{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T15:11:10Z","timestamp":1787584270693,"version":"build-2736575974"},"reference-count":43,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,12,18]],"date-time":"2025-12-18T00:00:00Z","timestamp":1766016000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100007414","name":"Qassim University","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100007414","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Bioeng. Biotechnol."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Bilateral asymmetry reflects strength or functional differences between dominant and non-dominant limbs, which can influence performance. Investigating asymmetry and muscle co-activation during the two-armed kettlebell swing may clarify its role in performance enhancement and injury risk. This study specifically examined co-activation and asymmetry in shoulder and trunk muscles during the exercise.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Method<\/jats:title>\n                    <jats:p>Twenty-four participants (age: 23.9 \u00b1 2.5 years; body mass: 82.8 \u00b1 8.0\u00a0kg; height: 177.8 \u00b1 6.5\u00a0cm) were included in the study. Surface electromyography signals were recorded using a wireless EMG system and data were collected bilaterally from twelve muscles (six muscles per side: anterior deltoid, posterior deltoid, erector spinae longissimus, erector spinae iliocostalis, external oblique, and rectus abdominis). Each participant completed two trials of the two-armed kettlebell swing, with at least five repetitions.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The results showed that the shoulder co-activation index significantly increased on both sides during the float, drop, and deceleration phases (Right side: F = 35.12; p &amp;lt; 0.001; Left side: F = 69.80; p &amp;lt; 0.001). Additionally, co-activation between the erector spinae and rectus abdominis, as well as between the erector spinae and external oblique muscles, was highest during the float and drop phases (Right side: F = 165.1; p &amp;lt; 0.001; Left side: F = 100.08; p &amp;lt; 0.001). The findings revealed some asymmetry in muscle co-activation, particularly during the float phase (22.39%). However, overall asymmetrical levels remained low during the more mechanically demanding phases (propulsion, drop, and deceleration).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>The study shows clear phase-dependent muscle activation patterns, with anterior deltoid and spinal extensors leading during propulsion, and greater posterior engagement and co-activation stabilizing the float, drop, and deceleration phases. A small asymmetry appeared mainly in the float phase, while the overall asymmetry index stayed low during the more demanding phases.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fbioe.2025.1655248","type":"journal-article","created":{"date-parts":[[2025,12,18]],"date-time":"2025-12-18T06:45:12Z","timestamp":1766040312000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Asymmetry of muscle co-activation during the two-armed kettlebell swing: insights into neuromuscular stability"],"prefix":"10.3389","volume":"13","author":[{"given":"Khaled","family":"Abuwarda","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abdulazeem","family":"Alotaibi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abdel-Rahman","family":"Akl","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,12,18]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"1497826","DOI":"10.3389\/fspor.2024.1497826","article-title":"Assessment of trunk and shoulder muscle asymmetries during two-armed kettlebell swings: implications for training optimization and injury prevention","volume":"6","author":"Abuwarda","year":"2024","journal-title":"Front. 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