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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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THE EFFECT OF STIMULUS ANTICIPATION ON THE INTERPOLATED TWITCH TECHNIQUE |
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Duane C. Button and David G. Behm 
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School of Human Kinetics and Recreation , Memorial University of Newfoundland, St. John's, Newfoundland, Canada |
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© Journal of Sports Science and Medicine (2008) 7, 520 - 524 Search Google Scholar for Citing Articles |
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| ABSTRACT | |||
| The objective of this study was to investigate the effect of expected
and unexpected interpolated stimuli (IT) during a maximum voluntary contraction
on quadriceps force output and activation. Two groups of male subjects who
were either inexperienced (MI: no prior experience with IT tests) or experienced
(ME: previously experienced 10 or more series of IT tests) received an expected
or unexpected IT while performing quadriceps isometric maximal voluntary
contractions (MVCs). Measurements included MVC force, quadriceps and hamstrings
electromyographic (EMG) activity, and quadriceps inactivation as measured
by the interpolated twitch technique (ITT). When performing MVCs with the
expectation of an IT, the knowledge or lack of knowledge of an impending
IT occurring during a contraction did not result in significant overall
differences in force, ITT inactivation, quadriceps or hamstrings EMG activity.
However, the expectation of an IT significantly (p < 0.0001) reduced
MVC force (9.5%) and quadriceps EMG activity (14.9%) when compared to performing
MVCs with prior knowledge that stimulation would not occur. While ME exhibited
non-significant decreases when expecting an IT during a MVC, MI force and
EMG activity significantly decreased 12.4% and 20.9% respectively. Overall,
ME had significantly (p < 0.0001) higher force (14.5%) and less ITT inactivation
(10.4%) than MI. The expectation of the noxious stimuli may account for
the significant decrements in force and activation during the ITT.
Key words: Muscle activation, electromyography, evoked stimulation. |
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