeted interventions.<\/jats:p><\/jats:sec>","DOI":"10.1002\/jcsm.70019","type":"journal-article","created":{"date-parts":[[2025,7,31]],"date-time":"2025-07-31T10:30:46Z","timestamp":1753957846000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Assessing the Skeletal Muscle Pump During Lower Limb Counterpressure: Lags and Causality in Cardiovascular Regulation"],"prefix":"10.1002","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1245-4870","authenticated-orcid":false,"given":"Silvin\u00a0P.","family":"Knight","sequence":"first","affiliation":[{"name":"FRAILMatics Research Group, Discipline of Medical Gerontology, School of Medicine Trinity College Dublin  Dublin Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8490-2076","authenticated-orcid":false,"given":"Eoin","family":"Duggan","sequence":"additional","affiliation":[{"name":"FRAILMatics Research Group, Discipline of Medical Gerontology, School of Medicine Trinity College Dublin  Dublin Ireland"},{"name":"Falls and Syncope Unit (FASU), Mercer\u2019s Institute for Successful Ageing (MISA), St James\u2019s Hospital  Dublin Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8217-0550","authenticated-orcid":false,"given":"Feng","family":"Xue","sequence":"additional","affiliation":[{"name":"FRAILMatics Research Group, Discipline of Medical Gerontology, School of Medicine Trinity College Dublin  Dublin Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3882-7447","authenticated-orcid":false,"given":"Roman","family":"Romero\u2010Ortuno","sequence":"additional","affiliation":[{"name":"FRAILMatics Research Group, Discipline of Medical Gerontology, School of Medicine Trinity College Dublin  Dublin Ireland"},{"name":"Falls and Syncope Unit (FASU), Mercer\u2019s Institute for Successful Ageing (MISA), St James\u2019s Hospital  Dublin Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,7,31]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jamda.2018.11.003"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1111\/joim.12249"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.1897.sp000657"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1093\/ptj\/29.1.12"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1177\/10597123030111002"},{"key":"e_1_2_8_7_1","volume-title":"The Effect of Exercise on the Cardio\u2010Postural Relationship","author":"Bruner M.","year":"2012"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1093\/oso\/9780195073621.001.0001"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1038\/srep45301"},{"key":"e_1_2_8_10_1","doi-asserted-by":"publisher","DOI":"10.3389\/fcvm.2022.1016420"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.3389\/fcvm.2023.1040036"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.01172.2012"},{"key":"e_1_2_8_13_1","volume-title":"Modern Mathematics for Engineers","author":"Wiener N.","year":"1956"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.2307\/1912791"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.neuroimage.2010.02.059"},{"key":"e_1_2_8_16_1","doi-asserted-by":"publisher","DOI":"10.1002\/9783527609970.ch17"},{"key":"e_1_2_8_17_1","doi-asserted-by":"publisher","DOI":"10.1007\/s10439-008-9441-z"},{"key":"e_1_2_8_18_1","doi-asserted-by":"publisher","DOI":"10.1098\/rsta.2012.0161"},{"key":"e_1_2_8_19_1","doi-asserted-by":"publisher","DOI":"10.1109\/JPROC.2015.2476824"},{"key":"e_1_2_8_20_1","first-page":"29","volume-title":"2016 Computing in Cardiology Conference (CinC)","author":"Verma A. K.","year":"2016"},{"key":"e_1_2_8_21_1","doi-asserted-by":"publisher","DOI":"10.1109\/EIT.2016.7535312"},{"key":"e_1_2_8_22_1","doi-asserted-by":"publisher","DOI":"10.1109\/EMBC.2016.7591194"},{"key":"e_1_2_8_23_1","doi-asserted-by":"publisher","DOI":"10.3389\/fphys.2019.00845"},{"key":"e_1_2_8_24_1","doi-asserted-by":"publisher","DOI":"10.1016\/S1050-6411(00)00027-4"},{"key":"e_1_2_8_25_1","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.00171.2014"},{"key":"e_1_2_8_26_1","doi-asserted-by":"publisher","DOI":"10.2307\/2286348"},{"key":"e_1_2_8_27_1","doi-asserted-by":"publisher","DOI":"10.1016\/0304-4076(92)90104-Y"},{"key":"e_1_2_8_28_1","doi-asserted-by":"publisher","DOI":"10.1097\/NNR.0000000000000193"},{"key":"e_1_2_8_29_1","doi-asserted-by":"publisher","DOI":"10.1016\/0304-4076(94)01616-8"},{"key":"e_1_2_8_30_1","doi-asserted-by":"publisher","DOI":"10.1093\/cvr\/7.4.528"},{"key":"e_1_2_8_31_1","doi-asserted-by":"publisher","DOI":"10.1186\/cc6975"},{"key":"e_1_2_8_32_1","doi-asserted-by":"publisher","DOI":"10.1152\/advan.00182.2018"},{"key":"e_1_2_8_33_1","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.ph.45.030183.001305"},{"key":"e_1_2_8_34_1","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.2001.013486"},{"key":"e_1_2_8_35_1","doi-asserted-by":"publisher","DOI":"10.1042\/CS20070064"},{"key":"e_1_2_8_36_1","doi-asserted-by":"publisher","DOI":"10.1161\/01.RES.76.1.127"},{"key":"e_1_2_8_37_1","volume-title":"StatPearls [Internet]","author":"Chaudhry R.","year":"2022"},{"key":"e_1_2_8_38_1","doi-asserted-by":"publisher","DOI":"10.3390\/jcm13010018"},{"key":"e_1_2_8_39_1","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.2003.057133"},{"key":"e_1_2_8_40_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.eclinm.2021.101264"},{"key":"e_1_2_8_41_1","doi-asserted-by":"publisher","DOI":"10.3389\/fmed.2021.755705"},{"key":"e_1_2_8_42_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.eupc.2004.03.008"},{"key":"e_1_2_8_43_1","doi-asserted-by":"publisher","DOI":"10.1016\/0008-6363(96)00116-2"},{"key":"e_1_2_8_44_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jacc.2006.06.059"},{"key":"e_1_2_8_45_1","doi-asserted-by":"publisher","DOI":"10.1093\/europace\/euu125"}],"container-title":["Journal of Cachexia, Sarcopenia and Muscle"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/jcsm.70019","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,8,22]],"date-time":"2025-08-22T07:47:19Z","timestamp":1755848839000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/jcsm.70019"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,7,31]]},"references-count":44,"journal-issue":{"issue":"4","published-print":{"date-parts":[[2025,8]]}},"alternative-id":["10.1002\/jcsm.70019"],"URL":"https:\/\/doi.org\/10.1002\/jcsm.70019","archive":["Portico"],"relation":{},"ISSN":["2190-5991","2190-6009"],"issn-type":[{"value":"2190-5991","type":"print"},{"value":"2190-6009","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,7,31]]},"assertion":[{"value":"2024-08-23","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-06-14","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-07-31","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e70019"}}