Paper Information

Title:  ECCENTRIC TASK DECREASES RECOVERY OF MYOELECTRICAL ACTIVITY AFTER FATIGUING CONTRACTION
Type: SPEECH
Author(s): HEDAYATPOUR N.A.,FARINA D.,FALLA D.,ARENDT NIELSEN L.
 
 
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2007Volume 18
 
 
Abstract: 

Introduction: Disruptive influences of eccentric tasks on muscle fiber have been reported. Damage to skeletal muscle fiber may effect on normal recovery of membrane electrical activity after fatiguing task.
Methods: Ten healthy, male subjects (age, mean±SD, 23.3±4.2 yr) participated in the study. Bipolar surface EMG signals were detected from the vastus medialis (VM) and vastus lateralis (VL) muscles with 6 pairs of electrodes. Electrode pairs were located at 10%, 20% and 30%, of the distance between the anterior superior iliac spine and the medial and lateral border of the patella at a site bisecting 20% and 80% of the half circumference of the thigh for VM and VL respectively. A KinCom isokinetic dynamometer was used to induce injury to quadriceps with a protocol of eccentric exercise. Subjects performed an isometric knee extension at 40% of the maximal force (MVC) until task failure at baseline (pre exercise), just after, 24 hours and 48 hours following the eccentric task. Average rectified value (ARV) and mean power spectrum frequency (MPF) was estimated from the EMG signals in time intervals with a duration equal to 10% of the time to task failure. For the recovery phase EMG signals were recorded at intervals of 1 min for 15 min, during 2-s contractions at the same force level as during the fatiguing task.
Results: Maximum knee extension force and time to task failure were reduced just after, 24 hours and 48 hours following eccentric task (P<0.05). EMG MPF recovery was also lower after eccentric task with respect to baseline value (ANOVA: F=11.7, P=0.000; SNK: P<0.05), compared with pre-exercise step. Moreover muscle and their location were non-uniformly effected by eccentric task (F =1.42, P<0.05).
Conclusion: Results may indicate a malfunction in mechanisms associated with recovery of myoelectrical activity such as Na+-K+-pump and/or membrane ionic permeability changes in response to lengthening contraction.

 
Keyword(s): 
 
Yearly Visit 3  
 
Latest on Blog
Enter SID Blog