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The influence of preceding activity and muscle length on voluntary and electrically evoked contractions.

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  • معلومة اضافية
    • Abstract:
      Muscle length and preceding activity independently influence rate of torque development (RTD) and electromechanical delay (EMD), but it is unclear whether these parameters interact to optimize RTD and EMD. The purpose of this study was to determine the influence of muscle length and preceding activity on RTD and EMD during voluntary and electrically stimulated (e-stim) contractions. Participants (n = 17, males, 24 ± 3 years) performed isometric knee extensions on a dynamometer. Explosive maximal contractions were performed at 2 knee angles (35° and 100° referenced to a 0° straight leg) without preceding activity (unloaded, UNL) and with preceding activities of 20%, 40%, 60%, and 80% of maximal voluntary contraction (MVC) torque. Absolute and normalized voluntary RTD were slowed with preceding activities ≥40% MVC for long muscle lengths and all preceding activities for short muscle lengths compared with UNL (p < 0.001). Absolute and normalized e-stim RTD were slower with preceding activities ≥40% MVC compared with UNL (p < 0.001) for both muscle lengths. Normalized RTD was faster at short muscle lengths than at long muscle lengths (p < 0.001) for e-stim (∼50%) and voluntary (∼32%) UNL contractions, but this effect was not present for absolute RTD. Muscle length did not affect EMD (p > 0.05). EMD was shorter at 80% MVC compared with UNL (∼35%; p < 0.001) for both muscle lengths during voluntary but not e-stim contractions. While RTD is limited by preceding activity at both muscle lengths, long muscle lengths require greater preceding activity to limit RTD than short muscle lengths, which indicates long muscle lengths may offer a "protective effect" for RTD against preceding activity. [ABSTRACT FROM AUTHOR]
    • Abstract:
      La longueur du muscle et l'activité précédente influencent de façon indépendante le taux de développement du moment de force (« RTD ») et le délai électromécanique (« EMD »), mais il n'est pas bien établi si ces paramètres interagissent pour optimiser RTD et EMD. Cette étude a pour objectif de déterminer l'influence de la longueur du muscle et de l'activité précédente sur RTD et EMD au cours de contractions volontaires et de contractions suscitées électriquement (« e-stim »). Les participants (n = 17, hommes, 24 ± 3 ans) effectuent des extensions isométriques du genou sur un dynamomètre. Les participants effectuent des contractions maximales avec vivacité à deux angles du genou (35° et 100°, 0° correspondant à la jambe tendue) sans charge (« UNL ») et précédées d'activations : 20, 40, 60 et 80 % du moment de force maximale volontaire (« MVC »). On enregistre un ralentissement du RTD volontaire absolu et normalisé suivant les activités précédentes sollicitant ≥40 % MVC, muscle allongé et à toutes les activités précédentes, muscle raccourci, comparativement à UNL (p < 0,001). Le RTD e-stim, absolu et normalisé, est plus lent aux deux longueurs du muscle quand les activités précédentes sollicitent ≥40 % MVC comparativement à UNL (p < 0,001). Le RTD normalisé est plus rapide (p < 0,001) quand le muscle est raccourci comparativement au muscle allongé dans les conditions e-stim (∼50 %) et volontaire (∼32 %) sans charge (UNL), mais cet effet est absent en ce qui concerne le RTD absolu. La longueur du muscle n'influe pas sur EMD (p > 0,05). À 80 % MVC, EMD est plus court comparativement à UNL (∼35 %; p < 0,001) aux deux longueurs du muscle au cours des contractions volontaires, mais pas des contractions suscitées électriquement. Même si le RTD est limité par l'activité précédente aux deux longueurs du muscle, un muscle allongé requiert une plus grande activité précédente pour limiter le RTD comparativement à un muscle raccourci; par conséquent, un muscle allongé semble procurer un « effet protecteur » au RTD en présence d'une activité précédente. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
    • Abstract:
      Copyright of Applied Physiology, Nutrition & Metabolism is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
    • Author Affiliations:
      1Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
    • ISSN:
      1715-5312
    • Accession Number:
      10.1139/apnm-2018-0104
    • Accession Number:
      134846391
  • Citations
    • ABNT:
      DEBENHAM, M. I. B.; POWER, G. A. The influence of preceding activity and muscle length on voluntary and electrically evoked contractions. Applied Physiology, Nutrition & Metabolism, [s. l.], v. 44, n. 3, p. 301–308, 2019. DOI 10.1139/apnm-2018-0104. Disponível em: http://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=asn&AN=134846391&custid=s8280428. Acesso em: 29 maio. 2020.
    • AMA:
      Debenham MIB, Power GA. The influence of preceding activity and muscle length on voluntary and electrically evoked contractions. Applied Physiology, Nutrition & Metabolism. 2019;44(3):301-308. doi:10.1139/apnm-2018-0104.
    • APA:
      Debenham, M. I. B., & Power, G. A. (2019). The influence of preceding activity and muscle length on voluntary and electrically evoked contractions. Applied Physiology, Nutrition & Metabolism, 44(3), 301–308. https://doi.org/10.1139/apnm-2018-0104
    • Chicago/Turabian: Author-Date:
      Debenham, Mathew I.B., and Geoffrey A. Power. 2019. “The Influence of Preceding Activity and Muscle Length on Voluntary and Electrically Evoked Contractions.” Applied Physiology, Nutrition & Metabolism 44 (3): 301–8. doi:10.1139/apnm-2018-0104.
    • Harvard:
      Debenham, M. I. B. and Power, G. A. (2019) ‘The influence of preceding activity and muscle length on voluntary and electrically evoked contractions’, Applied Physiology, Nutrition & Metabolism, 44(3), pp. 301–308. doi: 10.1139/apnm-2018-0104.
    • Harvard: Australian:
      Debenham, MIB & Power, GA 2019, ‘The influence of preceding activity and muscle length on voluntary and electrically evoked contractions’, Applied Physiology, Nutrition & Metabolism, vol. 44, no. 3, pp. 301–308, viewed 29 May 2020, .
    • MLA:
      Debenham, Mathew I. B., and Geoffrey A. Power. “The Influence of Preceding Activity and Muscle Length on Voluntary and Electrically Evoked Contractions.” Applied Physiology, Nutrition & Metabolism, vol. 44, no. 3, Mar. 2019, pp. 301–308. EBSCOhost, doi:10.1139/apnm-2018-0104.
    • Chicago/Turabian: Humanities:
      Debenham, Mathew I.B., and Geoffrey A. Power. “The Influence of Preceding Activity and Muscle Length on Voluntary and Electrically Evoked Contractions.” Applied Physiology, Nutrition & Metabolism 44, no. 3 (March 2019): 301–8. doi:10.1139/apnm-2018-0104.
    • Vancouver/ICMJE:
      Debenham MIB, Power GA. The influence of preceding activity and muscle length on voluntary and electrically evoked contractions. Applied Physiology, Nutrition & Metabolism [Internet]. 2019 Mar [cited 2020 May 29];44(3):301–8. Available from: http://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=asn&AN=134846391&custid=s8280428