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The possibility of causing instability in the stretch reflex has been examined in three different human muscles: biceps, first dorsal interosseous (FDI) of the hand and digastric. Tremor recorded as fluctuation of isometric force was compared with that occurring during contraction against a spring load. The spring compliance was selected to make the natural(More)
1. A population of 269 gastrocnemius muscle spindle afferents have been studied in anaesthetized cats for the effects of succinylcholine (SCh) on their response to ramp and hold stretches repeated every 6 s. The effectiveness and reliability of the SCh test was improved by prior stimulation of the muscle at 10 Hz for 30 s to increase the blood flow. 2.(More)
1. The effects of the muscle-depolarizing drug succinylcholine (SCh) on the stretch responses of jaw-closer muscle spindle afferents were studied in the anaesthetized cat. Using ramp and hold stretches repeated every 6 s the basic measurements made were: initial frequency (IF), peak frequency (PF) and static index (SI), the frequency 0.5 s after the end of(More)
Simultaneous recordings were made from gamma (gamma) motor axons and from muscle spindle afferents of the medial gastrocnemius (MG) muscle during locomotion in decerebrate cats. The gamma-neurons were identified as static or dynamic (gammas or gammad) by correlating their behaviour during midbrain stimulation with changes in muscle spindle afferent(More)
Comparisons were made between the results of testing muscle spindle primary afferents with low-frequency, large-amplitude sine waves of muscle stretch and with repeating ramp-and-hold stretches. Three different situations were explored, namely, activation with succinylcholine (SCh), generation of various fusimotor outflow patterns by brainstem stimulation(More)
In locomotion, the flexor muscles of the leg are mainly concerned with the relatively constant task of raising the foot, whereas the extensors have the more variable task of support and propulsion at different speeds. This suggests that the way in which the fusimotor system works may differ between the two muscle groups. Observations previously made of the(More)
Recordings have been made from 127 single muscle spindle afferents from the longissimus lumborum muscles of anaesthetized cats. They have been characterized by their responses to passive muscle stretch and the effects of succinylcholine (SCh) and by their sensitivity to vibration. The use of SCh permitted the assessment for each afferent of the influence of(More)
The study of the patterns of gamma-motor activity which accompany natural contractions has been long and difficult, and has not as yet led to general agreement. In this review we have simplified matters by considering the case of locomotion in the cat only, and we have avoided discussion of the various hypotheses which have been advanced to provide general(More)
1. Recordings have been made from multiple single muscle spindle afferents from medial gastrocnemius (MG) and tibialis anterior (TA) muscles of one hindlimb in decerebrate cats, together with ankle rotation and EMG signals, during treadmill locomotion. Whilst the other three limbs walked freely, the experimental limb was denervated except for the nerves to(More)
This study examines the effect of 4 wk of high-intensity isometric resistance training on induced tremor in knee extensor muscles. Fourteen healthy volunteers were assigned to either the training group (n = 7) or the nontraining control group (n = 7). Induced tremor was assessed by measuring force fluctuations during anisometric contractions against spring(More)