{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T21:04:12Z","timestamp":1774559052775,"version":"3.50.1"},"reference-count":55,"publisher":"Public Library of Science (PLoS)","issue":"3","license":[{"start":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T00:00:00Z","timestamp":1774483200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004358","name":"SAMSUNG electronics","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100004358","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"crossref","award":["2020R1A2B5B01002395"],"award-info":[{"award-number":["2020R1A2B5B01002395"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Korea Institute for Advancement of Technology (KIAT) through a grant funded by the Korea government","award":["P0020535"],"award-info":[{"award-number":["P0020535"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>This study introduces Bot Fit, an innovative hip-joint exoskeleton designed for the objective assessment of lower limb muscular strength and exercise performance. A total of 25 participants underwent baseline strength assessments using conventional fitness equipment before performing resistance exercises under two controlled conditions: a 10-second test without speed restrictions and a 30-second test at a constant speed. Bot Fit recorded motor signals and performance metrics, capturing key indicators such as repetitions and movement patterns. To analyze the relationship between muscle parameters and exercise performance, we employed correlation analysis, hierarchical cluster analysis (HCA), and regression analysis. The results demonstrated strong associations between lower limb strength and key exercises, including squats, knee-ups, and reverse lunges, particularly in short-duration and constant-speed conditions. HCA successfully clustered participants based on three exercise-related metrics with an accuracy of 0.89, while the regression model achieved a correlation coefficient of 0.86, indicating high statistical power. These findings suggest that Bot Fit provides a reliable, data-driven method for muscular strength assessment, offering valuable insights for optimizing exercise programs, preventing injuries, and enhancing physical performance. The integration of wearable robotic technology into health and fitness monitoring enables personalized exercise interventions and supports evidence-based decision-making in sports science, rehabilitation, and performance enhancement.<\/jats:p>","DOI":"10.1371\/journal.pone.0339187","type":"journal-article","created":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T20:03:47Z","timestamp":1774555427000},"page":"e0339187","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Bot fit: A novel approach to assessing lower limb muscular strength"],"prefix":"10.1371","volume":"21","author":[{"given":"Byungmun","family":"Kang","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0863-1694","authenticated-orcid":true,"given":"DaeEun","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Changmin","family":"Lee","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0668-3602","authenticated-orcid":true,"given":"Dongwoo","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hwang-Jae","family":"Lee","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dokwan","family":"Lee","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"YoonMyung","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyung-Gyu","family":"Jeon","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-5336-6510","authenticated-orcid":true,"given":"Kyunghwan","family":"Jung","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2026,3,26]]},"reference":[{"issue":"7661","key":"pone.0339187.ref001","article-title":"Association between muscular strength and mortality in men: Prospective cohort study","volume":"337","author":"JR Ruiz","year":"2008","journal-title":"BMJ."},{"issue":"3","key":"pone.0339187.ref002","article-title":"Progressive resistance strength training for improving physical function in older adults","volume":"2009","author":"C-J Liu","year":"2009","journal-title":"Cochrane Database Syst Rev."},{"issue":"4","key":"pone.0339187.ref003","doi-asserted-by":"crossref","first-page":"412","DOI":"10.1093\/ageing\/afq034","article-title":"Sarcopenia: European consensus on definition and diagnosis: Report of the European Working Group on Sarcopenia in older people","volume":"39","author":"AJ Cruz-Jentoft","year":"2010","journal-title":"Age Ageing."},{"issue":"10","key":"pone.0339187.ref004","doi-asserted-by":"crossref","first-page":"1419","DOI":"10.1007\/s40279-016-0486-0","article-title":"The importance of muscular strength in athletic performance","volume":"46","author":"TJ Suchomel","year":"2016","journal-title":"Sports Med."},{"issue":"6","key":"pone.0339187.ref005","first-page":"367","article-title":"Muscle rehabilitation: Its effect on muscular and functional performance of patients with knee osteoarthritis","volume":"72","author":"NM Fisher","year":"1991","journal-title":"Arch Phys Med Rehabil."},{"key":"pone.0339187.ref006","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1016\/j.measurement.2014.10.049","article-title":"Power as a parameter in the functional assessment of knee flexions and knee extensions on weight stack machines","volume":"61","author":"E Zemkov\u00e1","year":"2015","journal-title":"Measurement."},{"key":"pone.0339187.ref007","doi-asserted-by":"crossref","unstructured":"Siff MC. Biomechanical foundations of strength and power training. biomechanics in sport. Wiley. 2000. 103\u201339. https:\/\/doi.org\/10.1002\/9780470693797.ch6","DOI":"10.1002\/9780470693797.ch6"},{"issue":"1","key":"pone.0339187.ref008","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1080\/02640410802428089","article-title":"One-repetition maximum strength test represents a valid means to assess leg strength in vivo in humans","volume":"27","author":"LB Verdijk","year":"2009","journal-title":"J Sports Sci."},{"issue":"7","key":"pone.0339187.ref009","doi-asserted-by":"crossref","first-page":"1810","DOI":"10.1519\/JSC.0b013e3181ddb03d","article-title":"Assessing muscular strength in youth: Usefulness of standing long jump as a general index of muscular fitness","volume":"24","author":"J Castro-Pi\u00f1ero","year":"2010","journal-title":"J Strength Cond Res."},{"issue":"1","key":"pone.0339187.ref010","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1016\/j.peh.2016.01.001","article-title":"Doping prevention through anti-doping education and practical strength training: The Hercules program","volume":"5","author":"D Sagoe","year":"2016","journal-title":"Perform Enhance Health."},{"issue":"3","key":"pone.0339187.ref011","doi-asserted-by":"crossref","first-page":"100254","DOI":"10.1016\/j.peh.2023.100254","article-title":"A qualitative study of how and why gym-based resistance training may benefit women\u2019s mental health and wellbeing","volume":"11","author":"FC Hall","year":"2023","journal-title":"Perform Enhance Health."},{"issue":"2","key":"pone.0339187.ref012","first-page":"433","article-title":"Short-term effects on lower-body functional power development: Weightlifting vs. vertical jump training programs","volume":"19","author":"V Tricoli","year":"2005","journal-title":"J Strength Cond Res."},{"issue":"2","key":"pone.0339187.ref013","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0056137","article-title":"A simple exoskeleton that assists plantarflexion can reduce the metabolic cost of human walking","volume":"8","author":"P Malcolm","year":"2013","journal-title":"PLoS One."},{"key":"pone.0339187.ref014","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/TSMC.2018.2836913","article-title":"Robust ground reaction force estimation and control of lower-limb prostheses: Theory and simulation","author":"V Azimi","year":"2018","journal-title":"IEEE Trans Syst Man Cybern, Syst."},{"issue":"1","key":"pone.0339187.ref015","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1186\/s12984-020-00777-0","article-title":"Wearable hip-assist robot modulates cortical activation during gait in stroke patients: A functional near-infrared spectroscopy study","volume":"17","author":"S-H Lee","year":"2020","journal-title":"J Neuroeng Rehabil."},{"issue":"9","key":"pone.0339187.ref016","first-page":"1549","article-title":"A wearable hip assist robot can improve gait function and cardiopulmonary metabolic efficiency in elderly adults","volume":"25","author":"H-J Lee","year":"2017","journal-title":"IEEE Trans Neural Syst Rehabil Eng."},{"issue":"1","key":"pone.0339187.ref017","doi-asserted-by":"crossref","first-page":"7269","DOI":"10.1038\/s41598-023-32335-8","article-title":"Exercise with a wearable hip-assist robot improved physical function and walking efficiency in older adults","volume":"13","author":"S-H Lee","year":"2023","journal-title":"Sci Rep."},{"issue":"5","key":"pone.0339187.ref018","doi-asserted-by":"crossref","first-page":"643","DOI":"10.3390\/healthcare11050643","article-title":"Functional improvement and satisfaction with a wearable hip exoskeleton in community-living adults","volume":"11","author":"J Kim","year":"2023","journal-title":"Healthcare (Basel)."},{"issue":"5","key":"pone.0339187.ref019","doi-asserted-by":"crossref","first-page":"106675","DOI":"10.1016\/j.isci.2023.106675","article-title":"Brain-computer interface enhanced by virtual reality training for controlling a lower limb exoskeleton","volume":"26","author":"L Ferrero","year":"2023","journal-title":"iScience."},{"issue":"8","key":"pone.0339187.ref020","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0231996","article-title":"Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons","volume":"15","author":"RW Nuckols","year":"2020","journal-title":"PLoS ONE."},{"issue":"9","key":"pone.0339187.ref021","article-title":"Lower limb sagittal kinematic and kinetic modeling of very slow walking for gait trajectory scaling","volume":"13","author":"AJJ Smith","year":"2018","journal-title":"PLoS One."},{"key":"pone.0339187.ref022","doi-asserted-by":"crossref","DOI":"10.1016\/j.pmrj.2018.06.005","article-title":"Exoskeleton and end-effector robots for upper and lower limbs rehabilitation: Narrat Rev","volume":"10","author":"F Molteni","year":"2018","journal-title":"PM R."},{"issue":"2","key":"pone.0339187.ref023","doi-asserted-by":"crossref","first-page":"1502","DOI":"10.1080\/10447318.2024.2342101","article-title":"On the remarkable advancement of assistive robotics in human-robot interaction-based health-care applications: An exploratory overview of the literature","volume":"41","author":"F Gongor","year":"2024","journal-title":"Int J Human\u2013Comput Interact."},{"issue":"1","key":"pone.0339187.ref024","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1186\/s12984-021-00964-7","article-title":"The effect of pelvic movements of a gait training system for stroke patients: A single blind, randomized, parallel study","volume":"18","author":"C Son","year":"2021","journal-title":"J Neuroeng Rehabil."},{"issue":"8","key":"pone.0339187.ref025","article-title":"A real-time stable-control gait switching strategy for lower-limb rehabilitation exoskeleton","volume":"15","author":"Z Guo","year":"2020","journal-title":"PLoS One."},{"key":"pone.0339187.ref026","doi-asserted-by":"crossref","first-page":"1004","DOI":"10.1249\/01.mss.0000989172.02999.22","article-title":"Exoskeleton-based upper extremity function assessment in virtual reality for stroke patients","volume":"55","author":"H Li","year":"2023","journal-title":"Med Sci Sports Exerc."},{"issue":"1","key":"pone.0339187.ref027","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1186\/s12984-017-0333-z","article-title":"Gait performance and foot pressure distribution during wearable robot-assisted gait in elderly adults","volume":"14","author":"S-H Lee","year":"2017","journal-title":"J Neuroeng Rehabil."},{"issue":"1","key":"pone.0339187.ref028","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1186\/s12877-018-0921-1","article-title":"A wearable hip-assist robot reduces the cardiopulmonary metabolic energy expenditure during stair ascent in elderly adults: A pilot cross-sectional study","volume":"18","author":"D-S Kim","year":"2018","journal-title":"BMC Geriatr."},{"issue":"3","key":"pone.0339187.ref029","doi-asserted-by":"crossref","first-page":"285","DOI":"10.1136\/bjsm.2002.002071","article-title":"Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players","volume":"38","author":"U Wisl\u00f8ff","year":"2004","journal-title":"Br J Sports Med."},{"key":"pone.0339187.ref030","unstructured":"Krisnan L, Hoo L, Lim B, Teo E. The effect of 4-week leg extension training on the strength of quadricaps muscles. 2014."},{"issue":"16","key":"pone.0339187.ref031","doi-asserted-by":"crossref","first-page":"8733","DOI":"10.3390\/ijerph18168733","article-title":"Biceps Femoris activation during hamstring strength exercises: A systematic review","volume":"18","author":"L Llurda-Almuzara","year":"2021","journal-title":"Int J Environ Res Public Health."},{"issue":"17","key":"pone.0339187.ref032","doi-asserted-by":"crossref","first-page":"4999","DOI":"10.3390\/s20174999","article-title":"Assessing the validity and reliability of a low-cost microcontroller-based load cell amplifier for measuring lower limb and upper limb muscular force","volume":"20","author":"J Gaudet","year":"2020","journal-title":"Sensors (Basel)."},{"issue":"2","key":"pone.0339187.ref033","doi-asserted-by":"crossref","first-page":"97","DOI":"10.2519\/jospt.2017.6651","article-title":"Diagnostic accuracy of handheld dynamometry and 1-repetition-maximum tests for identifying meaningful quadriceps strength asymmetries","volume":"47","author":"JA Sinacore","year":"2017","journal-title":"J Orthop Sports Phys Ther."},{"issue":"8","key":"pone.0339187.ref034","doi-asserted-by":"crossref","first-page":"2119","DOI":"10.1519\/JSC.0b013e318278f0ac","article-title":"Abdominal and hip flexor muscle activity during 2 minutes of sit-ups and curl-ups","volume":"27","author":"AM Burden","year":"2013","journal-title":"J Strength Cond Res."},{"issue":"3","key":"pone.0339187.ref035","doi-asserted-by":"crossref","first-page":"667","DOI":"10.1519\/JSC.0000000000001323","article-title":"Muscle activation patterns during different squat techniques","volume":"31","author":"LV Slater","year":"2017","journal-title":"J Strength Cond Res."},{"issue":"4","key":"pone.0339187.ref036","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0230841","article-title":"Electromyographic activity in the gluteus medius, gluteus maximus, biceps femoris, vastus lateralis, vastus medialis and rectus femoris during the monopodal squat, forward lunge and lateral step-up exercises","volume":"15","author":"JM Muyor","year":"2020","journal-title":"PLoS One."},{"issue":"7","key":"pone.0339187.ref037","doi-asserted-by":"crossref","first-page":"444","DOI":"10.1016\/S0161-4754(99)70032-1","article-title":"The importance of normalization in the interpretation of surface electromyography: A proof of principle","volume":"22","author":"GJ Lehman","year":"1999","journal-title":"J Manipulat Physiol Therapeut."},{"issue":"1","key":"pone.0339187.ref038","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1186\/s13052-023-01504-w","article-title":"Associations between basic motor competencies and physical fitness in Spanish pre-schoolers: A cross-sectional study","volume":"49","author":"G Legarra-Gorgo\u00f1on","year":"2023","journal-title":"Italian J Pediatr."},{"issue":"1","key":"pone.0339187.ref039","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1519\/JSC.0b013e31818eff0b","article-title":"Body weight-normalized knee extension strength explains sit-to-stand independence: A validation study","volume":"23","author":"RW Bohannon","year":"2009","journal-title":"J Strength Cond Res."},{"issue":"5","key":"pone.0339187.ref040","doi-asserted-by":"crossref","first-page":"1763","DOI":"10.1213\/ANE.0000000000002864","article-title":"Correlation coefficients: Appropriate use and interpretation","volume":"126","author":"P Schober","year":"2018","journal-title":"Anesth Analg."},{"issue":"1","key":"pone.0339187.ref041","doi-asserted-by":"crossref","first-page":"5","DOI":"10.2478\/cjece-2020-0002","article-title":"R Libraries {dendextend} and {magrittr} and clustering package scipy.cluster of python for modelling diagrams of dendrogram trees","volume":"13","author":"P Lemenkova","year":"2020","journal-title":"Carpathian J Electr Comput Eng."},{"key":"pone.0339187.ref042","doi-asserted-by":"crossref","first-page":"1431015","DOI":"10.3389\/fbioe.2024.1431015","article-title":"Multivariable analysis for predicting lower limb muscular strength with a hip-joint exoskeleton","volume":"12","author":"B Kang","year":"2024","journal-title":"Front Bioeng Biotechnol."},{"issue":"1","key":"pone.0339187.ref043","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1016\/j.peh.2016.06.002","article-title":"Factors affecting airport apron workers\u2019 preference on cooling vests","volume":"5","author":"APC Chan","year":"2016","journal-title":"Perform Enhance Health."},{"key":"pone.0339187.ref044","doi-asserted-by":"crossref","first-page":"111","DOI":"10.3389\/fpsyg.2012.00111","article-title":"A practical guide to calculating Cohen\u2019s f(2), a measure of local effect size, from PROC MIXED","volume":"3","author":"AS Selya","year":"2012","journal-title":"Front Psychol."},{"key":"pone.0339187.ref045","volume-title":"Statistical power analysis: A simple and general model for traditional and modern hypothesis tests","author":"B Myors","year":"2010"},{"issue":"4","key":"pone.0339187.ref046","doi-asserted-by":"crossref","first-page":"51","DOI":"10.3390\/jfmk3040051","article-title":"Short-term effects of suspension training on strength and power performances","volume":"3","author":"GF Giancotti","year":"2018","journal-title":"J Funct Morphol Kinesiol."},{"issue":"1","key":"pone.0339187.ref047","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1016\/j.apmr.2006.10.002","article-title":"Measuring muscle strength for people with chronic obstructive pulmonary disease: Retest reliability of hand-held dynamometry","volume":"88","author":"SD O\u2019Shea","year":"2007","journal-title":"Arch Phys Med Rehabil."},{"issue":"3","key":"pone.0339187.ref048","first-page":"567","article-title":"Predicting a 10 repetition maximum for the free weight parallel squat using the 45\u2218 angled leg press","volume":"18","author":"JM Willardson","year":"2004","journal-title":"J Strength Cond Res."},{"issue":"2","key":"pone.0339187.ref049","first-page":"154","article-title":"Effects of regular and slow speed resistance training on muscle strength","volume":"41","author":"WL Westcott","year":"2001","journal-title":"J Sports Med Phys Fitness."},{"issue":"3","key":"pone.0339187.ref050","first-page":"44","article-title":"Maximum strength and strength training\u2014A relationship to endurance?","volume":"28","author":"MH Stone","year":"2006","journal-title":"J Strength Cond."},{"issue":"8","key":"pone.0339187.ref051","doi-asserted-by":"crossref","first-page":"2078","DOI":"10.1519\/JSC.0b013e31823b06ff","article-title":"Associations of maximal strength and muscular endurance test scores with cardiorespiratory fitness and body composition","volume":"26","author":"JP Vaara","year":"2012","journal-title":"J Strength Cond Res."},{"issue":"1","key":"pone.0339187.ref052","doi-asserted-by":"crossref","first-page":"724","DOI":"10.1186\/s12877-023-04423-x","article-title":"Effect of 4-weeks exercise program using wearable hip-assist robot (EX1) in older adults: One group pre- and post-test","volume":"23","author":"J-H Shin","year":"2023","journal-title":"BMC Geriatr."},{"issue":"3","key":"pone.0339187.ref053","doi-asserted-by":"crossref","first-page":"147","DOI":"10.2165\/00007256-199724030-00001","article-title":"Influence of strength training on sprint running performance. Current findings and implications for training","volume":"24","author":"C Delecluse","year":"1997","journal-title":"Sports Med."},{"key":"pone.0339187.ref054","doi-asserted-by":"crossref","first-page":"257","DOI":"10.2147\/OAJSM.S68932","article-title":"Effects of 16-week high-intensity interval training using upper and lower body ergometers on aerobic fitness and morphological changes in healthy men: A preliminary study","volume":"5","author":"Y Osawa","year":"2014","journal-title":"Open Access J Sports Med."},{"key":"pone.0339187.ref055","volume-title":"Senior fitness test manual","author":"R Rikli","year":"2001"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0339187","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T20:03:58Z","timestamp":1774555438000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0339187"}},"subtitle":[],"editor":[{"given":"Hasan","family":"Sozen","sequence":"first","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[2026,3,26]]},"references-count":55,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,3,26]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0339187","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,26]]}}}