Sympathetic outflow enhances the stretch reflex response in the relaxed soleus muscle in humans

2005 ◽  
Vol 98 (4) ◽  
pp. 1366-1370 ◽  
Author(s):  
Nis Hjortskov ◽  
Jørgen Skotte ◽  
Christian Hye-Knudsen ◽  
Nils Fallentin
Keyword(s):  
Soleus Muscle ◽  
Stretch Reflex ◽  
Mental Arithmetic ◽  
Muscle Spindles ◽  
Short Latency ◽  
Reflex Response ◽  
Sympathetic Outflow ◽  
Direct Influence ◽  
Handgrip Exercise ◽  
Sympathetic Nervous

Animal experiments suggest that an increase in sympathetic outflow can depress muscle spindle sensitivity and thus modulate the stretch reflex response. The results are, however, controversial, and human studies have failed to demonstrate a direct influence of the sympathetic nervous system on the sensitivity of muscle spindles. We studied the effect of increased sympathetic outflow on the short-latency stretch reflex in the soleus muscle evoked by tapping the Achilles tendon. Nine subjects performed three maneuvers causing a sustained activation of sympathetic outflow to the leg: 3 min of static handgrip exercise at 30% of maximal voluntary contraction, followed by 3 min of posthandgrip ischemia, and finally during a 3-min mental arithmetic task. Electromyography was measured from the soleus muscle with bipolar surface electrodes during the Achilles tendon tapping, and beat-to-beat changes in heart rate and mean arterial blood pressure were monitored continuously. Mean arterial pressure was significantly elevated during all three maneuvers, whereas heart rate was significantly elevated during static handgrip exercise and mental arithmetic but not during posthandgrip ischemia. The peak-to-peak amplitude of the short-latency stretch reflex was significantly increased during mental arithmetic ( P < 0.05), static handgrip exercise ( P < 0.001), and posthandgrip ischemia ( P < 0.005). When expressed in percent change from rest, the mean peak-to-peak amplitude increased by 111 (SD 100)% during mental arithmetic, by 160 (SD 103)% during static handgrip exercise, and by 90 (SD 67)% during posthandgrip ischemia. The study clearly indicates a facilitation of the short-latency stretch reflex during increased sympathetic outflow. We note that the enhanced stretch reflex responses observed in relaxed muscles in the absence of skeletomotor activity support the idea that the sympathetic nervous system can exert a direct influence on the human muscle spindles.

Statistical Considerations When Assessing Short Latency Stretch Reflexes in the Human Soleus Muscle

Motor Control ◽  
2015 ◽  
Vol 19 (4) ◽  
pp. 253-270 ◽  
Author(s):  
Asger Roer Pedersen ◽  
Peter William Stubbs ◽  
Jørgen Feldbæk Nielsen
Keyword(s):  
Ankle Joint ◽  
Soleus Muscle ◽  
Stretch Reflex ◽  
Short Latency ◽  
Response Magnitude ◽  
Variance Heterogeneity ◽  
Stretch Reflexes ◽  
Response Characteristics ◽  
Normally Distributed

The aim was to investigate trial-by-trial response characteristics in the short-latency stretch reflex (SSR). Fourteen dorsiflexion stretches were applied to the ankle joint with a precontracted soleus muscle on 2 days. The magnitude and variability of trial-by-trial responses of the SSR were assessed. The SSR was log-normally distributed and variance heterogeneous between subjects. For some subjects, the magnitude and variance differed between days and stretches. As velocity increased, variance heterogeneity tended to decrease and response magnitude increased. The current study demonstrates the need to assess trial-by-trial response characteristics and not averaged curves. Moreover, it provides an analysis of SSR characteristics accounting for log-normally distributed and variance heterogeneous trial-by-trial responses.

Damping Actions of the Neuromuscular System With Inertial Loads: Soleus Muscle of the Decerebrate Cat

2000 ◽  
Vol 83 (2) ◽  
pp. 652-658 ◽  
Author(s):  
David C. Lin ◽  
W. Zev Rymer
Keyword(s):  
Energy Dissipation ◽  
Linear System ◽  
Soleus Muscle ◽  
Stretch Reflex ◽  
Directional Asymmetry ◽  
Reflex Response ◽  
Neuromuscular System ◽  
Damping Properties ◽  
Kinetic Measurements ◽  
Decerebrate Cat

A transient perturbation applied to a limb held in a given posture can induce oscillations. To restore the initial posture, the neuromuscular system must provide damping, which is the dissipation of the mechanical energy imparted by such a perturbation. Despite their importance, damping properties of the neuromuscular system have been poorly characterized. Accordingly, this paper describes the damping characteristics of the neuromuscular system interacting with inertial loads. To quantitatively examine damping, we coupled simulated inertial loads to surgically isolated, reflexively active soleus muscles in decerebrate cats. A simulated force impulse was applied to the load, causing a muscle stretch, which elicited a reflex response. The resulting deviation from the initial position gave rise to oscillations, which decayed progressively. Damping provided by the neuromuscular system was then calculated from the load kinetics. To help interpret our experimental results, we compared our kinetic measurements with those of an analogous linear viscoelastic system and found that the experimental damping properties differed in two respects. First, the amount of damping was greater for large oscillation amplitudes than for small (damping is independent of amplitude in a linear system). Second, plots of force against length during the induced movements showed that damping was greater for shortening than lengthening movements, reflecting greater effective viscosity during shortening. This again is different from the behavior of a linear system, in which damping effects would be symmetrical. This asymmetric and nonlinear damping behavior appears to be related to both the intrinsic nonlinear mechanical properties of the soleus muscle and to stretch reflex properties. The muscle nonlinearities include a change in muscle force-generating capacity induced by forced lengthening, akin to muscle yield, and the nonlinear force-velocity property of muscle, which is different for lengthening versus shortening. Stretch reflex responses are also known to be asymmetric and amplitude dependent. The finding that damping is greater for larger amplitude motion represents a form of automatic gain adjustment to a larger perturbation. In contrast, because of reduced damping at small amplitudes, smaller oscillations would tend to persist, perhaps contributing to normal or “physiological” tremor. This lack of damping for small amplitudes may represent an acceptable compromise for postural regulation in that there is substantial damping for larger movements, where energy dissipation is more critical. Finally, the directional asymmetry in energy dissipation provided by muscle and reflex properties must be reflected in the neural mechanisms for a stable posture.

Voluntary and reflexive recruitment of flexor carpi radialis motor units in humans

1985 ◽  
Vol 53 (5) ◽  
pp. 1194-1200 ◽  
Author(s):  
B. Calancie ◽  
P. Bawa
Keyword(s):  
Motor Unit ◽  
Stretch Reflex ◽  
Latency Period ◽  
Motor Units ◽  
Short Latency ◽  
Reflex Response ◽  
Recruitment Threshold ◽  
Flexor Carpi Radialis ◽  
Single Motor Units ◽  
Long Latency

The order of recruitment of flexor carpi radialis (FCR) motor units was studied during voluntary and reflexive activation of the motoneuron pool for two adult subjects. During slow "voluntary" activation, the recruitment threshold for tonic motoneuron firing was determined, and then the twitch profile of the motor unit was computed by the spike-triggered averaging technique. A positive correlation (r = 0.79 and 0.68 for the two subjects, respectively) between recruitment threshold and twitch amplitude implies that recruitment of FCR motoneurons during slow ramp isometric contractions proceeds in order of increasing size. The accompanying paper describes the behavior of single motor units during the short- and long-latency periods of the stretch reflex. When the effects of sufficient voluntary facilitation (preload) combined with a sufficiently large torque step were just adequate to cause a motor unit to fire during the stretch reflex, its response was virtually always confined to the long-latency period. In addition, the first unit to begin responding to muscle stretch always had the lowest voluntary recruitment threshold relative to other units "visible" at that recording site. By making this unit tonic, the reflex response to the same load increased substantially during the short-latency reflex period, while a second unit increased its reflex response probability during the long-latency period. Thus the voluntary recruitment order of two or more motor units is preserved during the stretch reflex, and is in fact maintained within first the long-latency and then short-latency components of this reflex.

Does whole-body vibration acutely improve power performance via increased short latency stretch reflex response?

2013 ◽  
Vol 16 (4) ◽  
pp. 360-364 ◽  
Author(s):  
Igor Alexandre Fernandes ◽  
Gregory Kawchuk ◽  
Yagesh Bhambhani ◽  
Paulo Sergio Chagas Gomes
Keyword(s):  
Stretch Reflex ◽  
Whole Body Vibration ◽  
Short Latency ◽  
Reflex Response ◽  
Whole Body ◽  
Power Performance ◽  
Body Vibration

scholarly journals Developmental Changes in Hemodynamic Responses and Cardiovagal Modulation during Isometric Handgrip Exercise

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Styliani Goulopoulou ◽  
Bo Fernhall ◽  
Jill A. Kanaley
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Isometric Contraction ◽  
Pressor Response ◽  
Reflex Response ◽  
Group Differences ◽  
Handgrip Exercise ◽  
Isometric Handgrip ◽  
Isometric Handgrip Exercise ◽  
Pressor Reflex

The purpose of this study was to examine differences in pressor response and cardiovagal modulation during isometric handgrip exercise (IHG) between children and adults. Beat-to-beat heart rate (HR) and blood pressure were measured in 23 prepubertal children and 23 adults at baseline and during IHG. Cardiovagal modulation was quantified by analysis of HR variability. Mean arterial pressure responses to IHG were greater in adults compared to children (P<.05) whereas there were no group differences in HR responses (P>.05). Children had a greater reduction in cardiovagal modulation in response to IHG compared to adults (P<.05). Changes in mean arterial pressure during IHG were correlated with baseline cardiovagal modulation and force produced during isometric contraction (P<.05). In conclusion, differences in pressor reflex response between children and adults cannot be solely explained by differences in autonomic modulation and appear to be associated with factors contributing to the force produced during isometric contraction.

Enhanced stretch reflex excitability of the soleus muscle in experienced swimmers

2008 ◽  
Vol 105 (2) ◽  
pp. 199-205 ◽  
Author(s):  
Tetsuya Ogawa ◽  
Gee Hee Kim ◽  
Hirofumi Sekiguchi ◽  
Masami Akai ◽  
Shuji Suzuki ◽  
...  
Keyword(s):  
Soleus Muscle ◽  
Stretch Reflex ◽  
Reflex Excitability

QUANTIFIED DEEP TENDON REFLEX DEVICE, SECOND GENERATION

2008 ◽  
Vol 08 (01) ◽  
pp. 75-85 ◽  
Author(s):  
ROBERT LEMOYNE ◽  
FOAD DABIRI ◽  
ROOZBEH JAFARI
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Stretch Reflex ◽  
Evaluation System ◽  
Deep Tendon Reflex ◽  
Reflex Response ◽  
Fundamental Aspect ◽  
Maximum Acceleration ◽  
Mems Accelerometer ◽  
Tendon Reflex

The deep tendon reflex is a fundamental aspect of neurological examinations. The severity of and degree of recovery from a traumatic brain injury can be assessed by the myotatic stretch reflex. A hyperactive reflex response is correlated with spasticity, which can also be correlated with the degree of damage to the supraspinal input, in essence assessing the severity of traumatic brain injury. The myotatic stretch reflex is clinically evaluated by the National Institute of Neurological Disorders and Stroke (NINDS) reflex scale (0–4); however, this scale lacks temporal data and may also vary in interpretation. The solution is a fully quantified evaluation system of the myotatic stretch reflex, whereby a patellar hammer's force input is based on original potential energy and a microelectromechanical system (MEMS) accelerometer quantifies the output. The MEMS accelerometer is attached to a set anchor point near the ankle. The reflex amplitude is based on the maximum acceleration of the reflex response. The quantified data collected from MEMS accelerometers are transmitted by a portable computer (i.e. a Pocket PC). This paper describes a device that quantitatively evaluates the reflex response using accelerometers and that demonstrates precision for reproducibility.

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