Biomedical subjects

Sylvain Grenier

Publications and source records attributed to Sylvain Grenier.

5 recordsLinked to original sources

PubMed2004

Quantifying tissue loads and spine stability while performing commonly prescribed low back stabilization exercises.

STUDY DESIGN: A quantitative biomechanical comparison of seven different lumbar spine "stabilization exercises." OBJECTIVES: The purpose of this research was to quantify lumbar spine stability resulting from the muscle activation patterns measured when performing selected stabilization exercises. SUMMARY OF BACKGROUND DATA: Many exercises are termed "stabilization exercises" for the low back; however, limited attempts have been made to quantify spine stability and the resultant tissue loading. Ranking resultant stability together with spinal load is very helpful for guiding clinical decision-making and therapeutic exercise design. METHODS: Eight stabilization exercises were quantified in this study. Spine kinematics, external forces, and 14 channels of torso EMG were recorded for each exercise. These data were input into a modified version of a lumbar spine model described by Cholewicki and McGill (1996) to quantify stability and L4-L5 compression. RESULTS: A rank order of the various exercises was produced based on stability, muscle activation levels, and lumbar compression. CONCLUSIONS: Quantification of the calibrated muscle activation levels together with low back compression and resultant stability assists clinical decisions regarding the most appropriate exercise for specific patients and specific objectives.

Adult↗

PubMed2004

Determining the stabilizing role of individual torso muscles during rehabilitation exercises.

STUDY DESIGN: A systematic biomechanical analysis involving an artificial perturbation applied to individual lumbar muscles in order to assess their potential stabilizing role. OBJECTIVES: To identify which torso muscles stabilize the spine during different loading conditions and to identify possible mechanisms of function. SUMMARY OF BACKGROUND DATA.: Stabilization exercises are thought to train muscle patterns that ensure spine stability; however, little quantification and no consensus exists as to which muscles contribute to stability. METHODS: Spine kinematics, external forces, and 14 channels of torso electromyography were recorded for seven stabilization exercises in order to capture the individual motor control strategies adopted by different people. Data were input into a detailed model of the lumbar spine to quantify spine joint forces and stability. The EMG signal for a particular muscle was replaced either unilaterally or bilaterally by a sinusoid, and the resultant change in the stability index was quantified. RESULTS: A direction-dependent-stabilizing role was noticed in the larger, multisegmental muscles, whereas a specific subtle efficiency to generate stability was observed for the smaller, intersegmental spinal muscles. CONCLUSIONS: No single muscle dominated in the enhancement of spine stability, and their individual roles were continuously changing across tasks. Clinically, if the goal is to train for stability, enhancing motor patterns that incorporate many muscles rather than targeting just a few is justifiable.

Adult↗

PubMed2003

Previous history of LBP with work loss is related to lingering deficits in biomechanical, physiological, personal, psychosocial and motor control characteristics.

A cross-sectional retrospective study was made of currently asymptomatic workers who perform physically demanding jobs. To further quantify the association between various biomechanical, physiological, personal psychosocial and motor control parameters that linger due to a history of low back disorders. Seventy-two workers were recruited from heavy industry, 26 of whom had a history of disabling low back disorders (LBDs) sufficient to miss work while the others did not. The strength of the study lies in the many detailed variables measured. Having a history of low back disorders was found to be associated with a larger waist girth, a greater potential for low back pain chronicity as predicted from psychosocial questionnaires, perturbed flexion to extension strength and endurance ratios, and widespread motor control deficits across a variety of tasks, some of which resulted in high back loads. In those workers who had missed work due to back disorders, the length of time since their last disabling episode was 261 weeks on average, suggesting that multiple deficits may remain for a period of time. Having a history of LBD is associated with changes in attitudes, in body composition, and in the way people move, load their backs and respond to a variety of motor and stability challenges.

Absenteeism↗

PubMed2003

Coordination of muscle activity to assure stability of the lumbar spine.

The intention of this paper is to introduce some of the issues surrounding the role of muscles to ensure spine stability for discussion -- it is not intended to provide an exhaustive review and integration of the relevant literature. The collection of works synthesized here point to the notion that stability results from highly coordinated muscle activation patterns involving many muscles, and that the recruitment patterns must continually change, depending on the task. This has implications on both the prevention of instability and clinical interventions with patients susceptible to sustaining unstable events.

Biomechanical Phenomena↗

PubMed2003

The effect of test position on lumbar spine position sense.

STUDY DESIGN: Repeated-measures experimental design. OBJECTIVES: The purpose of this study was to compare lumbar spine position sense in 3 test positions (standing, sitting, and 4-point kneeling [FPK]) to determine if position sense is affected by test position. BACKGROUND: Several recent studies have tested position sense in the spine. There has, however, been no consistency in the testing methods or test positions used in these studies. METHODS AND MEASURES: Seventy asymptomatic males (range, 20-51 years) volunteered for testing. Active lumbar spine repositioning accuracy and precision was tested 3-dimensionally in 3 test positions (standing, sitting, and FPK) and under 2 conditions (eyes open and blindfolded), using the neutral spine posture as the initial reference position. RESULTS: Both the accuracy and precision of lumbar spine repositioning was found to be significantly affected by test position. Repositioning errors (reflective of accuracy) were significantly larger in FPK than in both sitting and standing, and significantly larger in sitting than in standing, under both eyes-open and blindfolded conditions. Precision of repositioning was significantly less in the FPK position as compared to the standing position. CONCLUSION: The results of this study suggest that test position has a significant effect on the acuity of lumbar spine position sense and should be considered when examining the current literature on spine proprioception.

Adult↗