{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T12:10:43Z","timestamp":1790079043345,"version":"4.0.1"},"reference-count":38,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T00:00:00Z","timestamp":1789689600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Muscles"],"abstract":"<jats:p>Sprinters and jumpers differ in their force\u2013velocity demands, so this exploratory study compared their acute countermovement jump (CMJ) response to isometric conditioning. Methods: Twenty-two competitive track and field athletes (10 sprinters, 12 jumpers; 19.1 \u00b1 3.3 y) were alternately allocated from a randomised list to a 3 \u00d7 5 s isometric knee-extension or isometric half-squat (n = 11 each). Discipline was not manipulated, and no control condition was included. CMJ height was assessed from flight time by frame-by-frame video analysis, with take-off and landing timestamps read to the nearest 0.01 s. The best of three jumps was the primary trial summary. Percentage change (\u0394CMJ) was the primary outcome. Results: Sprinters increased (+2.40 \u00b1 4.46%) whereas jumpers decreased (\u22122.02 \u00b1 6.44%). Discipline and protocol were analysed jointly in one additive model. The protocol contrast was small and imprecise (\u22120.25 percentage points [ISO-SQ relative to IKE], 95% CI \u22125.50 to 5.00; p = 0.921). The unadjusted discipline difference was non-significant (4.42 percentage points, 95% CI \u22120.46 to 9.30; p = 0.074) and the parallel Mann\u2013Whitney U test was borderline and implementation-dependent (p = 0.043\u20130.050). After age adjustment it attenuated to +2.51 percentage points (95% CI \u22122.65 to 7.66; p = 0.320), whereas age remained associated with \u0394CMJ (\u22120.86% per year; p = 0.042). Post hoc averaged trial summaries gave larger contrasts. Conclusions: The primary comparison was inconclusive and materially attenuated by age adjustment but directionally consistent across trial summaries and protocols. The observed discipline-dependent pattern is hypothesis-generating and requires confirmation in adequately powered, controlled trials.<\/jats:p>","DOI":"10.3390\/muscles5030067","type":"journal-article","created":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T10:21:48Z","timestamp":1790072508000},"page":"67","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Do Sprinters and Jumpers Differ in the Acute Countermovement-Jump Response to Isometric Conditioning Protocols? An Exploratory Study"],"prefix":"10.3390","volume":"5","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-2063-123X","authenticated-orcid":false,"given":"Atila","family":"Salaj","sequence":"first","affiliation":[{"name":"Faculty of Kinesiology Osijek, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3663-4008","authenticated-orcid":false,"given":"Hrvoje","family":"Ajman","sequence":"additional","affiliation":[{"name":"Faculty of Kinesiology Osijek, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-0066-8040","authenticated-orcid":false,"given":"Frane","family":"\u017duvela","sequence":"additional","affiliation":[{"name":"Faculty of Kinesiology, University of Split, 21000 Split, Croatia"},{"name":"Research Group \u201cAthletics and Kinesiological Development of Children and Youth\u201d, Faculty of Kinesiology, University of Split, 21000 Split, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9158-2779","authenticated-orcid":false,"given":"Petar","family":"\u0160u\u0161njara","sequence":"additional","affiliation":[{"name":"Faculty of Kinesiology Osijek, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Blazevich, A.J., and Babault, N. 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