Bertrand Arsenault

Maximal grip force in chronic stroke subjects and its relationship to global upper extremity function

Objectives: Previous studies have shown that recovery of recordable grip strength in acute stroke subjects is one of the most sensitive assessments of initial upper limb recovery and a good prognostic factor for latter recovery. The objectives of this study were to test the reliability of maximal voluntary grip force (MVGF) measures and evaluate the relationship between paretic grip strength deficit and paretic upper extremity function in chronic stroke subjects. Design: Over a three-week period, bilateral MVGF was assessed three times with a modified strain gauge dynamometer in 15 chronic stroke subjects and 10 control subjects. The paretic MVGF deficit was expressed in relation to the MVGF of the nonaffected hand. Outcome measures: Upper extremity function in stroke subjects was measured using the Fugl-Meyer, the upper extremity performance test for the elderly (TEMPA), Box and Block and finger-to-nose tests. Results: MVGF measures in both groups of subjects demonstrated good reliability (intraclass correlation, ICC >0.86) and low standard error measurements (SEM). The paretic MVGF of the stroke subjects was greatly impaired in comparison to the control subjects. Results of linear and quadratic regressions analyses show that this impairment was significantly correlated (p <0.01) with the performance of the stroke subjects on the four upper extremity function tests. The percentages of variances explained by the MVGF deficit on all four upper extremity tests varied from 62% to 78% for the linear regressions and from 72% to 93% for the quadratic regressions. Conclusions: These results suggest that the paretic maximal grip strength, normalized with the maximal grip strength on the nonaffected side, appears to be a valuable outcome measure of upper extremity function in chronic stroke subjects.

Low-back-pain related disability: An integration of psychological risk factors into the stress process model

&NA; The purpose of this study was to verify the usefulness of an adaptation of the stress process model in organizing the psychological variables associated with the development of low‐back‐pain related disability. French‐speaking Canadian workers on compensated sick leave (N = 439) due to recent occupational low back pain (LBP) were evaluated during the sub‐acute stage of LBP (between 30 and 83 days after injury). They were assessed for the following factors: life events, injury‐specific cognitive appraisal, emotional distress, avoidance coping, and functional disability. Confirmatory factor analyses were used to test and modify the measurement model. An important modification in the measurement model was the association of catastrophizing with the emotional distress factor. During the sub‐acute stage, path analyses revealed a satisfactory fit of the following model (the following coefficients are standardized): (a) life events (.30) and cognitive appraisal (.42) explained emotional distress (r2 = .30); (b) emotional distress (.42) and cognitive appraisal (.36) explained the use of avoidance coping (r2 = .45); and (c) emotional distress (.24) and avoidance coping (.56) explained functional disability (r2 = .53). The stress model tested here reaffirms the importance of life events in the development of disability through the more established emotional distress factor. Also, cognitive appraisal appears to have an indirect effect on disability through activity avoidance and distress. This adaptation of the stress model makes it possible to integrate risk factors into a reduced set of meaningful factors and proposes a more general adaptation explanation of disability than the specific fear‐avoidance model.

Characterization of global synkineses during hand grip in hemiparetic patients

OBJECTIVE Global synkineses are defined as nonpurposive associated movements on the involved side of hemiparetic subjects that are triggered during a voluntary movement. The purpose of this study was to characterize the intensity and pattern of upper limb global synkineses in hemiparetic subjects with a static biarticular dynamometer and electromyography during maximal progressive hand grip on the unaffected side. DESIGN Survey, convenience sample. SETTINGS University secondary care rehabilitation center. DATA SET Global synkineses (ie, torques and electromyographic activities) in patients with severe (n = 8) and moderate (n = 7) deficits in motor performance, as evaluated by the Fugl-Meyer assessment, were compared with those obtained in a group of healthy subjects (n = 11). Clinically the subjects from the severe deficit group were more spastic and showed less strength at the elbow than the subjects from the moderate deficit group. RESULTS Results of analyses of variance showed significant increases of shoulder torque in flexion and internal rotation, and elbow torque in flexion, with increasing force exertion during contralateral hand grip in subjects with severe deficits (p < .05). Furthermore, in these subjects increases of electromyographic activity were also observed in biceps brachii, brachioradialis, and triceps brachii muscles with increasing hand grip force levels. In contrast, no significant torques or electromyographic increases were observed in subjects with moderate deficits and in control subjects during contralateral hand grip exertions. CONCLUSION These results provide a quantitative assessment of the kinematic and electromyographic patterns of global synkineses and their correlates with clinical observations. Within the limits of the experimental results presented in this study, it is suggested that global synkineses result from contralateral overflow of the voluntary command to hyperexcitable motoneuron pools.

An interdisciplinary clinical practice model for the management of low-back pain in primary care: the CLIP project

BackgroundLow-back pain is responsible for significant disability and costs in industrialized countries. Only a minority of subjects suffering from low-back pain will develop persistent disability. However, this minority is responsible for the majority of costs and has the poorest health outcomes. The objective of the Clinic on Low-back pain in Interdisciplinary Practice (CLIP) project was to develop a primary care interdisciplinary practice model for the clinical management of low-back pain and the prevention of persistent disability.MethodsUsing previously published guidelines, systematic reviews and meta-analyses, a clinical management model for low-back pain was developed by the project team. A structured process facilitating discussions on this model among researchers, stakeholders and clinicians was created. The model was revised following these exchanges, without deviating from the evidence.ResultsA model consisting of nine elements on clinical management of low-back pain and prevention of persistent disability was developed. The models two core elements for the prevention of persistent disability are the following: 1) the evaluation of the prognosis at the fourth week of disability, and of key modifiable barriers to return to usual activities if the prognosis is unfavourable; 2) the evaluation of the patients perceived disability every four weeks, with the evaluation and management of barriers to return to usual activities if perceived disability has not sufficiently improved.ConclusionA primary care interdisciplinary model aimed at improving quality and continuity of care for patients with low-back pain was developed. The effectiveness, efficiency and applicability of the CLIP model in preventing persistent disability in patients suffering from low-back pain should be assessed.

EFFECT OF PELVIC STABILIZATION AND HIP POSITION ON TRUNK EXTENSOR ACTIVITY DURING BACK EXTENSION EXERCISES ON A ROMAN CHAIR

OBJECTIVE To assess the effect of pelvic stabilization and hip position on the electromyographic activity of trunk extensors during Roman chair exercise. A secondary objective was to compare genders. DESIGN Repeated measures. SUBJECTS Eleven men and 11 women volunteers. METHODS Five trunk flexion-extension cycles for 3 Roman chair conditions: (i) pelvis unrestrained; (ii) pelvis restrained; and (iii) hip at 40 degrees flexion. Electromyographic signals were recorded on the back muscles, as well as on the gluteus maximus and biceps femoris. The percentage of electromyographic amplitude relative to the maximal activity was used to assess the level of muscular activation of each muscle group across the exercises. RESULTS For both genders, the Roman chair conditions did not influence the activity of the back and gluteus muscles. The hip-at-40 degrees-flexion condition significantly reduced the activity of the biceps femoris (average of 4-18%) relative to the other 2 conditions. Gender differences were observed on the activity of the biceps femoris in all Roman chair conditions. CONCLUSION The hip-at-40 degrees-flexion condition would allow the Roman chair exercise to train the targeted back muscles more specifically by overloading them over a longer duration in order to induce physiological changes.

A static dynamometer measuring multidirectional torques exerted simultaneously at the hip and knee

The function of a static dynamometer measuring torques exerted simultaneously in the different anatomical planes of the hip (flexion-extension, abduction-adduction and internal-external rotation) and knee (flexion-extension) is described. Muscular torques were calculated in real time using a desktop computer from measurements of orthogonal forces applied at two locations and the lever arm values measured in each subject. The reliability of the force transducers was explored by examining their output, using calibrated weights, on three different days. The results were identical over this period of time, indicating that the transducers are highly reliable. A mechanical simulator of a lower limb was constructed to generate specific or combined torques of known values at the hip and knee. The torques measured by the dynamometer were found to be highly concordant with the known torques applied by the simulator, indicating that the torque measurements were valid. The usefulness of the dynamometer is demonstrated by evaluating the activity of the rectus femoris and biceps femoris muscles during static efforts exerted in various directions at the hip. In addition, the mechanical action of biarticular muscles at the hip was evaluated by quantification of hip torques during efforts exerted at the knee. From these results, it has been concluded that the present biarticular and multidirectional dynamometer is a valid, reliable and precise instrument that may prove to be useful in evaluating the muscular function of the lower limb.