The Effect of Short-term Muscle Vibration on Knee Joint Torque and Muscle Firing Patterns during a Maximal Voluntary Isometric Contraction (original) (raw)
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Journal of sports science & medicine, 2004
At present there appears to be a need for research conducted on the effects of vibration on the contractile ability of skeletal muscle tissue. The aim of this study was to address this issue by examining the effects of a superimposed muscle/tendon vibration at 50.42±1.16 Hz (acceleration 13.24 ± 0.18ms(-2): displacement ≈5mm) on muscular activation and maximal isometric contraction. Sixteen participants with a mean age, body mass, and height of 22 ± 4.4 years, 73.2 ± 11.7 kg and 173.1 ± 9.7 cms, respectively, were recruited for this study. Electromyography and accelerometry from the rectus femoris, and maximal isometric force data characteristics were collected from the dominant limb under conditions of vibration, and no-vibration. A superimposed 50 Hz vibration was used during the contraction phase for the maximal isometric leg extension for the condition of vibration. A one-way ANOVA revealed no significant (p > 0.05) differences between the vibration and no-vibration condition...
Motor performance changes induced by muscle vibration
European Journal of Applied Physiology, 2006
The possibility that mechanical stimulation of selected muscles can act directly on the nervous system inducing persistent changes of motor performances was explored. On the basis of literature, stimulating parameters were chosen to stimulate the central nervous system and to avoid muscle Wbre injuries. A sinusoidal mechanical vibration was applied, for three consecutive days, on the quadriceps muscle in seven subjects that performed a muscular contraction (VC). The same stimulation paradigm was applied on seven subjects in relaxed muscle condition (VR) and seven subjects were not treated at all (NV). Two sessions (PRE and POST) of isometric and isotonic tests were performed separated for 21 days, in all studied groups 7 days before and 15 days after stimulation, whilst an isokinetic test was performed on VC only. In the isometric test, the time of force development showed a signiWcant decrease only in VC (POST vs PRE mean 27.8%, P < 0.05). In the isotonic test, the subjects' had to perform a fatiguing leg extension against a load. In this condition, the fatigue resistance increased greatly in VC (mean 40.3%, P < 0.001), increased slightly in VR and there was no diVerence in NV. In Isokinetic test, at several angular velocities, sig-niWcantly less time was required to reach the force peak (mean 20.2% P < 0.05). The Wndings could be ascribed to plastic changes in proprioceptive processing, leading to an improvement in knee joint control. Such action delineates a new tool in sports training and in motor rehabilitation.
Effects of vibration on maximal isometric muscle contraction at different joint angles
Isokinetics and Exercise Science, 2006
The purpose of the present study was to determine the effects vibration, applied with different frequencies at different joint angles, on maximal isometric muscle contraction. Forty male volunteers were randomly and equally assigned to one of the four different vibration stimulation groups as 6 Hz, 12 Hz, 24 Hz and 48 Hz. Subjects performed three consecutive isometric maximal voluntary contractions (MVC) with and without vibration for six seconds with one-minute interval at 90, 120 and 150 degrees of elbow angles in random order. During MVC with vibration tests vibration was applied to upper arm 10 seconds before the contraction begins and continued throughout the MVC. According to results of 4 × 3 × 2 ANOVA with repeated measures, significant joint angle effect (p < 0.001), contraction type effect (p < 0.001) and significant frequency × contraction type interaction (p < 0.001) was found. It can be concluded that vibration stimulation resulted in increased isometric MVC. Results also suggested that stimulating muscles with 6, 12 and 24 Hz of vibration resulted in increased isometric MVC, 48 Hz of vibration on the other hand resulted in decreased isometric MVC. In addition, the length of the contracting muscle did not affect the vibration load that was applied with different frequencies.
Scientific Reports, 2022
The aim of this study is to characterise the transient mechanical response and the neuromuscular activation of lower limb muscles in subjects undergoing Whole Body Vibration (WBV) at different frequencies while holding two static postures, with focus on muscles involved in shaping postural responses. Twenty-five participants underwent WBV at 15, 20, 25 and 30 Hz while in hack squat or on fore feet. Surface electromyography and soft tissue accelerations were collected from Gastrocnemius Lateralis (GL), Soleus (SOL) and Tibialis Anterior (TA) muscles. Estimated displacement at muscle bellies revealed a pattern never highlighted before that differed across frequencies and postures (p < 0.001). After stimulation starts, muscle oscillation peaks, drops and further stabilises, suggesting the occurrence of a neuromuscular activation to reduce the vibration-induced oscillation. The oscillation attenuation at the SOL muscle correlated with its increased activation (rho = 0.29, p < 0.001). Furthermore, only specific WBV settings led to a significant increase in muscle contraction: WBV-induced activation of SOL and GL was maximal in fore-feet (p < 0.05) and in response to higher frequencies (30 Hz vs 15 Hz, p < 0.001). The analysis of the mechanical dynamics of lower leg muscles highlights a resonant response to WBVs, that for the SOL correlates to the increased muscle activation. Despite differing across frequencies and postures, this resonant behaviour seems to discourage the use of dynamic exercises on vibrating platforms. As for the most efficient WBV combination, calf muscle response to WBVs is maximised if those muscles are already pre-contracted and the stimulation frequencies are in the 25-30 Hz range. Whole Body Vibration (WBV) refers to the use of mechanical stimulation, in the form of vibratory oscillations extended to the whole body, to elicit neuromuscular responses in multiple muscle groups 1. This approach has become increasingly popular as it evokes large muscle responses and, more importantly, it elicits muscle activity through physiological pathways, improving the overall motor performance while enhancing strength and flexibility 2-7. Although the effective mechanisms behind neuromuscular outcomes in WBV have been debated for long time 1,2,8 , those that go under the names of tonic vibration reflex (TVR) and muscle tuning are the most accredited for. It is well known that, when vibrations are applied directly to tendons or muscle bellies (i.e., focal vibrations), fibres length changes activating a reflex increased motor-unit (MU) firing rates 9,10 , phased-locked specifically to the vibratory cycle-namely TVR 9,11,12. WBV stimulation is characterised by a much lower frequency range (15 to 45 Hz) than typical focal stimulations (> 100 Hz) and vibrations are generally delivered to the lower limbs via the use of platforms on which subjects stand: being a mechanical stimulus, vibrations are transferred through the kinematic chain determined by the body posture 13-15. To confirm the occurrence of the TVR mechanism
The effects of a 28-Hz vibration on arm muscle activity during isometric exercise
Medicine & Science in Sports & Exercise, 2009
MISCHI, M., and M. CARDINALE. The Effects of a 28-Hz Vibration on Arm Muscle Activity during Isometric Exercise. Med. Sci. Sports Exerc., Vol. 41, No. 3, pp. 645-652, 2009. Purpose: The aim of this study was to evaluate activation and coactivation of biceps and triceps muscles during isometric exercise performed with and without superimposing a vibration stimulation. Methods: Twelve healthy volunteers (age = 22.7 T 2.6 yr) participated in this study. The subjects performed five trials of isometric elbow flexion and five trials of elbow extension with increasing levels of force in two conditions: vibration (V) and normal loading (C). V stimulation was characterized by a frequency of 28 Hz. Surface EMG activity of biceps and triceps muscles was simultaneously measured by bipolar surface electromyography and assessed by the estimation of the root mean square (RMS) of the electrical recordings over a fixed 5-s interval. Frequency analysis was adopted to estimate the RMS related to muscle activation and to exclude the harmonics generated by movement artifacts due to V. Results: The analysis of the recordings revealed a significant EMG RMS increase when V was applied. On average, the EMG RMS of biceps and triceps during elbow flexion was, respectively, 26.1% (P G 0.05) and 18.2% (P = 0.15) higher than C. During elbow extension, the EMG RMS of biceps and triceps was 77.2% and 45.2% (P G 0.05) higher than C, respectively. The coactivation was assessed as the ratio between the activation of antagonist and agonist muscles during arm flexion and extension tasks. The results revealed an increase of coactivation during V exercise, especially for lighter loads. Conclusion: This study shows that V exercise at 28 Hz produces an increase of the activation and the coactivation of biceps and triceps. This exercise modality seems therefore suitable for various applications.
Acute Whole-Body Vibration does not Facilitate Peak Torque and Stretch Reflex in Healthy Adults
Journal of sports science & medicine, 2014
The acute effect of whole-body vibration (WBV) training may enhance muscular performance via neural potentiation of the stretch reflex. The purpose of this study was to investigate if acute WBV exposure affects the stretch induced knee jerk reflex [onset latency and electromechanical delay (EMD)] and the isokinetic knee extensor peak torque performance. Twenty-two subjects were randomly assigned to the intervention or control group. The intervention group received WBV in a semi-squat position at 30° knee flexion with an amplitude of 0.69 mm, frequency of 45 Hz, and peak acceleration of 27.6 m/s(2) for 3 minutes. The control group underwent the same semii-squatting position statically without exposure of WBV. Two-way mixed repeated measures analysis of variance revealed no significant group effects differences on reflex latency of rectus femoris (RF) and vastus lateralis (VL; p = 0.934 and 0.935, respectively) EMD of RF and VL (p = 0.474 and 0.551, respectively) and peak torque produ...
Vibration parameters affecting vibration-induced reflex muscle activity
Somatosensory & Motor Research, 2017
Purpose: To determine vibration parameters affecting the amplitude of the reflex activity of soleus muscle during low-amplitude whole-body vibration (WBV). Materials and methods: This study was conducted on 19 participants. Vibration frequencies of 25, 30, 35, 40, 45, and 50 Hz were used. Surface electromyography, collision force between vibration platform and participant's heel measured using a force sensor, and acceleration measured using an accelerometer fixed to the vibration platform were simultaneously recorded. Results: The collision force was the main independent predictor of electromyographic amplitude. Conclusion: The essential parameter of vibration affecting the amplitude of the reflex muscle activity is the collision force.
The Effexts of Prior Antagonist Muscle Vibration on Performance of Rapid Movements
Journal of Electromyography and Kinesiology, 1998
The effects of prior vibration of the antagonist triceps muscle on the performance of rapid discrete elbow flexion movements were studied in healthy volunteers. The subjects performed 520 movements over five experimental sessions. The application of prior vibration resulted in a shift of the initial position, an undershoot of the final position in untrained subjects, and also in trained subjects if not applied during practice. On the contrary, no undershoot occurred in trained subjects when prior vibration was applied during practice. Improvement in movement performance, as judged by a decrease in variability of the final position, was less successful when vibration was applied during practice. It is supposed that the undershoots were due to prior vibration-induced alterations in proprioceptive messages and a consequent erroneous sense of the arm position. These effects seem to be overcome by practice, but also seem to interfere with learning-based movement improvement.
Adaptive response of the human skeletal muscle to vibration exposure
The aim of this study was to investigate the effects of whole-body vibrations (WBV) on the mechanical behaviour of human skeletal muscle. For this purpose, six female volleyball players at national level were recruited voluntarily. They were tested with maximal dynamic leg press exercise on a slide machine with extra loads of 70, 90, 110 and 130 kg. After the testing, one leg was randomly assigned to the control treatment (C) and the other to the experimental treatment (E) consisting of vibrations. The subjects were then retested at the end of the treatment using the leg press. Results showed remarkable and statistically signi®cant enhancement of the experimental treatment in average velocity (AV), average force (AF) and average power (AP) (P<0á05±0á005). Consequently, the velocity±force and power±force relationship shifted to the right after the treatment. In conclusion, it was af®rmed that the enhancement could be caused by neural factors, as athletes were well accustomed to the leg press exercise and the learning effect was minimized.