University of SaskatchewanHARVEST
  • Login
  • Submit Your Work
  • About
    • About HARVEST
    • Guidelines
    • Browse
      • All of HARVEST
      • Communities & Collections
      • By Issue Date
      • Authors
      • Titles
      • Subjects
      • This Collection
      • By Issue Date
      • Authors
      • Titles
      • Subjects
    • My Account
      • Login
      JavaScript is disabled for your browser. Some features of this site may not work without it.
      View Item 
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item

      Neuro-Mechanical Analysis of Eccentric Overload of Elbow Flexors

      Thumbnail
      View/Open
      LEAL-THESIS.pdf (2.405Mb)
      Date
      2014-06-20
      Author
      Leal, Frederico
      Type
      Thesis
      Degree Level
      Masters
      Metadata
      Show full item record
      Abstract
      Eccentric overload in training settings utilizes loads higher than concentric one repetition maximum (1RM). There is no clear definition of eccentric “failure” or 1RM using conventional weights, so eccentric 1RM is estimated to be between 145-190% concentric 1RM. Historically, the highest intensity used for eccentric overload is typically 120% of concentric 1RM despite little research using conventional weights with higher eccentric intensities. The purpose of this study was to conduct an exploratory neuro-mechanical analysis of different intensities of elbow flexors eccentric overload using free weights by examining angular kinematics during contraction. Twenty male participants with weight training experience had unilateral concentration curl isometric peak torque assessed on a Humac Norm Dynamometer and concentric 1RM assessed with dumbbells while biceps brachii electromyography (EMG) and elbow joint angle were recorded. Angles were recorded using a custom made electrogoniometer and elbow joint torque was estimated using inverse dynamics. Participants were randomly assigned in counter balanced order to perform eccentric actions at 120%, 140%, 150%, 160% and 170% concentric 1RM with 4 minutes rest between. Variables included peak torque, angular velocity at peak torque, impulse, power, mean EMG, and EMG normalized to peak. Data were analyzed using repeated measures ANOVA or a Friedman test. Angular velocity at peak torque was significantly lower for 120% (65.3 ± 40.8°/s) compared to all other conditions (range: 65.3 ± 40.8 to 162.1 ± 75.2°/s; p<0.01). Peak torque for all conditions (range: 98.2 ± 16.2 to 108.2 ± 21.6 Nm) was significantly higher than isometric peak torque (77.4 ± 16.8Nm; p<0.05). Peak torque at 160% (108.2 ± 21.6Nm) was significantly higher than at 120% (98.2 ± 16.2Nm; p<0.05). Power for 140-170% (range: 166.2 ± 85.7W to 265.8 ± 111.3W) was significantly higher than power at 120% (79.9 ± 66.8W; p<0.05). Impulse was highest at 120% (56.1 ± 54.6Nms) compared to all other conditions (range: 56.2 ± 54.6 to 9.6 ± 3.8Nms; p≤0.05). Impulse at 140% (20.6 ± 11.8Nms) was significantly higher than 170% (9.6 ± 3.8Nms; p<0.05). Isometric mean EMG (0.792 ± 0.285 mV) was significantly higher than all eccentric conditions (range: 0.654 ± 0.313 to 0.533 ± 0.259mV; p<0.05) with no difference between eccentric conditions for mean EMG or EMG normalized to peak. It was concluded that compared to 120%, eccentric overload with intensity ranging from 140-170% concentric 1RM involves minimal increases in peak torque and no change in EMG activation. Intensities above 120% enhance power and decrease impulse. This research has implications on future training prescription of eccentric exercise.
      Degree
      Master of Science (M.Sc.)
      Department
      Kinesiology
      Program
      Kinesiology
      Supervisor
      Farthing, Jonathan P.
      Committee
      Lanovaz, Joel L.; Chilibeck, Philip D.
      Copyright Date
      January 2013
      URI
      http://hdl.handle.net/10388/ETD-2013-01-908
      Subject
      muscle hypertrophy, muscle strength, free weights, electrogoniometry, dumbbells
      Collections
      • Graduate Theses and Dissertations
      University of Saskatchewan

      University Library

      The University of Saskatchewan's main campus is situated on Treaty 6 Territory and the Homeland of the Métis.

      © University of Saskatchewan
      Contact Us | Disclaimer | Privacy