Document Detail


The effects of fatigue of the plantar flexors on peak torque and voluntary activation in untrained and resistance-trained men.
MedLine Citation:
PMID:  20512071     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Hartman, MJ, Ryan, ED, Cramer, JT, and Bemben, MG. The effects of fatigue of the plantar flexors on peak torque and voluntary activation in untrained and resistance-trained men. J Strength Cond Res 25(2): 527-532, 2011-The purpose of this study was to compare the effects of fatigue of the plantar flexors on peak torque and voluntary activation in untrained (UT) and resistance-trained (RT) men. Six men with no previous resistance training experience and 8 men with similar histories of chronic resistance training (9.8 ± 5.9 years, 3.8 ± 0.7 days/week) volunteered for this study. Subjects performed isometric maximal voluntary contractions (MVCs) before and immediately after unilateral dynamic isotonic contractions performed at 40% of MVC until volitional exhaustion. Voluntary activation of the plantar flexors was assessed using the interpolated twitch method (ITT) and central activation ratio (CAR). Surface electromyographic (EMG) amplitude of the soleus and medial gastrocnemius (MG) was measured during the MVC. There were significant reductions in MVC torque in both UT and RT groups after the fatiguing exercise (-10.7 ± 6.8%, p < 0.02; -9.1 ± 8.7%, p < 0.02, respectively), with no difference in the number of repetitions performed between groups. The UT and RT men experienced a significant decrease in ITT after the fatiguing exercise bout (-14.2 ± 11.8%, p = 0.03; -7.8 ± 9.3%, p = 0.045, respectively). The UT group experienced a significant decrease in CAR (99.5 ± 0.8% to 91.4 ± 6.4%, p = 0.025) with no change (p > 0.05) in the RT group. There was also a fatigue-induced decrease in normalized EMG amplitude for the soleus and MG muscles in both groups (p < 0.05). However, no differences were determined between groups for ITT, CAR, or EMG. Despite similar reductions in MVC torque postexercise, the UT men had a significant decrease in CAR and experienced nearly twice the decline in ITT than the RT men. These results indicate that the neural adaptations associated with chronic resistance training may lead to less susceptibility to central fatigue as measured by ITT and CAR.
Authors:
Michael J Hartman; Eric D Ryan; Joel T Cramer; Michael G Bemben
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of strength and conditioning research / National Strength & Conditioning Association     Volume:  25     ISSN:  1533-4287     ISO Abbreviation:  J Strength Cond Res     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-01-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9415084     Medline TA:  J Strength Cond Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  527-32     Citation Subset:  IM    
Affiliation:
1Department of Kinesiology, Human Performance Research Laboratory, Texas Wesleyan University, Fort Worth, Texas; 2School of Applied Health, Applied Musculoskeletal & Human Physiology Research Lab, Oklahoma State University, Stillwater, Oklahoma; 3Department of Health and Exercise Science, Biophysics Laboratory, University of Oklahoma, Norman, Oklahoma; and 4Department of Health and Exercise Science, Neuromuscular Research Laboratory, University of Oklahoma, Norman, Oklahoma.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Effects of heat exposure and 3% dehydration achieved via hot water immersion on repeated cycle sprin...
Next Document:  Tissue Banking of Diagnostic Lung Cancer Biopsies for Extraction of High Quality RNA.