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Background: Lumbosacral orthosis (LSO) and/or the isolated contraction of the transversus abdominis muscle by the abdominal drawing-in maneuver (ADIM) can increase lumbar stiffness, consequently influencing postural control. The purpose of this study was to compare the effects of LSO and ADIM on postural control during two balance tasks and determine their reliability. Methods: Twenty participants (50% men) randomly performed three experimental conditions: 1) without lumbar stabilization, 2) with LSO), and 3) with ADIM. Each experimental condition was tested in two postural tasks: semi-tandem and one-legged stance on a force platform for 30 seconds, while the Center of pressure postural (COP) parameters were computed. Results: The two methods of lumbar stabilization were comparable and did not significantly reduce the COP values across time, even though a few individuals presented a change in their COP data above the levels of measurement errors. The reliability of these measurements was generally acceptable and sometimes excellent ([Image: see text] 0.90 and ≤10% error measurement). Conclusions: Both LSO and isolated contraction of the transversus abdominis muscle by ADIM do not change postural control in one-legged stance and in semi-tandem tasks. These results have implications for use or not these methods for postural control on a rehabilitation perspective.

Introduction: Low back pain (LBP) is the most common musculoskeletal complaint in pregnancy, being responsible for many negative impacts. Objective: To evaluate the effect of LBP on static and dynamic balance in pregnant women and whether pregnancy mediates the results compared to non-pregnant women. Methods: 44 women (mean age 30 yrs) participated voluntarily in this study: 16 pregnant women with LBP starting in pregnancy, 14 pregnant women without LBP and 14 non-pregnant women as a group control. Participants were assessed for static postural balance using a force platform and dynamic mobility balance using the Timed Up and Go (TUG) test. Results: The pregnant women with LBP showed significant (P < 0.04, for mean, d= 1,2) poor postural balance in static tests (force platform), in the area of COP eyes open. In dynamic balance (TUG test), statistical difference was found between the groups (P 0.038) and the effect size were moderate to strong in the comparison between the three groups. The most sensitive differences were reported mainly between pregnant women with LBP versus non-pregnant control group in balance measures from force platform. Conclusion: The findings indicate that LBP associated to pregnant clinical status can decrease the balance capacity in women. These results have implication for balance evaluation and retraining in pregnant women with and without LBP from rehabilitation or prevention programs.

Introduction: Parkinson’s disease is most prevalent among elderly people, 65 years and over, and leads to an alteration in motor control associated with postural instability. Current evidence shows that postural control decreases with the aging process. In addition, postural control is more altered in healthy aged men than in women. Until today, few studies have evaluated the combined impact of Parkinson’s disease and sex on postural control. This review has allowed to evaluate the impact of Parkinson’s disease and sex on postural control measurements in elderly people. Methodology: Studies have been selected from two main databases: PubMed and EBSCO using the keywords “Parkinson”, “postural control OR balance” and “sex”. Articles related to the evaluation of postural control, including men and women with Parkinson’s aged over 65 years old, regardless of stage, were included (n = 179). Articles were excluded if not written in French or English or not presenting original content. Results: Ten (10) studies out of 179 that fulfilled inclusion and exclusion criteria were reported in the final analysis, which cumulates a total of 944 individuals with Parkinson’s (410 women). In general, results show greater postural instability among people with Parkinson’s compared to healthy subjects, and this according to different objective measurements using stabilographic parameters from force platforms. Only two studies out of ten evaluated postural control while briefly considering distinctions between sex, but without showing a significant difference between men and women with Parkinson’s. Parkinson’s severity, length of time of Parkinson’s disease and cognitive state of the person are the three variables with a negative impact on postural control. Conclusion: Older people with Parkinson’s disease have greater postural instability. Sex does not seem to influence the postural control of elderly people with Parkinson’s, although more studies are necessary.

We aimed to determine the neurophysiological pattern that is associated with the development of musculoskeletal pain that is induced by biomechanical constraints. Twelve (12) young healthy volunteers (two females) performed two experimental realistic manual tasks for 30 min. each: (1) with the high risk of musculoskeletal pain development and (2) with low risk for pain development. During the tasks, synchronized electroencephalographic (EEG) and electromyography (EMG) signals data were collected, as well as pain scores. Subsequently, two main variables were computed from neurophysiological signals: (1) cortical inhibition as Task-Related Power Increase (TRPI) in beta EEG frequency band (β.TRPI) and (2) muscle variability as Coefficient of Variation (CoV) from EMG signals. A strong effect size was observed for pain measurement under the high risk condition during the last 5 min. of the task execution, with muscle fatigue, because the CoV has decreased below 18%. An increase in cortical inhibition (β.TRPI &gt, 50%) was observed after the 5th min. of the task in both experimental conditions. These results suggest the following neurophysiological pattern—β.TRPI ≥ 50% and CoV ≤ 18%—as a possible indicator to monitor the development of musculoskeletal pain in the shoulder in the context of repeated and prolonged exposure to manual tasks.

Background Low back pain is common during pregnancy. Lumbar stabilization and stretching exercises are recommended to treat low back pain in the general population. However, few studies have applied the effects of these two interventions in pregnant women with low back pain. Aim To compare the effects of lumbar stabilization and stretching exercises for the treatment of gestational low back pain. Design A pilot randomized clinical trial. Setting Laboratory of Functional Evaluation and Human Motor Performance and physical therapy clinics. Population Initially, 30 pregnant women with low back pain were recruited, of which 24 met the following inclusion criteria: being between 19-29 weeks of gestation; being in prenatal clinical follow-up; having nonspecific mechanical low back pain started in pregnancy; not participating in specific low back pain treatment in the last 3 months. A total of 20 women completed the study (10 each group). Methods The main outcome measures were clinical (pain by Visual Analogue Scale (VAS) and McGill Pain Questionnaire and disability by Roland Morris Questionnaire), and secondary outcome measures were: postural balance (force platform); muscle activation level of multifidus, iliocostalis lumborum, rectus abdominis and external abdominal oblique (electromyography). The women were randomized into two groups for 6 weeks of intervention twice a week for a 50-minute treatment: 1) lumbar stabilization exercise protocol and 2) stretching exercise protocol. Results There was a significant reduction (P=0.03) in pain (1.68 in VAS and 4.81 for McGill questionnaire) for both interventions, but no change in disability score. In addition, both interventions were comparable for a significant improvement in postural stability (in mean d=0.77) for the velocity sway parameter, and significantly increased activation (P>0.05) of the external abdominal oblique muscle after intervention. Conclusions Both modalities (lumbar stabilization and stretching) were efficient for pain reduction, improving balance and increasing one trunk activity muscle after 6 weeks of intervention in pregnant women with low back pain. Clinical rehabilitation impact The present study has implications, especially for clinical decision-making with regard to therapy choice in pregnant women with LBP to reduce pain and improve trunk function as measured through balance performance.

Mechanical vibration of tendons induces large postural reactions (PR-VIB) but little is known about how these reactions vary within and between subjects. We investigated the intra- and inter-individual variability of PR-VIB and determined the reliability of center of pressure (COP) measures. Bipodal postural control (eyes closed) of 30 healthy adults were evaluated using a force platform under 02 conditions: bilateral VIB of the tibialis anterior (TA) and Achilles tendons (ACH-T) at 80 Hz. Each condition consisted of 03 trials of 30 s duration (Baseline: 10 s; VIB: 10 s; POST-VIB: 10 s). The Amplitude and Velocity of the COP in the antero-posterior/medio-lateral (AP/ML) directions were recorded and analyzed according to 5 time-windows incremented every 2 s of vibration (i.e. the first 2 s; 4 s; 6 s; 8 s & 10 s), whereas the COP position/AP was monitored every 0.5 s. All postural parameters increased significantly during TA and ACH-T vibration compared to the Baseline. The reliability of the COP measures showed good ICC scores (0.40-0.84) and measurement errors that varied depending on the duration of VIB time-windows. The COP position/AP reveals a lower intra- and inter-subject variability of PR-VIB in the first 2 s of VIB. The metrological characteristics of PR-VIB should be investigated further to guide their future use by clinicians and researchers.

Postural control declines with age and can be affected by low back pain. Poor balance has been reported in people with chronic low back pain (CLBP), which in turn could be explained by the changes in trunk muscle activation.Are there differences between younger and older adults with and without chronic low back pain (CLBP) on trunk muscle activity during one-legged stance task?Twenty (20) with, and 20 subjects without nonspecific CLBP participated in the study. Each group was comprised of 10 younger (50% males; mean age: 31 years) and 10 older adults (50% males; mean age: 71 years). Subjects performed 3 × 30-second trials of one-legged stance, with eyes open, on a force platform, while surface electromyography (EMG) measurements were obtained bilaterally on the multifidus at L5, iliocostalis lumborum at L3, rectus abdominis and biceps femoris muscles.EMG amplitude analysis was processed by the Root Mean Square (250 ms window epochs) and normalized by the peak of activation during the balance tasks, to determine the muscular activity of each muscle.Participants with CLBP presented 15% lower lumbar muscle activation (p 0.05), and 23% higher co-activation (ratio between rectus adominis by multifidus) than participants without CLBP, regardless of age. Significant differences (p 0.05) between older and young groups were observed only for lower lumbar muscles (mean 24% lower in older than younger adults) and rectus adominis muscles (mean 17% lower in older than younger adults).CLBP individuals have different trunk muscle activity than those without CLBP, and older adults exhibit lower trunk activation during one-legged stance balance task. The use of the EMG in evaluation of trunk neuromuscular function during one-legged stance may thus be a valuable tool when assessing balance in CLBP and older people.

Introduction The task of evaluating workers’ capacity to return to their pre-injury employment or other jobs continues to pose a daily challenge for clinicians. In this study, a concept frequently used in the field of ergonomics, the margin of manoeuvre (MM), was applied during the rehabilitation process. The study identified the indicators of the MM taken into account during the return to work of workers with musculoskeletal disorders. Methods This study used a multiple-case design. A case was defined as a dyad comprising a worker admitted to a work rehabilitation program and the clinician who was managing the return-to-work process. The results were then validated with investigators and expert ergonomists, through group interviews. Content analyses were performed using the conceptual framework for the work activity model adapted from Vezina and the procedures recommended by Miles and Huberman. Results A total of 11 workers, five clinicians, two experts and two investigators participated in this study. The interview analysis process resulted in a more detailed definition of the MM and the identification of 50 indicators. The indicators were classified according to six dimensions: (1) work context; (2) employer’s requirements and expectations; (3) means and tools; (4) worker’s personal parameters; (5) work activity; and (6) impacts of the work situation. Conclusions The more specific indicators identified in this study will allow for more systematic observation of the MM. Subsequent studies will seek to link each indicator described in the model with a specific method of observation.

North American workers usually stand while working, and prolonged standing is associated with discomfort and cardiovascular problems. Moving may alleviate the problems, but optimum mobility is unknown. The effects of variations in mobility were explored among (1) 34 health care workers whose symptoms of orthostatic intolerance (OI) were recorded after work; (2) 45 factory and laundry workers. Postures were observed over a workday and blood pressure (BP) and heart rate (HR) of both groups were recorded before and after work. Among health care workers, 65% manifested OI symptoms. In a multiple logistic regression, presence of ⩾1 symptom of OI was associated with static postures and being female (p=0.001). More static standing was associated with a larger drop in BP (p=0.04) in both populations. The results suggest that more static standing postures are associated with OI and musculoskeletal symptoms and with a subclinical drop in BP.

Inadequate postures adopted by an operator at work are among the most important risk factors in Work-related Musculoskeletal Disorders (WMSDs). Although several studies have focused on inadequate posture, there is limited information on its identification in a work context. The aim of this study is to automatically differentiate between adequate and inadequate postures using two wearable devices (helmet and instrumented insole) with an inertial measurement unit (IMU) and force sensors. From the force sensors located inside the insole, the center of pressure (COP) is computed since it is considered an important parameter in the analysis of posture. In a first step, a set of 60 features is computed with a direct approach, and later reduced to eight via a hybrid feature selection. A neural network is then employed to classify the current posture of a worker, yielding a recognition rate of 90%. In a second step, an innovative graphic approach is proposed to extract three additional features for the classification. This approach represents the main contribution of this study. Combining both approaches improves the recognition rate to 95%. Our results suggest that neural network could be applied successfully for the classification of adequate and inadequate posture.

Transcranial magnetic stimulation (TMS) studies investigating motor cortex reorganization in clinical populations use a variety of measurements, with some performed at rest and others with the muscle slightly contracted. Surprisingly there are still a limited number of studies focusing on relationship between TMS-measures obtained at rest and during active muscle contraction in healthy individuals. The purpose of this study was to: (1) compare resting and active TMS-measures and assess their association; (2) determine their respective short- and long-term reliability. Motor threshold (MT), motor evoked potentials (MEP) amplitude, map area, normalized map volume, map center of gravity (CoG) and short-interval intracortical inhibition (SICI) of the first dorsal interosseous (FDI) muscle were assessed in 12 healthy subjects. Subjects were tested three times (with a short (four days) and a long (>1 month) inter-session interval). No significant difference was found between resting and active measures, except for MT. Active MT was on average at 82% of resting MT. Good short- and long-term reliability were found for MT and CoG (in resting and active conditions), for the SICI and MEP amplitude at rest and for the normalized map volume under active condition. In conclusion, maps of FDI muscle obtained at rest and during active contraction are very similar to each other in healthy individuals when differences in MT are taken into account. Most TMS measures present good reliability when obtained under the appropriate condition, with comparable short-term and long-term reliability.

North American workers usually stand while working, and prolonged standing is associated with discomfort and cardiovascular problems. Since prolonged sitting is also associated with health problems, and standing postures differ as to mobility and access to seating, it is desirable to identify an optimal mix of postures. As a step towards this identification, it is desirable to develop indicators of potential health effects that respond to changes in work requirements. We observed 65 subjects who usually stood at work, in four types of workplaces. Pressure-pain threshold (PPT) recorded on the plantar surface was used as an indicator of discomfort and arterial blood pressure was used as an indicator of cardiovascular effects. PPT after work was significantly lower than that before work. Sitting for even a small part of the day appeared to be protective. The effects of static vs. dynamic work on PPT and arterial blood pressure may differ.

This paper aimed to demonstrate the contribution of the research performed by the musculoskeletal disorders (MSD) Research Axis group of the Quebec Occupational Health and Safety Research Network towards better understanding of work-related MSD (WMSD) development and prevention. Although the group targets its work to the Quebec population, its work has significant impact around the world, placing MSD axis members and knowledge and expertise created in Quebec on the international map. Results from the contribution of members are relevant, primarily in the demonstration of the implication of physical workload as well as organizational and psychosocial work-related factors in the development of WMSDs. Also, members have demonstrated that gender, sex, social class, age and ethno-cultural groups interact in various ways with WMSD determinants. Efforts are devoted towards improving understanding of the physiological responses linked with MSDs, which could also lead to new workplace practices in rehabilitation. The group emphasizes the integration of prevention procedures from the design stage to the workplace intervention. Members have proposed research-based tools for best practices at work and also an original conceptual model as a key, novel element of a theoretical conceptualization of WMSDs. Moreover, the group focuses on improving WMSD surveillance, using multiple sources of information, providing information on newly identified health risks and developing new methods of assessing risk in order to effectively prevent disability in the working population. Finally, results from research of the MSD axis group have implications for orienting legal processes, improving legal recognition of MSDs as occupational diseases, and contributing to the evolution of legal thinking. However, much remains to be done. To that end, the group plans and encourages new initiatives for further advancement. In conclusion, the originality of the work places the group in a favourable position to address the complexity underlying WMSDs, combining expertise that enriches fundamental, clinical and population-based research., Le présent article a pour but de démontrer la contribution de la recherche effectuée par le regroupement stratégique troubles musculo-squelettiques (TMS) du Réseau de recherche en santé et sécurité du travail en vue de mieux comprendre le développement et la prévention des troubles musculo-squelettiques liés au travail. Bien que la cible du groupe soit la population québécoise, son travail a un impact important ailleurs dans le monde, plaçant les membres du regroupement, leurs connaissances et l’expertise qu’ils ont acquise au Québec sur l’échiquier international. Les résultats qui ont découlé de la contribution des membres sont pertinents, particulièrement en ce qui touche la démonstration des effets de la charge de travail physique de même que des facteurs organisationnels et psychosociaux du monde du travail dans le développement des troubles musculo-squelettiques liés au travail. De plus, les membres ont prouvé que le sexe, le genre, la classe sociale, l’âge et les groupes ethnoculturels interagissent de diverses façons avec les déterminants des troubles musculo-squelettiques liés au travail. Des efforts ont été entrepris pour mieux comprendre les réponses physiologiques liées aux troubles musculo-squelettiques, et ils pourraient bien amener de nouvelles pratiques de réhabilitation en milieu de travail. Le groupe souligne l’intégration des procédures de prévention au départ de la conception de celles-ci jusqu’à l’étape d’intervention en milieu de travail. Les membres ont proposé des outils basés sur la recherche pour instaurer des pratiques exemplaires en milieu de travail de même qu’un modèle conceptuel original comme étant une clé, un élément novateur dans la conceptualisation théorique des troubles musculo-squelettiques liés au travail. De plus, le groupe met l’accent sur l’amélioration du dépistage des troubles musculo-squelettiques liés au travail en utilisant de multiples sources d’information, en fournissant de l’information sur les nouveaux risques identifiés pour la santé et en mettant sur pied de nouvelles méthodes d’évaluation des risques pour prévenir de façon efficace ces troubles au sein de la population au travail. Enfin, les résultats de la recherche du regroupement stratégique sur les TMS ont des implications pour l’orientation des processus juridiques, l’amélioration de la reconnaissance juridique des troubles musculo-squelettiques comme maladies professionnelles, et la contribution à l’évolution de la pensée juridique. Toutefois, il reste encore beaucoup à faire. Et dans cette optique, le regroupement prévoit et encourage de nouvelles initiatives pour continuer de faire avancer la science. En conclusion, l’originalité de ce travail met le regroupement dans une position favorable pour se pencher sur la complexité qui sous-tend les troubles musculo-squelettiques liés au travail en combinant des expertises qui sauront enrichir la recherche fondamentale, clinique et basée sur les populations., El presente artículo busca demostrar la contribución de la investigación efectuada por el reagrupamiento estratégico TMS (trastorno musculo-esqueléticos) de la Red de investigación en salud seguridad ocupacional con el objetivo de comprender mejor el desarrollo y la prevención de los trastornos musculo-esqueléticos vinculados al trabajo. Aunque la mira del grupo sea la población quebequense, su trabajo tiene un impacto importante en otras partes del mundo, posicionando en el ámbito internacional los miembros del reagrupamiento, sus conocimientos y la pericia adquirida en el Quebec. Los resultados que han derivado de la contribución de los miembros son pertinentes, particularmente en lo que se refiere a la demostración de los efectos de la carga de trabajo física así como de los factores organizacionales y psicosociales del mundo del trabajo en el desarrollo de trastornos musculo-esqueléticos vinculados al trabajo. Además, los miembros han probado que el sexo, el género, la clase social, la edad y los grupos etnoculturales interactúan de diversas maneras con los determinantes de los trastornos musculo-esqueléticos. Se han desarrollado esfuerzos para comprender mejor las respuestas fisiológicas vinculadas a los trastornos musculo-esqueléticos, y éstos podrían aportar nuevas prácticas de rehabilitación en el medio de trabajo. El grupo resalta la integración de procedimientos de prevención al inicio de la concepción de dichas prácticas hasta la etapa de la intervención en el lugar de trabajo. Los miembros han propuesto útiles basados en la investigación para instaurar prácticas ejemplares en el lugar de trabajo y un modelo conceptual original que constituye una clave, un elemento innovador en la conceptualización teórica de los trastornos musculo-esqueléticos vinculados al trabajo. Además, el grupo pone el énfasis en la mejora del despistaje de los trastornos musculo-esqueléticos vinculados al trabajo utilizando para ello múltiples fuentes de información, procurando la información sobre los nuevos riesgos de salud identificados e implementando nuevos métodos de evaluación de riesgos para prevenir de manera eficaz esos trastornos en el seno de la población trabajadora. Finalmente, los resultados de la investigación del reagrupamiento estratégico sobre los TME tienen implicaciones para la orientación de los procesos jurídicos, la mejora del reconocimiento jurídico de los TME como enfermedades ocupacionales, y la contribución a la evolución del pensamiento jurídico, Sin embargo, queda todavía mucho por hacer. Y en esta óptica, el reagrupamiento prevé y alienta nuevas iniciativas para continuar a hacer avanzar la ciencia. En conclusión, la originalidad de este trabajo ofrece al reagrupamiento una posición favorable para abocarse a la complejidad subyacente a los trastornos musculo-esqueléticos vinculados al trabajo, combinando las calificaciones expertas que sabrán enriquecer la investigación fundamental, clínica y empírica, basada en las poblaciones.