Simon Brumagne

The Role of Paraspinal Muscle Spindles in Lumbosacral Position Sense in Individuals With and Without Low Back Pain

Study Design. A two-group experimental design with repeated measures on one factor was used. Objectives. To investigate the role of paraspinal muscle spindles in lumbosacral position sense in individuals with and without low back pain. Summary of Background Data. Proprioceptive deficits have been identified in patients with low back pain. The underlying mechanisms, however, are not well documented. Methods. Lumbosacral position sense was determined before, during, and after lumbar paraspinal muscle vibration in 23 young patients with low back pain and in 21 control subjects. Position sense was estimated by calculating the mean absolute error, constant error, and variable error between six criterion and reproduction sacral tilt angles. Results. Repositioning accuracy was significantly lower in the patient group than in healthy individuals (absolute error difference between groups = 2.7°, P < 0.0001). Multifidus muscle vibration induced a significant muscle-lengthening illusion that resulted in an undershooting of the target position in healthy individuals (constant error = −3.1°, P < 0.0001). Conversely, the position sense scores of the patient group did not display an increase in negative directional error but a significant improvement in position sense during muscle vibration (P < 0.05). No significant differences in absolute error were found between the first and last trial in the healthy individuals (P ≥ 0.05) and in the patient group (P > 0.05). Conclusions. Patients with low back pain have a less refined position sense than healthy individuals, possibly because of an altered paraspinal muscle spindle afference and central processing of this sensory input. Furthermore, muscle vibration can be an interesting expedient for improving proprioception and enhancing local muscle control.

Proprioceptive weighting changes in persons with low back pain and elderly persons during upright standing

The purpose of this study was to examine whether postural instability observed in persons with spinal pain and in elderly persons is due to changes in proprioception and postural control strategy. The upright posture of 20 young and 20 elderly persons, with and without spinal pain, was challenged by vibrating ankle muscles (i.e. tibialis anterior, triceps surae) or paraspinal muscles. Center of pressure displacement was recorded using a force plate. Persons with spinal pain were more sensitive to triceps surae vibration and less sensitive to paraspinal vibration than persons without spinal pain. Elderly persons were more sensitive to tibialis anterior vibration than young healthy persons. These results suggest that spinal pain and aging may lead to changes in postural control by refocusing proprioceptive sensitivity from the trunk to the ankles.

Coexistence of stability and mobility in postural control: evidence from postural compensation for respiration

This study evaluated the extent to which movement of the lower limbs and pelvis may compensate for the disturbance to posture that results from respiratory movement of the thorax and abdomen. Motion of the neck, pelvis, leg and centre of pressure (COP) were recorded with high resolution in conjunction with electromyographic activity (EMG) of flexor and extensor muscles of the trunk and hip. Respiration was measured from ribcage motion. Subjects breathed quietly, and with increased volume due to hypercapnoea (as a result of breathing with increased dead-space) and a voluntary increase in respiration. Additional recordings were made during apnoea. The relationship between respiration and other parameters was measured from the correlation between data in the frequency domain (i.e. coherence) and from time-locked averages triggered from respiration. In quiet standing, small angular displacements (~0.5°) of the trunk and leg were identified in raw data. Correspondingly, there were peaks in the power spectra of the angular movements and EMG. While body movement and EMG were coherent with respiration (>0.5), the coherence between respiration and COP displacement was low (<0.2). The amplitude of movement and coherence was increased when respiration was increased. The present data suggest that the postural disturbance that results from respiratory movement is matched, at least partly, and counteracted by small angular displacements of the lower trunk and lower limbs. Thus, stability in quiet stance is dependent on movement of multiple body segments and control of equilibrium cannot be reduced to control of a single joint.

Study of differences in peripheral muscle strength of lean versus obese women: an allometric approach

OBJECTIVE: To investigate whether peripheral muscle strength is significantly different between lean and obese women controlled for age and physical activity, using an allometric approach.DESIGN: Cross-sectional study of isometric handgrip and isokinetic leg and trunk muscle strength.SUBJECTS: 173 obese (age 39.9±11.4 y, body mass index (BMI) 37.8±5.3 kg/m2) and 80 lean (age 39.7±12.2 y, BMI 22.0±2.2 kg/m2) women.MEASUREMENTS: Anthropometric measures (weight, height) and body composition (bioelectrical impedance method), isometric handgrip (maximal voluntary contraction on the Jamar dynamometer), isokinetic trunk flexion–extension, trunk rotation, and knee flexion–extension (Cybex dynamometers).RESULTS: Absolute isokinetic strength output (that is, strength uncorrected for fat-free mass) was larger in obese compared to lean women, except for knee flexion and isometric handgrip, which were not significantly different (P>0.05). Pearson correlation coefficients between strength measures and fat-free mass (kg) were low to moderate both in lean (r=0.28–0.53, P<0.05) and in obese (r=0.29–0.49, P<0.001) women. There was no correlation with fat mass (kg) in the lean, whereas in the obese women a weak positive relation could be observed for most isokinetic data (r=0.21–0.39, P<0.01). When correcting for fat-free mass (raised to the optimal exponent determined by allometric scaling), all strength measurements were at least 6% lower in obese when compared to the lean women, except for trunk flexion, which was at least 8% stronger in obese women.DISCUSSION: The higher absolute knee extension strength measures of leg and the similar extension strength of the trunk in the obese sample compared to the lean might be explained by the training effect of weight bearing and support of a larger body mass. However when the independent effect of fat-free mass is removed, these strength measures, as well as oblique abdominal muscle and handgrip strength, turned out to be lower in obese women. These observations could be the reflection of the overall impairment of physical fitness as a consequence of obesity and its metabolic complications.

Effect of paraspinal muscle vibration on position sense of the lumbosacral spine.

STUDY DESIGN A two-group experimental design with repeated measures on one factor was used. OBJECTIVES To investigate the role of the muscle spindles of the paraspinal muscles in lumbosacral position sense of healthy individuals. SUMMARY OF BACKGROUND DATA Muscle spindles are recognized to be important mediators for position and movement sense in peripheral joints, and they are very sensitive to mechanical vibration. However, little is known about their role in the control of lumbosacral spine positioning. METHODS Twenty-five young individuals with no low back pain were assigned at random to an experimental or control group. Proprioceptive information of the multifidus muscle spindles was distorted in half of the trials in 16 individuals by manually applying vibration (70 Hz, 0.5 mm amplitude) for approximately 5 seconds. The control group (n = 9) only heard the vibrator noise during repositioning of the lumbosacral spine. Repositioning accuracy in the sitting position was estimated by calculating the mean absolute error, constant error, and variable error among six criteria and reproduction sacral tilt angles. RESULTS Multifidus muscle vibration induced a significant muscle lengthening illusion through which the members of the experimental group undershot the target position (F(1,15) = 30.77, P < 0.0001). The position sense scores of the control group displayed no significant differences across trials (F(1,8) = 0.56, P > 0.05). CONCLUSIONS The findings suggest that precise muscle spindle input of the paraspinal muscles is essential for accurate positioning of the pelvis and lumbosacral spine in a sitting posture.

The effect of aging on dynamic position sense at the ankle

The present study addressed whether dynamic position sense at the ankle--or sense of position and velocity during movement--shows a similar decline as a result of aging as previously described for static position sense and movement detection threshold. Additionally, the involvement of muscle spindle afferents in the possible age-related decline was studied. To assess dynamic position sense, blindfolded subjects had to open the hand briskly when the right ankle was rotating passively through a prescribed target angle. To assess the involvement of muscle spindles, the effect of tibialis anterior vibration was studied. The results showed that aging lead to a significant increase in deviation from the target angle at hand opening as well as in variability of performance. Vibration resulted in larger undershoot errors in the elderly compared to the young adults, suggesting that the age-related decline in performance on the dynamic position sense task is not (solely) due to muscle spindle function changes. Alternatively, this degeneration might be due to altered input from other sources of proprioceptive input, such as skin receptors. The elderly subjects did show a beneficial effect of practice with the task, which may provide solid fundaments for rehabilitation.

The Effect of Inspiratory Muscles Fatigue on Postural Control in People With and Without Recurrent Low Back Pain

Study Design. A 2-group experimental design. Objective. To determine postural stability and proprioceptive postural control strategies of healthy subjects and subjects with recurrent low back pain (LBP) during acute inspiratory muscles fatigue (IMF). Summary of Background Data. People with LBP use a more rigid proprioceptive postural control strategy than control subjects during postural perturbations. Recent evidence suggests that respiratory movements create postural instability in people with LBP. The role of the respiratory muscles in postural control strategies is unknown, but can be studied by inducing acute IMF. Methods. Postural control was evaluated in 16 people with LBP and 12 healthy controls, both before and after IMF. Center of pressure displacement was determined on a force plate to evaluate postural stability. Proprioceptive postural control strategies were examined during vibration of the triceps surae muscles or lumbar paraspinal muscles, while standing on both a stable and unstable support surface and without vision. Proprioceptive postural control strategies were determined by examining the ratio of mean center of pressure displacement measured during triceps surae muscles vibration to that measured during lumbar paraspinal muscles vibration. Results. After IMF, control subjects showed a significantly larger sway compared to the unfatigued condition while standing on an unstable support surface (P < 0.05). IMF induced an increased reliance on proprioceptive signals from the ankles, which resembled the postural control strategy used by people with LBP (P < 0.05). Subjects with LBP showed that same ankle steered postural control strategy in the unfatigued and IMF states (P > 0.05). Conclusion. After IMF, control subjects use a rigid proprioceptive postural control strategy, rather than the normal “multisegmental” control, which is similar to people with LBP. This results in decreased postural stability. These results suggest that IMF might be a factor in the high recurrence rate of LBP.

Proprioceptive changes impair balance control in individuals with chronic obstructive pulmonary disease.

Introduction Balance deficits are identified as important risk factors for falling in individuals with chronic obstructive pulmonary disease (COPD). However, the specific use of proprioception, which is of primary importance during balance control, has not been studied in individuals with COPD. The objective was to determine the specific proprioceptive control strategy during postural balance in individuals with COPD and healthy controls, and to assess whether this was related to inspiratory muscle weakness. Methods Center of pressure displacement was determined in 20 individuals with COPD and 20 age/gender-matched controls during upright stance on an unstable support surface without vision. Ankle and back muscle vibration were applied to evaluate the relative contribution of different proprioceptive signals used in postural control. Results Individuals with COPD showed an increased anterior-posterior body sway during upright stance (p = 0.037). Compared to controls, individuals with COPD showed an increased posterior body sway during ankle muscle vibration (p = 0.047), decreased anterior body sway during back muscle vibration (p = 0.025), and increased posterior body sway during simultaneous ankle-muscle vibration (p = 0.002). Individuals with COPD with the weakest inspiratory muscles showed the greatest reliance on ankle muscle input when compared to the stronger individuals with COPD (p = 0.037). Conclusions Individuals with COPD, especially those with inspiratory muscle weakness, increased their reliance on ankle muscle proprioceptive signals and decreased their reliance on back muscle proprioceptive signals during balance control, resulting in a decreased postural stability compared to healthy controls. These proprioceptive changes may be due to an impaired postural contribution of the inspiratory muscles to trunk stability. Further research is required to determine whether interventions such as proprioceptive training and inspiratory muscle training improve postural balance and reduce the fall risk in individuals with COPD.

Lumbosacral repositioning accuracy in standing posture: a combined electrogoniometric and videographic evaluation

OBJECTIVE To provide a new method of measuring repositioning accuracy in the lumbosacral spine in a standing position. DESIGN A test-retest and parallel-forms reliability testing was performed. BACKGROUND The contribution of proprioception to lumbar muscle function and to the stability of the lumbar spine is relatively unknown. METHOD A piezoresistive electrogoniometer attached to the skin over the sacrum and a three-dimensional video analysis system with reflective markers on anatomical landmarks were both employed to measure the repositioning accuracy of pelvic tilting in standing. Eleven subjects without low back pain participated in this study. RESULTS The overall mean repositioning accuracy was 1.87 degrees. Probability values from repeated measures ANOVA revealed no significant mean absolute error (AE) differences between sessions. Correlation coefficients between electrogoniometer and 3-D video analysis measurements of position sense ranged from 0.84 to 0.97. CONCLUSIONS The proposed instruments and method are adequate for measuring lumbosacral repositioning accuracy. Healthy subjects are capable of repositioning their pelvis and back precisely. RELEVANCE A reliable method assessing the lumbosacral repositioning accuracy can add insight into neuromuscular dysfunction as a cause of mechanical low back pain.

Altered interpretation of neck proprioceptive signals in persons with subclinical recurrent neck pain.

OBJECTIVE To evaluate whether subjects with subclinical recurrent neck pain have an altered interpretation of neck proprioceptive signals. DESIGN A comparative group design. SUBJECTS Twelve subjects with recurrent neck pain and 12 control subjects. METHODS The shoulder, head, trunk and whole-body position were measured under the following conditions: active and passive elevation and depression of the right shoulder and vibration of the trapezius muscle. RESULTS During passive shoulder movements both groups moved their head in the opposite direction (p<0.05). During passive elevation subjects with recurrent neck pain showed a significant over-appraisal of shoulder position. Both groups responded similarly to active movements. Subjects with recurrent neck pain and control subjects showed similar trunk and head-to-trunk movements during shoulder movements. Subjects with recurrent neck pain, however, made larger movements compared with healthy subjects (p<0.05). During trapezius muscle vibration similar whole-body movements were found in both groups. CONCLUSION These results show a modified interpretation of neck proprioceptive signals in subjects with recurrent neck pain and may reflect an offset in the egocentric reference frame or a decreased capacity to switch between reference frames. Better insight into these mechanisms might lead to better evaluation and treatment of subjects with recurrent neck pain and to a reduction in recurrent episodes.