{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T10:13:12Z","timestamp":1773396792644,"version":"3.50.1"},"reference-count":33,"publisher":"American Physiological Society","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Applied Physiology"],"published-print":{"date-parts":[[2009,7]]},"abstract":"<jats:p> Single motor unit electromyographic (EMG) activity of the knee extensors was investigated at different knee angles with subjects ( n = 10) exerting the same absolute submaximal isometric torque at each angle. Measurements were made over a 20\u00b0 range around the optimum angle for torque production (AngleTmax) and, where feasible, over a wider range (50\u00b0). Forty-six vastus lateralis (VL) motor units were recorded at 20.7 \u00b1 17.9 %maximum voluntary contraction (%MVC) together with the rectified surface EMG (rsEMG) of the superficial VL muscle. Due to the lower maximal torque capacity at positions more flexed and extended than AngleTmax, single motor unit recruitment thresholds were expected to decrease and discharge rates were expected to increase at angles above and below AngleTmax. Unexpectedly, the recruitment threshold was higher ( P &lt; 0.05) at knee angles 10\u00b0 more extended (43.7 \u00b1 22.2 N\u00b7m) and not different ( P &gt; 0.05) at knee angles 10\u00b0 more flexed (35.2 \u00b1 17.9 N\u00b7m) compared with recruitment threshold at AngleTmax (41.8 \u00b1 21.4 N\u00b7m). Also, unexpectedly the discharge rates were similar ( P &gt; 0.05) at the three angles: 11.6 \u00b1 2.2, 11.6 \u00b1 2.1, and 12.3 \u00b1 2.1 Hz. Similar angle independent discharge rates were also found for 12 units ( n = 5; 7.4 \u00b1 5.4 %MVC) studied over the wider (50\u00b0) range, while recruitment threshold only decreased at more flexed angles. In conclusion, the similar recruitment threshold and discharge behavior of VL motor units during submaximal isometric torque production suggests that net motor unit activation did not change very much along the ascending limb of the knee-angle torque relationship. Several factors such as length-dependent twitch potentiation, which may contribute to this unexpected aspect of motor control, are discussed. <\/jats:p>","DOI":"10.1152\/japplphysiol.90322.2008","type":"journal-article","created":{"date-parts":[[2009,5,21]],"date-time":"2009-05-21T21:26:04Z","timestamp":1242941164000},"page":"80-89","source":"Crossref","is-referenced-by-count":22,"title":["Vastus lateralis single motor unit EMG at the same absolute torque production at different knee angles"],"prefix":"10.1152","volume":"107","author":[{"given":"T. M.","family":"Altenburg","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"A.","family":"de Haan","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"P. W. 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