Research article - (2004)03, 16 - 22
The Influence of Vibration on Muscle Activation and Rate of Force Development during Maximal Isometric Contractions
Brendan Humphries1,, Geoff Warman2, Jason Purton3, Tim L. A. Doyle4, Eric Dugan5
1School of Health Science, Charles Darwin University, Australia
2School of Human Movement Studies, University of Queensland, Australia
3School of Health and Human Performance, Central Queensland University, Australia
4School of Biomedical and Sports Science, Edith Cowan University, Australia
5Biomechanics Laboratory, Ball State University, Indiana, USA

Brendan Humphries
✉ School of Health Science, Charles Darwin University, Northern Territory, 0815 Australia.
Email: Brendan.Humphries@cdu.edu.au
Received: 25-04-2003 -- Accepted: 04-12-2003
Published (online): 01-03-2004

ABSTRACT

At present there appears to be a need for research conducted on the effects of vibration on the contractile ability of skeletal muscle tissue. The aim of this study was to address this issue by examining the effects of a superimposed muscle/tendon vibration at 50.42±1.16 Hz (acceleration 13.24 ± 0.18ms-2: displacement ≈5mm) on muscular activation and maximal isometric contraction. Sixteen participants with a mean age, body mass, and height of 22 ± 4.4 years, 73.2 ± 11.7 kg and 173.1 ± 9.7 cms, respectively, were recruited for this study. Electromyography and accelerometry from the rectus femoris, and maximal isometric force data characteristics were collected from the dominant limb under conditions of vibration, and no-vibration. A superimposed 50 Hz vibration was used during the contraction phase for the maximal isometric leg extension for the condition of vibration. A one-way ANOVA revealed no significant (p > 0.05) differences between the vibration and no-vibration conditions for peak normalized EMGRMS (84.74% Vs 88.1%) values. An ANOVA revealed significant (p > 0.05) differences between the peak fundamental frequencies of the FFT between the conditions vibration (27.1 ± 12.2 Hz) and no-vibration (9.8 ± 3.5 Hz). Peak isometric force, peak rate of force development, rate of force development at times 0.05, 0.01, 0.1, 0.5 seconds, and rate of force development at 50, 75, and 90% of peak force were not significantly different. The results of this study suggest that the application of vibration stimulation at 50 Hz during the contraction does not contribute to muscle activation, or enhance force production for maximal isometric contractions.

Key words: Strength, oscillations, isometric, peak, muscle activation

Key Points
  • The application of a vibratory stimulation to the human body increases the normal acceleration resulting in an increase in force and a change in performance
  • This study was to address this issue by examining the effects of a direct superimposed muscle/tendon vibration at 50 Hz on isometric strength characteristics
  • No improvement or change in isometric force or rate of force development
  • No changes to peak normalized EMG values








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