{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,6]],"date-time":"2026-04-06T02:14:25Z","timestamp":1775441665256,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,4,3]],"date-time":"2026-04-03T00:00:00Z","timestamp":1775174400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100007194","name":"DICYT Project 2024","doi-asserted-by":"publisher","award":["022406AT DAS"],"award-info":[{"award-number":["022406AT DAS"]}],"id":[{"id":"10.13039\/100007194","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Low back pain is common in road cyclists and has been associated with prolonged lumbar flexion during cycling. The flexion\u2013relaxation (FR) phenomenon reflects neuromuscular control of the lumbar spine, but its response to prolonged cycling under physiologically individualized conditions remains unclear. Thirty-one pain-free road cyclists completed a laboratory protocol in which exercise intensity was prescribed at 50% of the range between the first and second ventilatory thresholds (VT1 and VT2). Surface electromyography (sEMG) was recorded during trunk flexion extension tasks performed before and after a 60 min cycling trial. FR responses were characterized at both the individual and group levels using the flexion\u2013relaxation ratio (FRR), descriptive classification of altered patterns, and exploratory estimates of mean change, effect size, and 95% confidence intervals. Four cyclists (12.9%; 95% CI: 3.6\u201329.8%) exhibited altered FR responses: three showed persistent alterations already present before cycling, and one showed an exercise-associated alteration. Group-level changes were minimal (effect sizes: \u22120.20 to 0.04). These findings suggest that prolonged cycling under controlled physiological load primarily reveals heterogeneous subject-specific neuromuscular patterns rather than a uniform average response. FR assessment using sEMG may therefore be useful as a complementary tool for identifying individual neuromuscular behavior in pain-free cyclists.<\/jats:p>","DOI":"10.3390\/s26072214","type":"journal-article","created":{"date-parts":[[2026,4,6]],"date-time":"2026-04-06T01:12:33Z","timestamp":1775437953000},"page":"2214","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Surface Electromyography Reveals Subject-Specific Alterations in Lumbar Flexion\u2013Relaxation Following Prolonged Cycling in Pain-Free Road Cyclists"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3540-6345","authenticated-orcid":false,"given":"David","family":"Arriagada-Tarife\u00f1o","sequence":"first","affiliation":[{"name":"Laboratory of Applied Neuromechanics, School of Kinesiology, Faculty of Medical Sciences, Universidad de Santiago de Chile, Chacabuco N\u00b0675, Santiago 8320000, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-5221-9678","authenticated-orcid":false,"given":"Natalia","family":"Belmar","sequence":"additional","affiliation":[{"name":"Laboratory of Applied Neuromechanics, School of Kinesiology, Faculty of Medical Sciences, Universidad de Santiago de Chile, Chacabuco N\u00b0675, Santiago 8320000, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maricel","family":"Cabezas","sequence":"additional","affiliation":[{"name":"Laboratory of Applied Neuromechanics, School of Kinesiology, Faculty of Medical Sciences, Universidad de Santiago de Chile, Chacabuco N\u00b0675, Santiago 8320000, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Javiera","family":"Ceballos","sequence":"additional","affiliation":[{"name":"Laboratory of Applied Neuromechanics, School of Kinesiology, Faculty of Medical Sciences, Universidad de Santiago de Chile, Chacabuco N\u00b0675, Santiago 8320000, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-8407-4077","authenticated-orcid":false,"given":"Nicole","family":"Cede\u00f1o","sequence":"additional","affiliation":[{"name":"Laboratory of Applied Neuromechanics, School of Kinesiology, Faculty of Medical Sciences, Universidad de Santiago de Chile, Chacabuco N\u00b0675, Santiago 8320000, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3831-6513","authenticated-orcid":false,"given":"Iver","family":"Cristi-S\u00e1nchez","sequence":"additional","affiliation":[{"name":"Laboratory of Applied Neuromechanics, School of Kinesiology, Faculty of Medical Sciences, Universidad de Santiago de Chile, Chacabuco N\u00b0675, Santiago 8320000, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-2169-6359","authenticated-orcid":false,"given":"Nicol\u00e1s","family":"Casanova","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Faculty of Engineering, Universidad de Santiago de Chile, Av. Libertador Bernardo O\u2019Higgins N\u00b03363, Santiago 9170022, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-9853-9963","authenticated-orcid":false,"given":"Sebasti\u00e1n","family":"Ch\u00e1vez","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Faculty of Engineering, Universidad de Santiago de Chile, Av. Libertador Bernardo O\u2019Higgins N\u00b03363, Santiago 9170022, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6563-2955","authenticated-orcid":false,"given":"Britam","family":"G\u00f3mez","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Faculty of Engineering, Universidad de Santiago de Chile, Av. Libertador Bernardo O\u2019Higgins N\u00b03363, Santiago 9170022, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"496","DOI":"10.1111\/j.1600-0838.2011.01299.x","article-title":"Health benefits of cycling: A systematic review","volume":"21","author":"Oja","year":"2011","journal-title":"Scand. J. Med. Sci. Sport."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Leyland, L.A., Spencer, B., Beale, N., Jones, T., and Van Reekum, C.M. (2019). The effect of cycling on cognitive function and well-being in older adults. PLoS ONE, 14.","DOI":"10.1371\/journal.pone.0211779"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1016\/j.healthplace.2017.03.013","article-title":"Are buffers around home representative of physical activity spaces among adults?","volume":"45","author":"Holliday","year":"2017","journal-title":"Health Place"},{"key":"ref_4","unstructured":"Bauman, A., Rissel, C., Garrard, J., Ker, I., Speidel, R., and Fishman, E. (2008). Cycling: Getting Australia Moving: Barriers, Facilitators and Interventions to Get More Australians Physically Active Through Cycling, Cycling Promotion Fund Melbourne."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2494","DOI":"10.1177\/0363546510376816","article-title":"Overuse injuries in professional road cyclists","volume":"38","author":"Clarsen","year":"2010","journal-title":"Am. J. Sport. Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1055\/s-2007-972992","article-title":"An epidemiological analysis of overuse injuries among recreational cyclists","volume":"16","author":"Wilber","year":"1995","journal-title":"Int. J. Sport. Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"312","DOI":"10.1016\/j.math.2012.02.012","article-title":"Comparing lower lumbar kinematics in cyclists with low back pain (flexion pattern) versus asymptomatic controls\u2013field study using a wireless posture monitoring system","volume":"17","author":"Volkaerts","year":"2012","journal-title":"Man. Ther."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1249\/JSR.0b013e3182a4bab7","article-title":"Bicycling injuries","volume":"12","author":"Silberman","year":"2013","journal-title":"Curr. Sport. Med. Rep."},{"key":"ref_9","first-page":"11","article-title":"Pedal force effectiveness in cycling: A review of constraints and training effects","volume":"2","author":"Bini","year":"2013","journal-title":"J. Sci. Cycl."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"S90","DOI":"10.1016\/j.pain.2010.10.020","article-title":"Moving differently in pain: A new theory to explain the adaptation to pain","volume":"152","author":"Hodges","year":"2011","journal-title":"Pain"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"370","DOI":"10.2519\/jospt.2019.7917","article-title":"Motor control changes in low back pain: Divergence in presentations and mechanisms","volume":"49","author":"Reeves","year":"2019","journal-title":"J. Orthop. Sport. Phys. Ther."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1435","DOI":"10.1097\/01.BRS.0000067085.46840.5A","article-title":"Quantifying the lumbar flexion\u2013relaxation phenomenon: Theory, normative data, and clinical applications","volume":"28","author":"Neblett","year":"2003","journal-title":"Spine"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1016\/j.math.2004.06.002","article-title":"Spinal kinematics and trunk muscle activity in cyclists: A comparison between healthy controls and non-specific chronic low back pain subjects\u2014A pilot investigation","volume":"9","author":"Burnett","year":"2004","journal-title":"Man. Ther."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"967","DOI":"10.1007\/s00421-024-05628-7","article-title":"Alterations in magnitude and spatial distribution of erector spinae muscle activity in cyclists with a recent history of low back pain","volume":"125","author":"Sampieri","year":"2025","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1255","DOI":"10.1080\/02640414.2022.2061819","article-title":"The effect of low back pain on neuromuscular control in cyclists","volume":"40","author":"Boon","year":"2022","journal-title":"J. Sport. Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"398","DOI":"10.1136\/bjsm.33.6.398","article-title":"Effect of changing the saddle angle on the incidence of low back pain in recreational bicyclists","volume":"33","author":"Salai","year":"1999","journal-title":"Br. J. Sport. Med."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/S0268-0033(97)00065-X","article-title":"Surface electromyography in the identification of chronic low back pain patients: The development of the flexion relaxation ratio","volume":"12","author":"Watson","year":"1997","journal-title":"Clin. Biomech."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1016\/j.jmpt.2005.08.005","article-title":"The biomechanical and clinical significance of the lumbar erector spinae flexion-relaxation phenomenon: A review of literature","volume":"28","author":"Colloca","year":"2005","journal-title":"J. Manip. Physiol. Ther."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1016\/S0268-0033(03)00024-X","article-title":"Flexion\u2013relaxation response to static lumbar flexion in males and females","volume":"18","author":"Solomonow","year":"2003","journal-title":"Clin. Biomech."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1873","DOI":"10.1097\/BRS.0b013e3181aa6a55","article-title":"Creep and fatigue development in the low back in static flexion","volume":"34","author":"Shin","year":"2009","journal-title":"Spine"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1173","DOI":"10.1080\/02640414.2017.1363902","article-title":"Physiological and biomechanical responses between seated and standing positions during distance-based uphill time trials in elite cyclists","volume":"36","author":"Bouillod","year":"2018","journal-title":"J. Sport. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Brusseau, T.A., Fairclough, S.J., and Lubans, D.R. (2020). The Routledge Handbook of Youth Physical Activity, Routledge.","DOI":"10.4324\/9781003026426"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"310","DOI":"10.1123\/jab.19.4.310","article-title":"Body configuration in cycling affects muscle recruitment and movement pattern","volume":"19","author":"Savelberg","year":"2003","journal-title":"J. Appl. Biomech."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"857","DOI":"10.1016\/j.jelekin.2007.03.002","article-title":"Intra-session repeatability of lower limb muscles activation pattern during pedaling","volume":"18","author":"Dorel","year":"2008","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_25","first-page":"188","article-title":"Effects of saddle height on knee forces of recreational cyclists with and without knee pain","volume":"15","author":"Bini","year":"2014","journal-title":"Int. SportMed J."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"463","DOI":"10.2165\/11588740-000000000-00000","article-title":"Effects of bicycle saddle height on knee injury risk and cycling performance","volume":"41","author":"Bini","year":"2011","journal-title":"Sport. Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"651","DOI":"10.47197\/retos.v43i0.89363","article-title":"\u00bf Existe alguna relaci\u00f3n entre la posici\u00f3n del ciclismo y la aparici\u00f3n de dolor lumbar? Una revisi\u00f3n sistematizada. [Is there any relation between the position of cycling and the appearance of lower pain? A systematized review]","volume":"43","author":"Fuentes","year":"2022","journal-title":"Retos"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Arriagada-Tarife\u00f1o, D., Millaquipay, N.B., Salazar, M.C., Urrejola, J.C., Wolf, N.C., S\u00e1nchez, I.C., Ch\u00e1vez, S., and G\u00f3mez, B. (2024). A Novel Instrumented Test as an Indicator of Sensorimotor Disturbances in the Lumbar Spine of Road Cyclists-Preliminary Results. 2024 IEEE International Symposium on Medical Measurements and Applications (MeMeA), IEEE.","DOI":"10.1109\/MeMeA60663.2024.10596716"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"361","DOI":"10.1016\/S1050-6411(00)00027-4","article-title":"Development of recommendations for SEMG sensors and sensor placement procedures","volume":"10","author":"Hermens","year":"2000","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"198","DOI":"10.1038\/s41746-024-01191-9","article-title":"Estimation of ventilatory thresholds during exercise using respiratory wearable sensors","volume":"7","author":"Cancino","year":"2024","journal-title":"npj Digit. Med."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1007\/s13534-018-0078-z","article-title":"Electromyography-signal-based muscle fatigue assessment for knee rehabilitation monitoring systems","volume":"8","author":"Kim","year":"2018","journal-title":"Biomed. Eng. Lett."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2228","DOI":"10.1249\/MSS.0000000000000929","article-title":"Translating fatigue to human performance","volume":"48","author":"Enoka","year":"2016","journal-title":"Med. Sci. Sport. Exerc."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/7\/2214\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,6]],"date-time":"2026-04-06T01:14:06Z","timestamp":1775438046000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/7\/2214"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4,3]]},"references-count":32,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["s26072214"],"URL":"https:\/\/doi.org\/10.3390\/s26072214","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4,3]]}}}