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This Article Full Text Full Text (PDF) All Versions of this Article: 107/4/1051    most recent 00301.2009v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Leukel, C. Articles by Taube, W. PubMed PubMed Citation Articles by Leukel, C. Articles by Taube, W.

Short-term pressure induced suppression of the short-latency response: a new methodology for investigating stretch reflexes

¹Department of Sport Science, University of Freiburg, Freiburg, Germany; ; ²Department of Sport Science, University of Fribourg, Fribourg; and ; ³Spinal Cord Injury Centre, University Hospital Balgrist, Zürich, Switzerland; ; Department of ⁴Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark; and ; Department of ⁵Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark; ; ⁶Department of Training and Movement Science, University of Potsdam, Potsdam, Germany; and ; ⁷Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark

Submitted 20 March 2009 ; accepted in final form 12 August 2009

During experiments involving ischemic nerve block, we noticed that the short-latency response (SLR) of evoked stretches in m. soleus decreased immediately following inflation of a pneumatic cuff surrounding the lower leg. The present study aimed to investigate this short-term effect of pressure application in more detail. Fifty-eight healthy subjects were divided into seven protocols. Unilateral stretches were applied to the calf muscles to elicit a SLR, and bilateral stretches to evoke a subsequent medium-latency response (MLR). Furthermore, H-reflexes and sensory nerve action potentials (SNAPs) were recorded. Additionally, stretches were applied with different velocities and amplitudes. Finally, the SLR was investigated during hopping and in two protocols that modified the ability of the muscle-tendon complex distal to the cuff to stretch. All measurements were performed with deflated and inflated cuff. Results of the protocols were as follows: 1) inflation of the cuff reduced the SLR but not the MLR; 2) the H-reflex, the M-wave, and, 3) SNAPs of n. tibialis remained unchanged with deflated and inflated cuff; 4) the SLR was dependent on the stretch velocity with deflated and also inflated cuff; 5 and 6) the reduction of the SLR by the cuff was dependent on the elastic properties of the muscle-tendon complex distal to the cuff; and 7) the cuff reduced the SLR during hopping. The present results suggest that the cuff did not affect the reflex arc per se. It is proposed that inflation restricted stretch of the muscles underlying the cuff so that most of the length change occurred in the muscle-tendon complex distal to the cuff. As a consequence, the muscle spindles lying within the muscle may be less excited, resulting in a reduced SLR. Due to its applicability in functional tasks, the introduced method can be a useful tool to study afferent feedback in motor control.

Ia afferents; hopping; ischemia; medium latency response