Friday, 26 April 2013

Two new papers

Apologies for radio silence. It has been a buys few months with loads happening. I have now left Team GB and moved on to new adventures (I will talk about it soon). In the meantime two papers have been recently published and the abstracts are here.

 

Horm Metab Res. 2013 Apr 15. [Epub ahead of print]

Combination of External Load and Whole Body Vibration Potentiates the GH-releasing Effect of Squatting in Healthy Females.

Giunta M, Rigamonti AE, Agosti F, Patrizi A, Compri E, Cardinale M, Sartorio A.

Source

Istituto Auxologico Italiano, IRCCS, Laboratorio Sperimentale di Ricerche Auxo-endocrinologiche, Milan and Piancavallo (VB), Italy.

Abstract

In recent years, whole body vibration (WBV) has become an efficient complement or alternative to resistance training. Very limited data on the effects of different WBV protocols on anabolic hormones are available. In this study, we compared the growth hormone (GH), blood lactate (LA), and cortisol responses to different protocols involving WBV. Six healthy women recreationally active performed 10 sets of 12 dynamic squats in the following conditions: squatting alone (S), squatting+vibration (SV), squatting+external load (SE), and squatting+external load+vibration (SEV). All responses at the different stimuli determined acute increases in GH, cortisol, and LA. In particular, GH secretion significantly increased in all 4 conditions immediately after the exercise session compared to other time points. Furthermore, a significantly larger increase was identified following SEV as compared to the other conditions. Cortisol concentrations significantly decreased after S, SV and SE whereas they increased significantly following SEV. LA peaks occurred immediately at the end of each condition. However it reached statistical significance only following SEV. The results of our study demonstrate that the combination of squatting+external load+vibration (SEV) could represent the most suitable modality to potentiate the somatotropic function and, indirectly, to obtain an increase in muscle strength and positive changes in the body composition. Further studies are necessary in order to determine the chronic effects of this exercise modality on the hormonal profile.

 

Eur J Appl Physiol. 2013 Jan 24. [Epub ahead of print]

Neuromuscular fatigue induced by whole-body vibration exercise.

Maffiuletti NA, Saugy J, Cardinale M, Micallef JP, Place N.

Source

Neuromuscular Research Laboratory, Schulthess Clinic, Lengghalde 2, 8008, Zurich, Switzerland, nicola.maffiuletti@kws.ch.

Abstract

The aim of this study was to examine the magnitude and the origin of neuromuscular fatigue induced by half-squat static whole-body vibration (WBV) exercise, and to compare it to a non-WBV condition. Nine healthy volunteers completed two fatiguing protocols (WBV and non-WBV, randomly presented) consisting of five 1-min bouts of static half-squat exercise with a load corresponding to 50 % of their individual body mass. Neuromuscular fatigue of knee and ankle muscles was investigated before and immediately after each fatiguing protocol. The main outcomes were maximal voluntary contraction (MVC) torque, voluntary activation, and doublet peak torque. Knee extensor MVC torque decreased significantly (P < 0.01) and to the same extent after WBV (-23 %) and non-WBV (-25 %), while knee flexor, plantar flexor, and dorsiflexor MVC torque was not affected by the treatments. Voluntary activation of knee extensor and plantar flexor muscles was unaffected by the two fatiguing protocols. Doublet peak torque decreased significantly and to a similar extent following WBV and non-WBV exercise, for both knee extensors (-25 %; P < 0.01) and plantar flexors (-7 %; P < 0.05). WBV exercise with additional load did not accentuate fatigue and did not change its causative factors compared to non-WBV half-squat resistive exercise in recreationally active subjects.

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