Hormonal responses to whole-body vibration in men

Abstract

The aim of this study was to evaluate the acute responses of blood hormone concentrations and neuromuscular performance following whole-body vibration (WBV) treatment. Fourteen male subjects [mean (SD) age 25 (4.6) years] were exposed to vertical sinusoidal WBV, 10 times for 60 s, with 60 s rest between the vibration sets (a rest period lasting 6 min was allowed after 5 vibration sets). Neuromuscular performance tests consisting of counter-movement jumps and maximal dynamic leg presses on a slide machine, performed with an extra load of 160% of the subjects body mass, and with both legs were administered before and immediately after the WBV treatment. The average velocity, acceleration, average force, and power were calculated and the root mean square electromyogram (EMGrms) were recorded from the vastus lateralis and rectus femoris muscles simultaneously during the leg-press measurement. Blood samples were also collected, and plasma concentrations of testosterone (T), growth hormone (GH) and cortisol (C) were measured. The results showed a significant increase in the plasma concentration of T and GH, whereas C levels decreased. An increase in the mechanical power output of the leg extensor muscles was observed together with a reduction in EMGrms activity. Neuromuscular efficiency improved, as indicated by the decrease in the ratio between EMGrms and power. Jumping performance, which was measured using the counter-movement jump test, was also enhanced. Thus, it can be argued that the biological mechanism produced by vibration is similar to the effect produced by explosive power training (jumping and bouncing). The enhancement of explosive power could have been induced by an increase in the synchronisation activity of the motor units, and/or improved co-ordination of the synergistic muscles and increased inhibition of the antagonists. These results suggest that WBV treatment leads to acute responses of hormonal profile and neuromuscular performance. It is therefore likely that the effect of WBV treatment elicited a biological adaptation that is connected to a neural potentiation effect, similar to those reported to occur following resistance and explosive power training. In conclusion, it is suggested that WBV influences proprioceptive feedback mechanisms and specific neural components, leading to an improvement of neuromuscular performance. Moreover, since the hormonal responses, characterised by an increase in T and GH concentration and a decrease in C concentration, and the increase in neuromuscular effectiveness were simultaneous but independent, it is speculated that the two phenomena might have common underlying mechanisms.

Immediate effects of whole body vibration on patellar tendon properties and knee extension torque

“…A small decrease in isometric torque was observed at knee angle of 60° in the WBV group and suggests that a certain fatigue was caused by vibration. This is further supported by other publications with comparable vibration settings (3-to-10 times 60-second periods of isometric squatting at 70-to-50° of knee flexion; vibration frequency: 30 Hz; vibration amplitude: 4-8 mm), reporting decreases in muscular strength after a single session of WBV (de Ruiter et al 2003;Erskine et al 2007;Jordan et al 2010) Conversely, some authors have reported strength increases immediately after WBV (Bosco et al 1999;Bosco et al 2000;Mc Bride et al 2010). However, this phenomenon only seems ephemeral, as suggested by its disappearance after a few minutes (Stewart et al 2009;Torvinen et al 2002).…”

“…Earlier studies have found increased muscular strength and power after a single bout of vibration exercise (Bosco et al 1999;Bosco et al 2000). However, discrepant findings have since been reported and the immediate effects of WBV on neuromuscular performance are still debated.…”

“…However, discrepant findings have since been reported and the immediate effects of WBV on neuromuscular performance are still debated. For instance, authors observed gains in jump performance (Bosco et al 2000;Colson and Petit 2013) and lower body strength (Mc Bride et al 2010;Stewart et al 2009;Torvinen et al 2002) but others failed to see any improvement in muscular function (Kelly et al 2010;Yeung et al 2014) or even found reductions in maximum torque following a single WBV intervention (de Ruiter et al 2003;Erskine et al 2007;Jordan et al 2010). These inconsistent findings are often explained by differences in vibration parameters or by the time elapsed between the WBV session and the measurements (Stewart et al 2009;Torvinen et al 2002).…”

Determining the Optimal Whole-Body Vibration Dose–response Relationship for Muscle Performance

“…Several studies have looked at the effects of WBV on muscle performance. However, the results are not clear and are sometimes contradictory (9,(13)(14)(15)17,21,22,25,35,38,39 AU7 ). The variability in the protocols used by different authors may explain the inconsistency of the results presented in published studies (13).…”

To Compare the Effect of Vibration Therapy and Massage in Prevention of Delayed Onset Muscle Soreness (DOMS)

“…On application of vibration, the motor neuron may become synchronized and result in more force production of the muscle group [30,31]. Vibration may causes motor unit activation, synchronization between muscle spindles, reflexive recruitment of previously inactive motor units which leads to more force production for the exercise [12].…”