Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Load receptors  (2)
  • 1990-1994  (2)
  • 1965-1969
  • 1
    ISSN: 1432-1106
    Keywords: Stance regulation ; Compensatory EMG responses ; Rotational/translational perturbations ; Load receptors ; Postural reflexes ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary According to recent observations, influence of body load has to be taken into account for the neuronal control of upright stance in addition to the systems known to be involved in this regulation (e.g. afferent input from vestibular canals, visual and muscle stretch receptors). The modulation of compensatory leg muscle electromyographic (EMG) responses observed during horizontal body posture indicates the existence of a receptor system which responds to loading of the body against the supporting platform. This receptor should be located within the extensor muscles because a compensatory EMG response and a loading effect on this response was only present following translational, but not rotational impulses. As the EMG responses were identical to those obtained during upright stance, it is argued that these load receptors activate postural reflexes. According to recent observations in the spinal cat, this afferent input probably arises from Golgi tendon organs and represents a newly discovered function of these receptors in the regulation of stance and gait.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1106
    Keywords: Stance regulation ; Adaptational processes ; Developmental aspects ; Load receptors ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recordings of electromyographic (EMG) leg muscle activity, head and joint movements and platform torque were taken in healthy subjects within three age groups (approximately 6, 10 and 〉22 years) standing upright upon a sinusoidally moving treadmill. The sinusoidal frequency was randomly changed between 0.5, 0.33 and 0.25 Hz, while the amplitude of the deflection was constant (±12 cm). During an adapted sinus, forward inclination of the body at the posterior turning point was associated with a slowly increasing tibialis anterior and decreasing gastrocnemius activity, while straightening of the body at the anterior turning point was associated with a sharply increasing gastrocnemius and decreasing tibialis anterior activity. The angle of forward inclination was greatest in the groups of children and was dependent upon both the sinus frequency and the child's height. The presumed programmed adjustment of the body inclination was such that the net effect of both inertial and gravitational forces acting on the body coincided approximately with the axis of the body at the posterior turning point. Changes of sinusoidal frequency were followed by compensatory responses, the amplitude of which depended upon the velocity of the body's displacement and the height of the subjects. In all three subject groups the response latencies were significantly shorter at the posterior turning point for the gastrocnemius response to a change from 0.5 to 0.25 Hz (105 ms for children and 119 ms for adults) than for the tibialis anterior response to a change from 0.25 to 0.5 Hz for which the values were 162 and 169 ms, respectively. This difference could be attributed to the forward inclination of the body at the posterior turning point which requires an earlier onset of compensatory extensor activity in order to maintain equilibrium. Adaptation to a new sinusoidal frequency occurred within 4 cycles following a change in sinus frequency. The phase shifts between treadmill position and the biomechanical and EMG signals that occurred during the adaptational process suggest that the position of the body's centre of gravity is the variable controlled by the programmed leg muscle activation. In young children the phase shifts during adaptation were absent, which may contribute to their greater instability. It is concluded that posture is continually adjusted in such a way that the resulting torque acting on the body during the treadmill movement becomes minimized. For this regulation load receptors in addition to the classical afferent impulses from visual, vestibular and muscle stretch receptors could play a major role.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...