Document Detail


Inter-relationships between machine squat-jump strength, force, power and 10 m sprint times in trained sportsmen.
MedLine Citation:
PMID:  20308970     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
AIM: Strength and conditioning practitioners appear focussed on developing maximal strength based on the premise that it underpins explosive muscular performance. Investigation into the relationship between strength and a multitude of explosive power measures is limited though. Furthermore, the relationship of explosive force and power with functional performance is unclear.
METHODS: We examined the inter-relationships between maximal strength and explosive measures of force and power at different loads. Also investigated were the relationships between explosive measures and 10-m sprinting ability. Forty elite-level well-trained rugby union and league athletes performed 10-m sprints followed by bilateral concentric-only machine squat-jumps at 20 and 80%1RM. The magnitudes of the inter-relationships between groups of force measures, power measures and sprint times were interpreted using Pearson correlation coefficients, which had uncertainty (90% confidence limits) of approximately +/-0.25. Measures investigated included peak force, peak power, rate of force development, and some of Zatsiorsky's explosive measures, all expressed relative to body mass.
RESULTS: The relationship between maximal strength and peak power was moderate at 20 %1RM (r=0.32) but trivial at 80 %1RM (r=-0.03). Practically no relationship between any of the explosive measures and 10-m sprint ability was observed (r=-0.01 to 0.06).
CONCLUSION: Although correlations do not imply cause and effect, we speculate that the common practice of focussing on high levels of maximal strength in a machine squat to improve power output may be misguided. Our results also cast doubt on the efficacy of increasing explosive force and power in a machine squat-jump with the intention of improving sprint ability in well-trained athletes.
Authors:
Nigel K Harris; J B Cronin; W G Hopkins; K T Hansen
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of sports medicine and physical fitness     Volume:  50     ISSN:  0022-4707     ISO Abbreviation:  J Sports Med Phys Fitness     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-03-23     Completed Date:  2011-01-06     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0376337     Medline TA:  J Sports Med Phys Fitness     Country:  Italy    
Other Details:
Languages:  eng     Pagination:  37-42     Citation Subset:  IM    
Affiliation:
Sport Performance Research Institute New Zealand, AUT University, Auckland, New Zealand. nigel.harris@aut.ac.nz
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MeSH Terms
Descriptor/Qualifier:
Adult
Biomechanics
Confidence Intervals
Football / physiology*
Humans
Leg / physiology*
Male
Muscle Contraction / physiology*
Muscle Strength / physiology*
Muscle, Skeletal / physiology*
Pilot Projects
Running / physiology*
Statistics as Topic
Time Factors
Weight Lifting / physiology*

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


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