Abstract
The present series of experiments were conducted to access the
surface EMG frequency parameters during repeated fingertip isometric
contractions to determine if they can be used as a fatigue index under specific
grip used in rock climbing. Electromyograms of the finger flexors and extensors
were characterised in ten elite climbers and ten non-climbers. The exercise
consisted in reaching 80 % of maximal isometric finger force as
quickly as possible intermittently with a 5-s contraction followed by 5-s of
rest until exhaustion (i. e. when the subject was unable to maintain
80 - 70 % MVC force range for the
5 s). The results clearly indicate that expert climbers performed
significantly greater fingertip force than sedentary subjects
(420 ± 46 N vs.
342 ± 56 N). This force was maintained during
twelve repetitions (12.88 ± 4.96) in sedentary subjects,
whereas the climbers maintained the force during nineteen repetitions
(19.33 ± 4.84). The median frequency of both the flexor
and extensor EMG power spectra decreased during fatiguing isometric
contractions, but at different rates in climbers and non-climbers. In
non-climbers, the results replicated previous findings, whereas in climbers the
results were novel.
Key words
Muscular fatigue - fingertip force - biomechanics - rock climbing
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