Helmut Seidel

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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 (I1 = 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,(More)
The great variability of the flexion of the cervical spine renders an exact description of the control of various positions difficult. A method was developed enabling a precise control of positioning the cervical spine and head in the sagittal plane. In three repeated measurements the mean values of the position of external anatomical landmarks and(More)
The effects of muscle spindle activation on different postural muscles were examined in eight volunteers, using a force platform technique. Small electrical vibrators were placed symmetrically over the muscles concerned and the effects of vibration frequencies of 20, 40, 60, 80 and 100 Hz were studied at a constant amplitude of 0.4 mm (peak-to-peak).(More)
The aim of the study was to obtain information on changes in surface electromyograms from the lumbar erector spinae muscles during fatiguing isometric contractions. Four male subjects held different target extension forces to fatique in a prone position under carefully controlled biomechanical conditions. Standard deviations of the distribution of EMG(More)
The aim of this experimental study was to estimate the strain in the lumbar spine due to whole-body vibration (WBV). Four male subjects were exposed to vertical sinusoidal WBV with frequencies ranging from 1 to 15 Hz at two intensities (I1 = 1.5 ms-2 rms; I2 = 3.0 ms-2 rms). The compressive forces acting on the disc L3-4 during the extreme values of(More)
Back problems are very common and contribute to discomfort and days off work. Some back disorders are attributed to inappropriate loading of the spine that can be combined with other influential factors such a body posture, whole-body vibration and shock. Many models have been developed to predict the forces in the spine associated with vibration and shock.(More)
A conceptual framework provides the possibility to identify factors determining the effects of whole-body vibration (WBV) on the spine and the internal stress-strain relationships. Epidemiological studies were critically evaluated with respect to their significance for the derivation of quantitative exposure-effect relationships. The approach of deriving(More)
This study was carried out in order: (1) to examine the effects of isolated and combined prolonged exposures to noise and whole-body vibration on hearing, vision and subjectively experienced strain, and (2) to check the combined effects with repeated exposures. Six male subjects were exposed twice to noise (N) at 92 dBA, whole-body vibration (V) in the(More)