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R Herman

Publications and source records attributed to R Herman.

At least 91 records · Page 5Linked to original sources
PubMed1976

EMG patterns and forces developed during step-down.

These experiments describe electromyographic activity and forces developed during step-down from several heights. The external environment of the experimental subjects was varied by blindfold or Achilles' tendon vibration during descent. EMG activity of the step-down limb, vertical force of impact and knee angle were measured. The results show that the triceps surae muscle contracts prior to the time of impact of the foot with the substrate if information about the step height is supplied to the subject and if the sensory system is not disturbed by vibration. In the presence of vibration or if the step height is unknown, the triceps surae does not contract prior to foot contact. This produces a large force transient which must be absorbed by the skeletal structure, rather than being damped by a lengthening contraction of the triceps surae. The data suggest that the forces developed during ordinary step-down may be the cause of bone and injury in people with impaired vision or in patients with damaged nervous systems who exhibit large responses to vibration.

Biomechanical Phenomena↗
PubMed1975

Inhibition of electromyographic activity in human triceps surae muscles during sinusoidal rotation of the foot.

Torque and electromyographic (EMG) responses to sinusoidal rotations of the foot were measured. The frequency range of the movements was 0.5 Hz to 15 Hz at amplitudes ranging between 1 and 10 degrees. At frequencies above 7 Hz, the EMG activity did not follow individual foot rotation cycles. The EMG activity was inhibited whenever the peak torque was large with respect to the first cycle peak torque. Dantrolene sodium reduced the torque developed in triceps surae, allowing the EMG activity to follow individual stretch cycles. As the drug was metabolized, the EMG activity returned to the character seen in the pre-drug control--that is, inhibition on alternate stretch cycles. It is concluded that the EMG inhibition phenomenon can be attributed in part to force receptors in muscle but that these receptors are not the sole contributors to the inhibition.

Adult↗