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This reflex activity is also referred to as a "Tonic Vibration Reflex" or 'TVR'. It is this mechanism which ensures an optimal increase in power. |
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The effect per pulsation is like that of the knee jerk reflex, which means activation of all muscles fibers (agonist and antagonists) in a way it does not exert any physical stress or load on the musculoskeletal system. It decreases the threshold of the type II muscle fibers, thus, they are recruited at the beginning of the desired motion and act together with the type I to achieve a tremendous change in the explosive power which mean a quick and strong desired motion. All this is achieved in up to 10 repetitions of 1 minute. The same synchronisation of the central nervous system happens after passing the hard work of about one-month of intensive weight training. This muscle activity can be measured by electromyography (EMG). For example, in one repetition maximum effort, the muscle(s) involved are activated voluntarily at 100%. But with Vibration Training on the NEMES BOSCO-SYSTEM, the muscles work at 200% - 300% of this 1RM activation...! But in order to get this result the user needs to know his/her exact vibration training frequency. A simple electromyography (EMG) test prior the training session will give the information which frequency to use. The NEMES BOSCO is the ONLY vibration training machine world wide, which can determine the training frequency of its user.
The facilitation of the excitability of the spinal reflex has been elicited through vibration of the quadriceps muscle (Burke et al. 1996). Lebedev and Peliakov (1991) have aIso suggested the possibility that vibrations may elicit excitatory inflow through muscle spin dle-motoneurons connections in the overall motoneuron inflow.
It has been shown that the vibration-induced activation of muscle spindle receptors not only affects the muscle to which vibration is applied, but also affects the neighbouring muscles (Kasai et al. 1992). A mechanical vibration (10-200 Hz), applied to the muscle belly or tendon can elicit a reflex contraction (Hagbarth and Eklund, 1965). This response has been named "tonic vibration reflex" (TVR). It is not known whether it can be elicited by low vibration treatment (30 Hz), even if it has been suggested to occur during whole body vibration at frequencies ranging from 1 to 30Hz (Seidel, 1988). The improvement of the muscle performance after a short period of vibration training has been quoted (Bosco et al. 1998) to be similar to what occurs after several weeks of heavy resistance training (e.g. Coyle et al. 1981, Hakkinen and Komi 1985). In fact the improvement of the muscle functions after resistance training has been attributed to the enhancement of the neuromuscular behaviour caused by the increasing activity of the higher motor centre (Milner-Brownet al., 1975). The improvement of muscle performances induced by vibration training (VT) suggests that a neural adaptation has occurred in response to the vibration treatments. In this context, the duration of the stimulus seems to be both relevant and important. The adaptive response of human skeletal muscle to simulated hyper gravity conditions (1.1g) applied for only three weeks, caused a considerable improvement in the leg extensor muscle behaviour (Bosco 1985).
After the VT period the EMG activity was found to be rather lower or to be the same as compared to the pre-treatment conditions even if, during the vibration, period an increment of neural input to the muscle occurred. In this respect the decrease in the ratio between EMG and mechanical power (EMG/P) demonstrated that VT induced an improvement of the neuromuscular efficiency of the muscles involved in the vibration treatment. Vertical jumping ability has been shown to increase following vibration treatment (Bosco et al. 1998; Bosco et al 1999). These improvements have been attributed to an enhancement of neural activity in the leg extensor muscles, together with an enhancement of the proprioceptors' feedback. During vibrations, the length of skeletal muscles changes slightly. The facilitation of the excitability of spinal reflexes has been shown to be elicited by vibrations applied to the quadriceps muscle (Burke et al. 1996). Once again, the influence of vibrations on the neural drive of the la loop can play a crucial part in enhancing jumping performance following vibration treatments. Even if the adaptive responses of neuromuscular performance as measured by vertical jump tests cannot be fully explained, it is important to consider that the effectiveness of the stimulus can have both relevance and importance. The adaptive response of human skeletal muscle to simulated hyper gravity conditions (1.1 g), applied for only three weeks, caused a drastic enhancement of the neuromuscular functions of the leg extensor muscles (Bosco 1985). The regular use of centrifugal force (2 g) for 3 months has initiated conversion of muscle fibre type (Martin and Romond, 1975). In the experiments conducted, the total length of the WBV application period was not very long (from 7 minutes to 100 minutes), but the disturbance to the gravitational field was quite consistent (5.4 g). An equivalent length and intensity of training stimulus (100 minutes) can only be reached by performing 200 drop jumps from 60 cm, twice a week for 12 months. In fact, the time spent for each drop jump is less than 200 ms, and the acceleration developed can barely reach 3.0 g (Bosco 1992). This means stimulating the muscles for 2 min per week for a total amount in one year of 108 minutes. In a few words, vibrations can stimulate the biological system of athletes in the same way as strength training or explosive training and this stimulation can be applied in a much shorter period of time as compared to the time needed to perform traditional training sessions. It opens a new window in sports science and gives coaches and scientists new possibilities for studying and enhancing human performance. |
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It has been demonstrated that vibration drives alpha-motoneurons via the la loop producing force without decreasing motor drive (Rothmuller and Cafarelli, 1995). Although it has been suggested that the vibration reflex, like the tendon jerk reflex, operates predominantly or exclusively on alpha motoneurons and does not utilise the same cortically originating efferent path- ways as are used when performing voluntary contractions (Burke et al. 1976). It cannot be excluded that vibration treatments can also affect voluntary movements. These suggestions are supported by the present findings. In fact the EMG recorded in the biceps brachii of the experimental group in the study conducted on boxers showed a significant enhancement (P<0.001) of the neural activity during the treatment period, as compared to normal conditions (Bosco et al. 1999a). 
Thus it is likely that both neural adaptation and the length of the stimulus seem to play an important role in the improvement of muscle performances (e.g. Bosco, 1985). During the VT utilised for the research conducted on the boxers, the elbow flexors were stimulated for a total length of time of 300 seconds. The duration of the treatment was similar to that required to perform an elbow flexion for 600 repetitions with a load similar to 50/0 of the subject's body mass. Such an amount of repetitions would generally otherwise be distributed over 3 sessions a week with 50 repetitions per time, taking one month to complete. The large initial increases noted in muscle strength observed during the earlier weeks of intense strength training can be explained through increases in maximal neural activation (e.g. Moritani and De Vries, 1979). To explain how the increased neural output may occur is not as simple as how to explain the intrinsic mechanism of neural adaptation. Furthermore, a net excitation of the prime mover motoneurons could result from increased excitatory input, reduced inhibitory input or both (e.g. Sale, 1988). 