{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T07:15:41Z","timestamp":1778570141550,"version":"3.51.4"},"reference-count":30,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2025,6,10]],"date-time":"2025-06-10T00:00:00Z","timestamp":1749513600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100014064","name":"Salamanca City Council\u2014University of Salamanca","doi-asserted-by":"publisher","award":["L9AB"],"award-info":[{"award-number":["L9AB"]}],"id":[{"id":"10.13039\/501100014064","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100014064","name":"Salamanca City Council\u2014University of Salamanca","doi-asserted-by":"publisher","award":["INV2024-47"],"award-info":[{"award-number":["INV2024-47"]}],"id":[{"id":"10.13039\/501100014064","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Professional Association of Physiotherapists of Castilla y Le\u00f3n","award":["L9AB"],"award-info":[{"award-number":["L9AB"]}]},{"name":"Professional Association of Physiotherapists of Castilla y Le\u00f3n","award":["INV2024-47"],"award-info":[{"award-number":["INV2024-47"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background\/Objectives: Lower-limb muscle function is traditionally assessed with tests like the five times sit-to-stand test (5STS) and the 30-s chair stand test (30CS). The ADR Encoder, a linear transducer, measures power and velocity during the sit-to-stand test. This study aimed to validate its use as functional indicators of muscle function in older adults. Methods: A cross-sectional study with 114 participants (mean age: 72.92 \u00b1 4.97 years) was conducted. The 5STS, 30CS, power, and speed were measured using the ADR Encoder. Participants were categorized into frail, pre-frail, and robust groups according to the FRAIL Scale. Criterion, intraobserver, and interobserver validity were assessed. Results: Strong correlations (r &gt; 0.7; p &lt; 0.001) were found between power, speed, and both 5STS and 30CS. The interobserver intraclass correlation coefficient (ICC) for speed was 0.90 and the intraobserver ICC was 0.85. For power, the interobserver ICC was 0.88 and the intraobserver ICC was 0.79, all statistically significant (p &lt; 0.001). Significant differences in power (7.78 W vs. 11.26 W; p &lt; 0.001) and speed (0.40 m\/s vs. 0.58 m\/s; p &lt; 0.001) were observed between frail and non-frail participants. Conclusions: The ADR Encoder is a valid, reliable tool for measuring power and speed in older adults. Its strong correlations with the 5STS and 30CS demonstrate its clinical relevance, with high reproducibility across observers and time points. Its application in diverse clinical and community settings could broaden its utility in geriatric functional assessment.<\/jats:p>","DOI":"10.3390\/diagnostics15121475","type":"journal-article","created":{"date-parts":[[2025,6,10]],"date-time":"2025-06-10T09:59:14Z","timestamp":1749549554000},"page":"1475","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Reliability and Validity of the Linear Transducer \u201cADR Encoder\u201d for Measuring Power and Speed of the Sit-to-Stand Tests in Older Adults"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8349-0441","authenticated-orcid":false,"given":"Luis","family":"Polo-Ferrero","sequence":"first","affiliation":[{"name":"Department of Nursing and Physiotherapy, University of Salamanca, 37007 Salamanca, Spain"},{"name":"Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2730-3242","authenticated-orcid":false,"given":"Mar\u00eda Luz","family":"S\u00e1nchez-Tocino","sequence":"additional","affiliation":[{"name":"Department of Nursing and Physiotherapy, University of Salamanca, 37007 Salamanca, Spain"},{"name":"Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Arturo","family":"D\u00e1vila-Marcos","sequence":"additional","affiliation":[{"name":"Department of Nursing and Physiotherapy, University of Salamanca, 37007 Salamanca, Spain"},{"name":"Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marta Beatriz","family":"Carrera-Villegas","sequence":"additional","affiliation":[{"name":"Department of Nursing and Physiotherapy, University of Salamanca, 37007 Salamanca, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7391-4394","authenticated-orcid":false,"given":"Mar\u00eda Carmen","family":"S\u00e1nchez-S\u00e1nchez","sequence":"additional","affiliation":[{"name":"Department of Nursing and Physiotherapy, University of Salamanca, 37007 Salamanca, Spain"},{"name":"Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4486-4076","authenticated-orcid":false,"given":"Roberto","family":"M\u00e9ndez-S\u00e1nchez","sequence":"additional","affiliation":[{"name":"Department of Nursing and Physiotherapy, University of Salamanca, 37007 Salamanca, Spain"},{"name":"Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.12968\/hmed.2019.0377","article-title":"Global ageing: Successes, challenges and opportunities","volume":"81","author":"Mitchell","year":"2020","journal-title":"Br. J. Hosp. Med."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1365","DOI":"10.1016\/S0140-6736(19)31786-6","article-title":"Frailty: Implications for clinical practice and public health","volume":"394","author":"Hoogendijk","year":"2019","journal-title":"Lancet"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"M146","DOI":"10.1093\/gerona\/56.3.M146","article-title":"Frailty in older adults: Evidence for a phenotype","volume":"56","author":"Fried","year":"2001","journal-title":"J. Gerontol. A Biol. Sci. Med. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"102395","DOI":"10.1016\/j.aprim.2022.102395","article-title":"Fragilidad en atenci\u00f3n primaria: Diagn\u00f3stico y manejo multidisciplinar","volume":"54","year":"2022","journal-title":"Aten. Primaria"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"735","DOI":"10.3233\/BMR-181283","article-title":"Assessment of the musculoskeletal performance with squat tests and performance-oriented measurements in older adults","volume":"33","author":"Uysal","year":"2020","journal-title":"J. Back Musculoskelet. Rehabil."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1007\/BF03325265","article-title":"The five-times-sit-to-stand test: Validity, reliability and detectable change in older females","volume":"24","author":"Goldberg","year":"2012","journal-title":"Aging Clin. Exp. Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1080\/02701367.1999.10608028","article-title":"A 30-s chair-stand test as a measure of lower body strength in community-residing older adults","volume":"70","author":"Jones","year":"1999","journal-title":"Res. Q. Exerc. Sport"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1186\/s11556-022-00297-x","article-title":"Effectiveness of power training compared to strength training in older adults: A systematic review and meta-analysis","volume":"19","author":"Kiers","year":"2022","journal-title":"Eur. Rev. Aging Phys. Act."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"371","DOI":"10.1093\/ageing\/23.5.371","article-title":"Strength, power and related functional ability of healthy people aged 65-89 years","volume":"23","author":"Skelton","year":"1994","journal-title":"Age Ageing"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Lopez-Torres, O., Fernandez-Elias, V.E., Li, J., Gomez-Ruano, M.A., and Guadalupe-Grau, A. Validity and Reliability of A New Low-Cost Linear Position Transducer to Measure Mean Propulsive Velocity: The ADR device. Proc. Inst. Mech. Eng. P J. Sports Eng. Technol., 2022.","DOI":"10.1177\/17543371221104345"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1016\/j.exger.2018.08.006","article-title":"The sit-to-stand muscle power test: An easy, inexpensive and portable procedure to assess muscle power in older people","volume":"112","author":"Alcazar","year":"2018","journal-title":"Exp. Gerontol."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Alcazar, J., Kamper, R.S., Aagaard, P., Haddock, B., Prescott, E., Ara, I., and Suetta, C. (2020). Relation between leg extension power and 30-s sit-to-stand muscle power in older adults: Validation and translation to functional performance. Sci. Rep., 10.","DOI":"10.1038\/s41598-020-73395-4"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"298","DOI":"10.1016\/j.physio.2014.12.005","article-title":"Validity of linear encoder measurement of sit-to-stand performance power in older people","volume":"101","author":"Lindemann","year":"2015","journal-title":"Physiotherapy"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Balachandran, A.T., Orange, S.T., Wang, Y., Lustin, R., Vega, A., and Quiles, N. (2024). Comparison of two popular transducers to measure sit-to-stand power in older adults. PLoS ONE, 19.","DOI":"10.1371\/journal.pone.0308808"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1016\/j.gaitpost.2019.12.003","article-title":"Validity of various portable devices to measure sit-to-stand velocity and power in older adults","volume":"76","author":"Orange","year":"2020","journal-title":"Gait Posture"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.ijsu.2011.10.001","article-title":"CONSORT 2010 explanation and elaboration: Updated guidelines for reporting parallel group randomised trials","volume":"10","author":"Moher","year":"2012","journal-title":"Int. J. Surg."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2191","DOI":"10.1001\/jama.2013.281053","article-title":"World Medical Association Declaration of Helsinki: Ethical Principles for Medical Research Involving Human Subjects","volume":"310","author":"Association","year":"2013","journal-title":"JAMA"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1093\/gerona\/59.3.M255","article-title":"Untangling the concepts of disability, frailty, and comorbidity: Implications for improved targeting and care","volume":"59","author":"Fried","year":"2004","journal-title":"J. Gerontol. A Biol. Sci. Med. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1018","DOI":"10.1002\/pmrj.12850","article-title":"Calculating sample size for reliability studies","volume":"14","author":"Borg","year":"2022","journal-title":"PM&R"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Cohen, J. (2013). Statistical Power Analysis for the Behavioral Sciences, Routledge. [2nd ed.].","DOI":"10.4324\/9780203771587"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1177\/001316446002000104","article-title":"A Coefficient of Agreement for Nominal Scales","volume":"20","author":"Cohen","year":"1960","journal-title":"Educ. Psychol. Meas."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"4","DOI":"10.1097\/JES.0b013e31823b5f13","article-title":"Skeletal muscle power: A critical determinant of physical functioning in older adults","volume":"40","author":"Reid","year":"2012","journal-title":"Exerc. Sport Sci. Rev."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"728","DOI":"10.1093\/gerona\/58.8.M728","article-title":"A comparison of leg power and leg strength within the InCHIANTI study: Which influences mobility more?","volume":"58","author":"Bean","year":"2003","journal-title":"J. Gerontol. A Biol. Sci. Med. Sci."},{"key":"ref_24","first-page":"27","article-title":"The Five Times Sit-to-Stand Test: Safety and reliability with older intensive care unit patients at discharge","volume":"31","author":"Duarte","year":"2019","journal-title":"Rev. Bras. Ter. Intensiva"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1016\/j.gaitpost.2017.10.029","article-title":"Validity and reliability of an iPhone App to assess time, velocity and leg power during a sit-to-stand functional performance test","volume":"59","author":"Smart","year":"2018","journal-title":"Gait Posture"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1093\/ageing\/32.3.315","article-title":"Identifying a cut-off point for normal mobility: A comparison of the timed \u201cup and go\u201d test in community-dwelling and institutionalised elderly women","volume":"32","author":"Bischoff","year":"2003","journal-title":"Age Ageing"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Pavasini, R., Guralnik, J., Brown, J.C., Di Bari, M., Cesari, M., Landi, F., Vaes, B., Legrand, D., Verghese, J., and Wang, C. (2016). Short Physical Performance Battery and all-cause mortality: Systematic review and meta-analysis. BMC Med., 14.","DOI":"10.1186\/s12916-016-0763-7"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1001\/jama.2010.1923","article-title":"Gait speed and survival in older adults","volume":"305","author":"Studenski","year":"2011","journal-title":"JAMA"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1093\/ageing\/afy169","article-title":"Sarcopenia: Revised European consensus on definition and diagnosis","volume":"48","author":"Bahat","year":"2019","journal-title":"Age Ageing"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1123\/japa.2019-0133","article-title":"Reliability and Validity of the Sit-to-Stand as a Muscular Power Measure in Older Adults","volume":"28","author":"Sherwood","year":"2019","journal-title":"J. Aging Phys. Act."}],"container-title":["Diagnostics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4418\/15\/12\/1475\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:49:33Z","timestamp":1760032173000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4418\/15\/12\/1475"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,6,10]]},"references-count":30,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2025,6]]}},"alternative-id":["diagnostics15121475"],"URL":"https:\/\/doi.org\/10.3390\/diagnostics15121475","relation":{},"ISSN":["2075-4418"],"issn-type":[{"value":"2075-4418","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,6,10]]}}}