Summary
5 healthy males were exposed to vertical sinusoidal whole body vibration (WBV) at 5 frequencies (F1=0.315 Hz, F2=0.63 Hz, F3=1.25 Hz, F4=2.5 Hz, F5=5.0 Hz) and 2 intensities (11=1.2 ms−2 rms, F1-F5; I2=2.0 ms−2 rms, F2–F5). Erector spinae EMGs were derived at the levels of the first thoracic (T1) and third lumbar (L3) spinous processes, rectified and synchronously averaged, as were the accelerations of the seat and the head. WBV induced vibration-synchronous EMG activity (T1 and L3) which exceeded the activity without WBV during enhanced gravitation and decreased during lowered gravitation from F1 to F3. At F4 and F5, these phase relations changed drastically, thus suggesting a different trigger mechanism. The extreme average EMG-amplitudes remained nearly constant at F1 to F3 and increased at higher frequencies. Maximum EMG activity was higher at I2 than at I1. WBV from F1 to F3 is supposed to cause tonic muscular activity triggered by the otoliths; at higher frequencies, stretch reflexes probably gain additional importance. The results hint at an increasing sensory conflict with decreasing frequency of WBV and are interpreted within the theoretical framework of different modes of motor control. Relations between transmissibility and muscle activity suggest the usefulness of including time-variant spring-characteristics into biomechanical models.
Similar content being viewed by others
References
Blüthner R, Hinz B, Seidel H (1986) Zur Möglichkeit einer Abschätzung der Wirbelsäulenbeanspruchung durch Ganzkörpervibration unter experimentellen Bedingungen. Z Ges Hyg 32:111–113
Droulez J, Berthoz A, Vidal PP (1985) Use and limits of visual vestibular interaction in the control of posture. Are there two modes of sensorimotor control? In: Igarashi M, Black FO (eds) Vestibular and visual control on posture and locomotor equilibrium. 7th Int. Symp. Int. Soc. Posturography, Houston, Texas 1983. Karger, Basel, pp 14–21
Hinz B, Seidel H, Bluethner R (1985) On the effects of wholebody vibration on the spine — the significance of the human biodynamics. In: Frolov KV (ed) Proceedings of the second international CISM-IFToMM Symposium. Moscow, pp 56–60
Kohl RL (1983) Sensory conflict theory of space motion sickness: an anatomical location for the neuroconflict. Aviat Space Environ Med 54:464–465
Lacour M, Vidal PP, Xerri C (1981) Early directional influence of visual motion cues on postural control in the falling monkey. Ann NY Acad Sci 374:403–411
Melvill Jones G, Watt DG (1971) Muscular control of landing from unexpected falls in man. J Physiol 219:729–737
O'Hanlon JF, McCauly ME (1974) Motion sickness incidence as a function of the frequency and acceleration of vertical sinusoidal motion. Aerospace Med 45:366–369
Seidel H, Beyer H, Bluethner R, Braeuer D, Hinz B, Menzel G, Weissmueller A (1985) Electromyography in back research — assessment of static and dynamic conditions. In: Perren SM and Schneider E (eds) Biomechanics: Current Interdisciplinary Research. Martinus Nijhoff Publishers, Dordrecht, Boston, Lancester, pp 611–616
Seidel H, Bluethner R, Hinz B (1986) Effects of sinusoidal whole-body vibration on the lumbar spine: the stress-strain relationship. Int Arch Occup Environ Health 57:207–223
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Seidel, H. Myoelectric reactions to ultra-low frequency and low-frequency whole body vibration. Europ. J. Appl. Physiol. 57, 558–562 (1988). https://doi.org/10.1007/BF00418462
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00418462