{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T06:34:05Z","timestamp":1768890845517,"version":"3.49.0"},"reference-count":37,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2025,12,4]],"date-time":"2025-12-04T00:00:00Z","timestamp":1764806400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Social Science Foundation of Fujian Province","award":["FJ2024C067"],"award-info":[{"award-number":["FJ2024C067"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Purpose: This study investigated how variations in approach speed and distance influence lower-limb muscle activation, joint co-contraction ratios (CCRs), and mechanical joint stiffness during single-leg approach run jump landings (ARJSL), to clarify adaptive neuromuscular strategies for joint stiffness regulation. Methods: Twenty-five physically active male university students performed ARJSLs under six randomized conditions combining two approach speeds (fast &gt; 4.0 m\/s; slow &lt; 4.0 m\/s) and three approach distances (3, 6, and 9 m). Surface electromyography (sEMG) from five dominant-limb muscles\u2014rectus femoris, biceps femoris, tibialis anterior, gastrocnemius, and soleus\u2014was analyzed across three movement phases: pre-activation, downward (braking), and push-off. Knee and ankle CCRs were computed, while kinematic and kinetic data were used to calculate mechanical joint stiffness via inverse dynamics. A two-way repeated-measures ANOVA evaluated the main and interaction effects of approach speed and distance. Results: Significant speed \u00d7 distance interactions were observed for tibialis anterior activation, several CCRs, and eccentric ankle stiffness (p &lt; 0.05). Pre-activation knee CCR increased with longer, faster approaches, indicating anticipatory joint pre-stiffening. During braking, greater ankle co-contraction under fast\u20139 m conditions coincided with reduced mechanical ankle stiffness, suggesting a compensatory yielding strategy under high kinetic loads. In the push-off phase, faster approaches elicited higher concentric stiffness at the hip and ankle, supporting efficient energy transfer. Rectus femoris and gastrocnemius activation scaled with both approach speed and distance. Conclusions: Athletes adapt neuromuscular co-contraction and mechanical stiffness in a coordinated, phase-dependent manner to balance protection and performance. These insights may inform targeted training strategies for enhancing jump efficiency and mitigating ACL injury risk.<\/jats:p>","DOI":"10.3390\/life15121859","type":"journal-article","created":{"date-parts":[[2025,12,4]],"date-time":"2025-12-04T13:53:30Z","timestamp":1764856410000},"page":"1859","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Adaptive Neuromuscular Co-Contraction Strategies Under Varying Approach Speeds and Distances During Single-Leg Jumping: An Exploratory Study"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5891-6279","authenticated-orcid":false,"given":"Wei-Hsun","family":"Tai","sequence":"first","affiliation":[{"name":"School of General Education, Guangzhou Institute of Science and Technology, Guangzhou 510540, China"},{"name":"Graduate Institute of Sport Coaching Science, Chinese Culture University, Taipei 11114, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4738-4561","authenticated-orcid":false,"given":"Hsien-Te","family":"Peng","sequence":"additional","affiliation":[{"name":"Graduate Institute of Sport Coaching Science, Chinese Culture University, Taipei 11114, Taiwan"},{"name":"Department of Physical Education, Chinese Culture University, Taipei 11114, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1564-8136","authenticated-orcid":false,"given":"Jian-Zhi","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Physical Education, National Taiwan University of Sport, Taichung 404401, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4652-3176","authenticated-orcid":false,"given":"Po-Ang","family":"Li","sequence":"additional","affiliation":[{"name":"School of Physical Education, Quanzhou Normal University, Quanzhou 362000, China"},{"name":"Department of Civic Education and Leadership, National Taiwan Normal University, Taipei 106308, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1515\/hukin-2017-0185","article-title":"Biomechanical Comparisons of One-Legged and Two-Legged Running Vertical Jumps","volume":"64","author":"Tai","year":"2018","journal-title":"J. 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