{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T11:46:57Z","timestamp":1790164017263,"version":"4.1.0"},"reference-count":36,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,3,8]],"date-time":"2026-03-08T00:00:00Z","timestamp":1772928000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>This investigation examined whether mirror visual feedback modulates crossover fatigue magnitude during unilateral handgrip exertion and whether efficacy demonstrates age-dependent and muscle-group-specific characteristics. Thirty-three participants stratified by developmental stage (adults: n = 17, 24.64 \u00b1 5.38 years; children: n = 16, 11.87 \u00b1 0.79 years) completed a randomized controlled crossover protocol incorporating three visual feedback conditions: mirror reflection of the exercised limb, occluded vision (no-mirror), and passive rest control. Participants performed unilateral dominant handgrip fatigue induction (20 \u00d7 6 s maximal voluntary isometric contractions) while bilateral force production was quantified pre-intervention and post-intervention across handgrip, elbow flexion, and elbow extension domains. Linear mixed-effects models with participant-specific random intercepts and slopes quantified Condition \u00d7 Time \u00d7 Limb interactions. In the non-exercised contralateral limb, linear mixed-effects models demonstrated that under the mirror condition, non-dominant handgrip force was maintained at rest-equivalent levels relative to control (+0.02 kg, 95% CI [\u22121.15, +1.17], p = 0.987, dz =+ 0.003), whereas vision occlusion induced significant crossover fatigue (\u22123.37 kg [\u22124.40, \u22122.35], p &lt; 0.001, dz =\u2212 1.16). All contrasts represent within-subject difference-of-differences in non-dominant limb change score (Post \u2212 Pre) extracted from the full factorial LMM via emmeans within the Limb = Non-dominant stratum pooled across age groups. The mirror versus no-mirror comparison yielded +3.38 kg [+2.43, +4.34], p &lt; 0.001, dz =+ 1.26. Age-stratified analyses confirmed comparable effect magnitudes (adults: dz =+ 1.40; children: dz =+ 1.33). Muscle-group specificity emerged for handgrip but not elbow flexion (p = 0.068) or extension (p = 0.156). Age Group \u00d7 Condition \u00d7 Time \u00d7 Limb interactions were non-significant (all p &gt; 0.16), providing no evidence of age moderation within the tested developmental range. Mirror visual feedback constitutes an effective countermeasure against crossover fatigue in distal upper limb musculature. The magnitude of mirror-induced attenuation did not differ between children (aged 10\u201313 years) and adults within our sample, with no statistically detectable age moderation within the tested developmental range; formal equivalence testing was not conducted. Effects demonstrated anatomical selectivity, favoring hand musculature over proximal elbow musculature.<\/jats:p>","DOI":"10.3390\/life16030435","type":"journal-article","created":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T11:06:52Z","timestamp":1773054412000},"page":"435","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Mirror Visual Feedback Selectively Attenuates Crossover Fatigue in Distal Upper Limb Musculature: A Randomized Controlled Crossover Investigation Comparing Children and Adults"],"prefix":"10.3390","volume":"16","author":[{"given":"Aymen Ben","family":"Othman","sequence":"first","affiliation":[{"name":"High Institute of Sport and Physical Education of Kef, University of Jendouba, Kef 7100, Tunisia"},{"name":"Tunisian Research Laboratory \u201cSport Performance Optimisation\u201d National Center of Medicine and Science in Sports, Tunis 1004, Tunisia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6221-546X","authenticated-orcid":false,"given":"Wissem","family":"Dhahbi","sequence":"additional","affiliation":[{"name":"Research Unit \u201cSport Sciences, Health and Movement\u201d (UR22JS01) High Institute of Sport and Physical Education of Kef, University of Jendouba, Kef 7100, Tunisia"},{"name":"Training Department, Police College, Qatar Police Academy, Doha 7157, Qatar"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manel","family":"Bessifi","sequence":"additional","affiliation":[{"name":"Research Unit \u201cSport Sciences, Health and Movement\u201d (UR22JS01) High Institute of Sport and Physical Education of Kef, University of Jendouba, Kef 7100, Tunisia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8488-1698","authenticated-orcid":false,"given":"Vlad Adrian","family":"Geant\u0103","sequence":"additional","affiliation":[{"name":"Department of Physical Education and Sport, Faculty of Physical Education and Sport, Aurel Vlaicu University of Arad, 310025 Arad, Romania"},{"name":"Doctoral School of Sport Science and Physical Education, Pitesti University Center, National University of Science and Technology Politehnica Bucharest, 110253 Pite\u0219ti, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vasile Emil","family":"Ursu","sequence":"additional","affiliation":[{"name":"Department of Physical Education and Sport, Faculty of Law and Social Sciences, University \u201c1 Decembrie 1918\u201d of Alba Iulia, 510009 Alba Iulia, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9406-6056","authenticated-orcid":false,"given":"David G.","family":"Behm","sequence":"additional","affiliation":[{"name":"School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John\u2019s, NL A1C 5S7, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karim","family":"Chamari","sequence":"additional","affiliation":[{"name":"Research & Education Department, Naufar Center, Doha 3263, Qatar"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anis","family":"Chaouachi","sequence":"additional","affiliation":[{"name":"Tunisian Research Laboratory \u201cSport Performance Optimisation\u201d National Center of Medicine and Science in Sports, Tunis 1004, Tunisia"},{"name":"High Institute of Sport and Physical Education, Ksar-Said, Manouba University, Tunis 2010, Tunisia"},{"name":"Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland 0632, New Zealand"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2031","DOI":"10.1007\/s00421-015-3249-y","article-title":"Non-local muscle fatigue: Effects and possible mechanisms","volume":"115","author":"Halperin","year":"2015","journal-title":"Eur. 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