A. Prochazka

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Hoffmann (H) reflexes were elicited from the soleus (SOL) muscle while subjects walked on a treadmill and on a narrow beam (3.5 cm wide, raised 34 cm from the floor). The speed of walking on the treadmill was selected for each subject to match the background activation level of their SOL muscle during beam walking. The normal reciprocal activation pattern(More)
It is known that the springlike properties of muscles provide automatic load compensation during weight bearing. How crucial is sensory control of the motor output given these basic properties of the locomotor system? To address this question, a neuromuscular model was used to test two hypotheses. (1) Stretch reflexes are too weak and too delayed to(More)
If an obstacle impedes the forward swing of a cat's foot, the animal responds by rapidly lifting the foot over the obstacle. In freely moving cats, the electrical activity of hindlimb flexors and extensors was recorded during such reactions elicited both mechanically and electrically. The sequencing of muscle activity was more complex and longer in duration(More)
BACKGROUND Detrusor-sphincter dyssynergia is a condition in which reflexive contractions of the external urethral sphincter occur during bladder contractions, preventing the expulsion of urine. High-frequency stimulation (kHz range) has been shown to elicit a fast-acting and reversible block of action potential propagation in peripheral nerves, which may be(More)
1. Implanted semimicroelectrodes were used to record single afferent fiber discharges from L7 dorsal roots during unrestrained walking in the conscious cat. 2. A series of tests were used to identify an afferent during a short period of anesthesia following each recording session. The majority of afferents were from muscle spindle primary endings in(More)
Are the words reflex and voluntary useful scientific concepts, or are they prescientific terms that should be discarded? Physiologists use these words routinely in their publications, in laboratory experiments and, indeed, like most lay people, in their daily lives. The tacit assumption is that we all know, more or less, what they mean. However, the issue(More)
1. Electrical activity and length of ankle muscles were recorded by telemetry during free fall and landing in cats. 2. After foot contact, there was a delay in onset of stretch of ankle extensors of between 8 and 11 ms. High-speed cinematography showed the delay to be associated with rapid initial dorsiflexion of the toes. 3. Electromyograms (e.m.g.) from(More)
1. Discharge of muscle spindles during voluntary movement Recent recordings from afferents in awake animals have re-emphasized the function of spindle endings as stretch receptors. The available evidence suggests that, in voluntary movements involving muscle velocities above 0.2 RL sec-1 the modulation of firing rate of both primary and secondary endings is(More)
  • A. Prochazka
  • Canadian journal of physiology and pharmacology
  • 1986
In the last decade, a number of laboratories have accumulated data on the firing of single afferent fibres from muscle and skin during movement in awake cats, monkeys and human subjects. While there is general agreement on the firing behaviour of skin afferents and tendon organ (Ib) afferents during movement, there remains a significant divergence of(More)
The management of urinary tract dysfunction is crucial for the health and well-being of people with spinal cord injury. Devices, specifically catheters, play an important role in the daily regime of bladder management for most people with spinal cord injury. However, the high incidence of complications associated with the use of catheters, and the fact that(More)