{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,20]],"date-time":"2026-10-20T01:53:09Z","timestamp":1792461189528,"version":"4.5.0"},"reference-count":61,"publisher":"American Physiological Society","issue":"11","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Regulatory, Integrative and Comparative Physiology"],"published-print":{"date-parts":[[2016,6,1]]},"abstract":"<jats:p> The complexity of knee extensor torque time series decreases during fatiguing isometric muscle contractions. We hypothesized that because of peripheral fatigue, this loss of torque complexity would occur exclusively during contractions above the critical torque (CT). Nine healthy participants performed isometric knee extension exercise (6 s of contraction, 4 s of rest) on six occasions for 30 min or to task failure, whichever occurred sooner. Four trials were performed above CT (trials S1\u2013S4, S1 being the lowest intensity), and two were performed below CT (at 50% and 90% of CT). Global, central, and peripheral fatigue were quantified using maximal voluntary contractions (MVCs) with femoral nerve stimulation. The complexity of torque output was determined using approximate entropy (ApEn) and the detrended fluctuation analysis-\u03b1 scaling exponent (DFA-\u03b1). The MVC torque was reduced in trials below CT [by 19 \u00b1 4% (means \u00b1 SE) in 90%CT], but complexity did not decrease [ApEn for 90%CT: from 0.82 \u00b1 0.03 to 0.75 \u00b1 0.06, 95% paired-samples confidence intervals (CIs), 95% CI = \u22120.23, 0.10; DFA-\u03b1 from 1.36 \u00b1 0.01 to 1.32 \u00b1 0.03, 95% CI \u22120.12, 0.04]. Above CT, substantial reductions in MVC torque occurred (of 49 \u00b1 8% in S1), and torque complexity was reduced (ApEn for S1: from 0.67 \u00b1 0.06 to 0.14 \u00b1 0.01, 95% CI = \u22120.72, \u22120.33; DFA-\u03b1 from 1.38 \u00b1 0.03 to 1.58 \u00b1 0.01, 95% CI 0.12, 0.29). Thus, in these experiments, the fatigue-induced loss of torque complexity occurred exclusively during contractions performed above the CT. <\/jats:p>","DOI":"10.1152\/ajpregu.00019.2016","type":"journal-article","created":{"date-parts":[[2016,4,21]],"date-time":"2016-04-21T14:55:39Z","timestamp":1461250539000},"page":"R1144-R1153","source":"Crossref","is-referenced-by-count":48,"title":["Loss of knee extensor torque complexity during fatiguing isometric muscle contractions occurs exclusively above the critical torque"],"prefix":"10.1152","volume":"310","author":[{"given":"Jamie","family":"Pethick","sequence":"first","affiliation":[{"name":"Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Samantha L.","family":"Winter","sequence":"additional","affiliation":[{"name":"Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, United 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