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PLoS One. 2014 Nov 4;9(11):e111521. doi: 10.1371/journal.pone.0111521. eCollection 2014.

Hormonal and neuromuscular responses to mechanical vibration applied to upper extremity muscles.

Author information

1
Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila Italy.
2
Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy.
3
Laboratory of Chemical-Clinical and Microbiological Analysis, Giulianova Hospital, Teramo, Italy.
4
Department of Biomechanics, Faculty of Physical Education and Sport Sciences, Semmelweis University, Budapest, Hungary.

Abstract

OBJECTIVE:

To investigate the acute residual hormonal and neuromuscular responses exhibited following a single session of mechanical vibration applied to the upper extremities among different acceleration loads.

METHODS:

Thirty male students were randomly assigned to a high vibration group (HVG), a low vibration group (LVG), or a control group (CG). A randomized double-blind, controlled-parallel study design was employed. The measurements and interventions were performed at the Laboratory of Biomechanics of the University of L'Aquila. The HVG and LVG participants were exposed to a series of 20 trials ×10 s of synchronous whole-body vibration (WBV) with a 10-s pause between each trial and a 4-min pause after the first 10 trials. The CG participants assumed an isometric push-up position without WBV. The outcome measures were growth hormone (GH), testosterone, maximal voluntary isometric contraction during bench-press, maximal voluntary isometric contraction during handgrip, and electromyography root-mean-square (EMGrms) muscle activity (pectoralis major [PM], triceps brachii [TB], anterior deltoid [DE], and flexor carpi radialis [FCR]).

RESULTS:

The GH increased significantly over time only in the HVG (P = 0.003). Additionally, the testosterone levels changed significantly over time in the LVG (P = 0.011) and the HVG (P = 0.001). MVC during bench press decreased significantly in the LVG (P = 0.001) and the HVG (P = 0.002). In the HVG, the EMGrms decreased significantly in the TB (P = 0.006) muscle. In the LVG, the EMGrms decreased significantly in the DE (P = 0.009) and FCR (P = 0.006) muscles.

CONCLUSION:

Synchronous WBV acutely increased GH and testosterone serum concentrations and decreased the MVC and their respective maximal EMGrms activities, which indicated a possible central fatigue effect. Interestingly, only the GH response was dependent on the acceleration with respect to the subjects' responsiveness.

PMID:
25368995
PMCID:
PMC4219718
DOI:
10.1371/journal.pone.0111521
[Indexed for MEDLINE]
Free PMC Article

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