{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T21:38:31Z","timestamp":1781732311345,"version":"3.54.5"},"reference-count":33,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,9,11]],"date-time":"2025-09-11T00:00:00Z","timestamp":1757548800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JFMK"],"abstract":"<jats:p>Background: This study compared the acute effect of performing quarter (QS) and parallel (PS) squat with variable resistance (VR) on countermovement jump (CMJ) performance. Methods: Fifteen resistance trained athletes (age: 27.0 \u00b1 3.7 years, bodyweight: 68.4 \u00b1 7.7 kg, height: 169.7 \u00b1 6.9 cm) performed either the QS or PS to induce post-activation performance enhancement on two separate occasions. During each session, participants performed three repetitions of baseline CMJ prior to performing three repetitions of either QS or PS at their three-repetition maximum load. Participants then performed the post-test CMJ after a five-minute recovery period. Results: Both conditions resulted in increased jump height (QS: p &lt; 0.001, g = 0.19, PS: p &lt; 0.001, g = 0.35). Countermovement depth and time to take-off were significantly decreased in QS (p &lt; 0.001, g = 0.63 and p = 0.005, g = 0.30, respectively) but significantly increased in PS (p = 0.027, g = 0.39 and p &lt; 0.001, g = 0.36, respectively). Mean propulsion force was significantly increased in QS (p &lt; 0.001, g = 0.23) but significantly decreased in PS (p = 0.083, g = 0.13). PS resulted in greater change in jump height (p &lt; 0.001, g = 1.34) and time to take-off (p = 0.005, g = 1.25), while QS resulted in greater change in countermovement depth (p &lt; 0.001, g = 2.33) and mean propulsion force (p &lt; 0.001, g = 1.67). Conclusions: The results showed that performing PS and QS with VR was effective in enhancing CMJ height. However, the two conditions resulted in participants adopting different jump strategies when performing the post-test CMJ.<\/jats:p>","DOI":"10.3390\/jfmk10030347","type":"journal-article","created":{"date-parts":[[2025,9,11]],"date-time":"2025-09-11T14:23:50Z","timestamp":1757600630000},"page":"347","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Post-Activation Performance Enhancement of Lower Limb with Variable Resistance Back Squat at Different Depths"],"prefix":"10.3390","volume":"10","author":[{"given":"Choon Yeow","family":"Ng","sequence":"first","affiliation":[{"name":"Singapore Weightlifting Federation, Singapore 469643, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8908-3791","authenticated-orcid":false,"given":"Danny","family":"Lum","sequence":"additional","affiliation":[{"name":"High Performance Sport Institute, Singapore 397630, Singapore"},{"name":"Sport Performance, and Nutrition Research Group, School of Allied Health, Human Services, & Sport, La Trobe University, Melbourne, VIC 3086, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Blazevich, A.J., and Babault, N. 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