Acute changes in neuromuscular excitability after exhaustive whole body vibration exercise as compared to exhaustion by squatting exercise
The effects of hard squatting exercise with whole body vibration and without whole body vibration on neuromuscular function were tested in 19 healthy young volunteers. Before and after the exercise, three different tests were performed: maximum serial jumping for 30 s[econds], electromyography during isometric knee extension at 70% of the maximum voluntary torque, and the quantitative analysis of the patellar tendon reflex. With whole body vibration and without whole body vibration values, there was no
difference found under baseline conditions. Time to exhaustion was significantly shorter in whole body vibration than without whole body vibration, but blood lactate and subjective rate of perceived exertion at the termination of exercise indicate comparable levels of fatigue. After the exercise, comparable effects were observed on jump height, ground contact time, and isometric torque [refers to the force the researcher is studying, for various joint movements while person is standing still]. The vastus lateralis mean frequency during isometric torque, however, was higher after whole body vibration than without whole body vibration. Likewise, the tendon reflex amplitude [a measurement] was significantly greater after whole body vibration than without whole body vibration. [Those conducting the study were still skeptical about the use of whole body vibration. This study only proves to the author of this blog that whole body vibration is less wear and tear on the body.]
Institut für Physiologie, Freie UniversitätBerlin,Arnimallee,Berlin,Germany. firstname.lastname@example.org
Acute effects of whole-body vibration on muscle activity, strength, and power
variables in both the IS and CMJ, and were exposed to a 30-second bout of WBV or sham. Subjects were tested immediately following the WBV as well as 5, 15, and 30 minutes post treatment. WBV resulted in a significantly higher JH during the CMJ immediately following WBV, as compared with the sham procedure. No significant differences were observed in CMJ PP; PF during IS or IEMG of the vastus medialis, vastus lateralis, or biceps femoris during the CMJ; or IS between vibration and sham treatments. Their conclusion was not very conclusive because they indicated that future research was warranted addressing the influence of various protocols of WBV (i.e., duration, amplitude, frequency) on athletic performance.
Neuromuscular Laboratory, Department of Health, Leisure & Exercise Science, Appalachian State University, Boone, North Carolina 28608, USA.
Acute physiological effects of exhaustive whole-body
vibration exercise in man
“Vibration exercise (VE) is a new neuromuscular training method which is applied in athletes as well as in prevention and therapy of osteoporosis [the thinning of bone tissue and loss of bone density over time]. The present study explored the physiological mechanisms of fatigue by VE in 37 young healthy subjects. Exercise and cardiovascular data were compared to progressive bicycle ergometry until exhaustion. The reproducibility [the degree of agreement between measurements or observations conducted on replicate specimens in different locations by different people] in the two VE sessions was quite good: for heart rate, oxygen uptake and reduction in jump height . . . . VE can be well controlled in terms of these parameters. The study found that exhaustive whole-body VE elicits a mild cardiovascular exertion, and that neural as well as muscular mechanisms of fatigue may play a role.”
“Vibration exercise (VE) . . . elicits neuromuscular training reflectorily [reflex /re·flex/ (re´fleks) a reflected action or movement; the sum total of any particular automatic response mediated by the nervous system], without much effort and in short periods. . . . VE has been reported as a successful countermeasure against loss of bone mineral (Flieger et al., 1998). . . . depending on the frequency of vibration, VE renders specific training of type II muscle fibres possible. Several chronic training studies are being conducted in various fields, including sports and training sciences, geriatrics and treatment of osteoporosis (Rubinet al., 1998; Wilhelm et al., 1998; Bosco et al., 1999).”
The institute performing this study “worked with a prototype, in which a platform vibrates around a horizontal rotation axis (i.e., Novotec, Pforzheim, Germany). Exercise is usually performed with both legs, the feet posed equally distant on either side of the rotation axis [platform]. Hereby, extensor [Extension is the opposite of flexion; a straightening movement that increases the angle between body parts i.e. In a conventional handshake, the fingers are fully extended] and flexor [Flexion is the bending movement that decreases the angle between two parts i.e. Bending the elbow, or clenching a hand into a fist, are examples of flexion] contractions alternate continuously in the left and the right legs. There is no direct vertical acceleration to the body’s center of gravity. This reduces passive forces to the joints, but elicits reflexes to stabilize the body posture.”
In the previous experiments this institute studied, they ascertained that “VE elicits muscle contractions by recording an electro-myogram (EMG). Moreover, [they found that] oxygen uptake and metabolism typically increased during VE as compared to squatting without vibration (unpublished data).” In a more recent study that was performed, they explored the limits, i.e. the exertion and fatigue effects of exhaustive VE, and how far these limits are reproducible in subsequent exercise sessions. They used progressive bicycle ergometry as a comparison.
The study showed that the participants “heart rate increased significantly less in VE Sessions 1 and 2 than in bicycle ergometry. Control values were higher before VE than before bicycle ergometry. No difference was found in the recovery values. Similar to heart rate, the Oxygen uptake was significantly lower during VE than during bicycle ergometry.”
“Systolic blood pressure increased significantly during bicycle ergometry and VE.” When participants were tested, the rise in blood pressure was not as large on the VE as it was on the bicycle ergometry. They found that the participants’ diastolic blood pressure was decreased after VE, but not after bicycle ergometry.
“Treatment and prevention of osteoporosis by physical exercise is a new therapeutic concept (Calmels et al., 1995).'” Generally, the subjects became acquainted very rapidly with this exercise. By the second VE session, they were standing confidently and safely on the platform. Exercise time was longer during the second VE session than in the first session. . . . “At the termination of exercise, i.e. after about 5 minutes, the subjects appeared to be quite as exerted by VE as after [a] 12-minute session [of] bicycle ergometry.”
” Systolic arterial blood pressure, which could not be measured during VE, was found to have increased after it, but less so than after bicycle ergometry. In contrast, diastolic blood pressure had decreased only after VE.”
“The fatigue in VE therefore appears to be caused not by insufficiency of cardiac output (as in exhaustive bicycle ergometry), but rather occurs in the neuromuscular system.”
“. . . vibration exercise is a new strategy in eliciting muscular contraction by reflexes. It therefore may allow the combination of voluntary and involuntary muscle work. The present investigation has shown that, even if performed to exhaustion, cardio-vascular effects of VE are mild. . . .In consequence, the risk expected when VE is applied in the elderly is negligible. ”
The institute will investigate further studies on itching erythema and oedema of the skin over activated muscles and the mechanisms of fatigue, which seem to bear neuronal and muscular components.
J. Rittweger1,2, G. Beller2 and D. Felsenberg2
1Institute of Physiology, Freie UniversitaÈ t Berlin, Arnimallee 22, 14195 Berlin, Germany, and 2Osteoporosis Research Group, Freie UniversitaÈ t Berlin, University Hospital Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany
Received 29 June 1999; accepted 9 November 1999
Correspondence: Dr JoÈ rn Rittweger, Institut fuÈ r Physiologie, Arnimallee 22, 14195 Berlin, Germany