Depression of Hoffmann Reflexes Following Voluntary Contraction and Implications for Proprioceptive Neuromuscular Facilitation Therapy

Abstract

Postcontraction depression of Hoffmann-reflex (H-reflex) amplitudes was examined to study the rationale underlying proprioceptive neuromuscular facilitation relaxation techniques. The time course of H-reflex amplitude depression was used to assess postcontraction changes in motoneuron reflex excitability. Sixteen healthy female subjects performed voluntary isometric plantar-flexion contractions (65%-75% of maximal voluntary contraction) in a prone position. H-reflex stimulation began at a postcontraction delay of 0.05, 0.1, 0.5, 1, or 5 seconds and continued every 10 seconds for 1 minute. Reflexes were depressed (mean = 67% decrease) by 0.05 second postcontraction, reached maximal depression (mean = 83.3% decrease) from 0.1 to 1 second postcontraction, recovered to 70% of control amplitudes (mean = 30% decrease) by 5 seconds postcontraction, and reached 90% control amplitudes (mean = 10% decrease) by 10.05 seconds postcontraction. The results indicate that proprioceptive neuromuscular facilitation techniques (eg, hold-relax) purported to produce a phase of relaxation following voluntary contraction do appear to produce a strong, but brief, neuromuscular inhibition that may be clinically useful for applying stretch.

Joint angle affects volitional and magnetically-evoked neuromuscular performance differentially

“…Another auditory signal was given to the participant after 2-3 seconds of MVA to cue neuromuscular relaxation. The three intra-trial MVA replicates were 165 each separated by at least 10-seconds to enable neuromuscular recovery [Moore and Kukulka, 1991].…”

Effects of acute fatigue on the volitional and magnetically-evoked electromechanical delay of the knee flexors in males and females

“…Another auditory signal was given to the participant after 2 -3 seconds of MVMA to cue neuromuscular relaxation. Intra-trial MVMA replicates were each separated by at least 10 seconds to enable neuromuscular recovery (Moore and Kukulka 1991).…”

“…The latter instances were associated with limitations of the technological capability of the stimulation system. Sequential stimulations throughout the experimental period were separated by at least 10 seconds to ensure neuromuscular recovery (Moore and Kukulka 1991).…”

Contraction history produces task‐specific variations in spinal excitability in healthy human soleus muscle

“…6 We interpret these results to mean that the intensity and duration of isometric contractions do not contribute to PAP. We speculate that, rather than the characteristics of the isometric contraction, the nature of muscle contraction modulates PAP.…”

“…After a voluntary isometric contraction, the H-reflex is depressed for 8-50 s. 2,[4][5][6] (Table 1). This reduction in H-reflex amplitude is known as PAD, which is presumably due to neurotransmitter depletion at the Ia terminals.…”