BACKGROUND:Foam pads are increasingly used on force platforms during balance assessments in order to produce increased instability thereby permitting the measurement of enhanced posturographic parameters. A variety of foam pads providing different material properties have thus been used, although it is still unclear which characteristics produce the most effective and reliable tests. Furthermore, the effects of participant bodyweight on the performance of the foam pads and outcome of the test are unknown. This project investigated how different foam samples affected postural sway velocity in participants of different weights.METHOD:Four foam types were tested according to a modified American Society for Testing and Materials standard method for testing flexible cellular materials. Thirty-six healthy male factory workers divided into three groups according to body mass were tested three times for each of the 13 randomly-selected experimental situations for changes in postural sway velocity in this cross-over study. Descriptive and inferential statistics were used to compare the results and evaluate the difference in sway velocity between mass groups.RESULTS:For the materials considered here, the modulus of elasticity of the foam pads when compressed by 25% of their original heights was inversely proportional to their density. The largest changes in postural sway velocity were measured when the pads of highest stiffness were used, with memory foam pads being the least likely to produce significant changes.CONCLUSIONS:The type of foam pads used in posturography is indeed important. Our study shows that the samples with a higher modulus of elasticity produced the largest change in postural sway velocity during quiet stance. The results suggest that foam pads used for static computerised posturography should 1) possess a higher modulus of elasticity and 2) show linear deformation properties matched to the participants' weight.

Neck muscle fatigue has been shown to alter an individual's balance in a similar way to that reported in subjects suffering from neck pain or subjects that have suffered a neck injury. The main purpose of the present study was to quantify the effects of neck fatigue on neck muscle electromyography (EMG) activity, balance, perceived fatigue and perceived stability. Forty four elite amateur rugby league players resisted with their neck muscles approximately 35% maximum voluntary isometric contraction (MVIC) force for 15 minutes in eight different directions. Sway velocity and surface electromyography were measured. Questionnaires were used to record perceived effort and stability. Repeated measures ANOVA showed that after 15 minutes isometric contraction, significant changes were seen in sway velocity, perceived sway and EMG median frequency. There were no differences in perceived efforts. The changes in sway velocity and median frequency were more pronounced after extension and right and left posterior oblique contractions but there was no significant difference in sway velocity after contraction in the right lateral flexion, right anterior oblique and left anterior oblique direction of contraction. All the subjects showed oriented whole-body leaning in the plane of the contraction. The experiment produced significantly altered and perceived altered balance in this group of physically fit individuals. The results may contribute to our understanding of normal functional capacities of athletes and will provide a basis for further investigation in healthy non-athletes and participants that have suffered neck injuries. This may ultimately help develop accurate and valid rehabilitation outcome measures.

Introduction: Cervical functional capacity outcome measures that are simple and reliable are urgently needed in order permit accurate assessment/reassessment during treatments and rehabilitation. Induced neck muscle fatigue has been shown to alter functional capacities such as balance and kinaesthetic sense in the standing posture. The Rod and Frame Test has also shown promise as a method of assessing the effects of chronic neck pain and injury, but currently only in the sitting position. The objectives of this project were therefore 1) to validate the computerised rod and frame test in the standing posture, and 2) to measure the effects that different cervical muscle fatigue protocol would have on the assessment of the subjective visual vertical and horizontal.Method: The validation of the standing computerised rod and frame test in the standing posture was obtained by comparing results (n = 74) between the sitting and standing positions with the Spearman's correlation coefficient. In addition, agreement between the two methods was analysed with the Bland-Altman method. Participants (n = 56) resisted with their neck muscles approximately 35% maximum isometric voluntary contraction force for 15 minutes on a purpose built apparatus in eight different directions. Wilcoxon signed rank tests analysed changes in horizontal and vertical rod and frame test between the neutral and all different directions of contraction. The changes of recorded unsigned vertical and horizontal errors for the combined frame condition in all situations of isometric contraction were analysed with two respective one-way repeated measures analysis of variance (ANOVA).Discussion: The Spearman's rho and Bland-Altman plots show that the Rod and Frame Test works equally well in sitting and standing positions. After muscle contraction, there were significant increases in error in all participants for both horizontal and vertical rod and frame tests, except after flexion. These errors were predominantly present after fatigue of muscles in the coronal plane of contraction. Proprioception alone cannot explain the difference in the rod and frame results between different muscle groups. It is suggested that an evolutionary advantage of developing improved subjective verticality awareness in the same direction as the main visual field could explain these findings.

The purpose of this study was to develop a thoracic adjusting simulator for chiropractic students to evaluate and improve their adjusting skills, and to test reliability and validity of the device. Attempting to make an adjustment more objective by using a simulator may help to improve students’ adjusting skills in respect to speed, force and displacement of the thoracic spine. Evaluating a learned skill in an objective manner may allow better comparison with other students and tutors and possibly improve learning outcomes.

Increased spinal morbidity among drivers is well-documented and its pathomechanism has been objectively verified elsewhere by the authors. This study aims to explore the effects of chiropractic intervention in symptomatic drivers, assess the benefits to the driver and the transport company. A group of 22 symptomatic bus drivers were treated for various spinal complaints, following which their improvement, recovery and satisfaction were measured through a telephone survey. Analysis of the changes in the number of spine-related sick days, together with its financial benefits to their employer, was performed. The design was a retrospective two-tailed hypothesis testing of variances, using a single cohort of 22 symptomatic bus drivers. The independent variable was the driver's spinal complaint and the dependent variables an independent questionnaire and company's sick days record. Twenty-two symptomatic drivers approached the clinic, most of them with multiple spinal complaints of insidious onset and well-established chronicity. At the end of the treatment programme, drivers reported 84.3% improvement and 91.6% overall satisfaction. Average spinal absenteeism within the same group compared to previous year had dropped from 1.55 sick days per employee for 6 months down to 0.16. This trend achieved 95% significance in a paired t-test of variances. Chiropractic intervention within the work place for this population shows positive effects in terms of employee satisfaction, resolution of symptoms and cost effectiveness for the company involved.

Objective. Measure the effects of cervical extensor muscle isometric contraction on cervical surface electromyographic spectral shift and balance in healthy subjects. Design. Experimental within-subject design. Background. Postural instability can be induced by mechanically stimulating cervical muscle spindles. Postural changes are also observed in individuals who suffer from chronic neck pain or whiplash injury. Furthermore these subjects appear to experience neck musculature fatigue more quickly, which in turn not only affects the neck function but also seems to affect the balance in a standing posture. Methods. Using a force platform, balance was measured, in 10 blindfolded college students before and after isometric voluntary contraction in neck extension at 5% and 25% maximum voluntary isometric contraction for a period of 5, 10 and 15 min. Paired posturographic data were analysed for differences. Control measurements were performed on the same subjects by measuring balance before and after subjects sitting quietly for 5, 10 and 15 min without performing isometric contraction. Results. The results indicate that a 25% maximal isometric contraction of the neck extensors for 10 and 15 min duration produced significant changes in some posturographic parameters in young healthy males. Furthermore, this contraction also produced a significant cervical muscle electromyography median frequency spectrum shift of the lower frequencies. Conclusions. Balance was affected by 15 min of 25% maximal isometric contraction of the extensor cervical muscles. Posturographic parameters affected are similar to parameters observed in subjects that have suffered a whiplash injury.Relevance This study contributes to our understanding of functional aspects of cervical muscle fatigue. The similarity of results with other studies performed on subjects suffering from chronic neck pain and from whiplash injuries may suggest a similar cause for loss of postural control. Ultimately, this may help us in developing objective evaluation procedures for subjects suffering from neck complaints.

OBJECTIVE:To perform three-dimensional (3-D) manual contact force measurements of chiropractic adjustments at the patient-chiropractor interface.METHODS:A new hand/palm-held computerized 3-D force measuring system was used to collect 3-D force data at the doctor-patient interface (direct measurement) during cervical, thoracic, and sacroiliac adjustments by 2 chiropractors on 10 healthy subjects.RESULTS:3-D components of force were significantly greater than matching 1-dimensional (1-D) perpendicular force components, which have been the standard in direct measurement up until now. As well, 3-D components of force were significantly different between adjustment levels, suggesting different dynamics (kinetics) of adjustment techniques. Force magnitudes and statistically significant differences between loading rates and adjustment levels fit in the existing body of knowledge of chiropractic adjustment forces.CONCLUSION:To our knowledge, this is the first study which presents 3-D force-time histories of chiropractic adjustments recorded at the doctor-subject interface. Direct 3-D contact force data seem to have the potential to contribute to chiropractic research because of a more complete description of this biomechanical aspect of daily practice. Results can be used to study novice and experienced chiropractors' techniques and permit the development of training and evaluation protocols in teaching institutions.

The presence of movement at the SI joint has been increasingly investigated and discussed. Even though it has been contested in the past, the presence of movement at this articulation is now accepted. Since this joint must be relatively mobile, it is now considered that abnormal movement might be related to low back pain. Biomechanical models have been developed recently in order to better understand the relationship between SI joints and low back pain. It appears that the sacrum mobility control might necessitate the action of pelvic girdle muscles. The erector spinae, gluteus maximus, biceps femoris and latissimus dorsi muscles would produce moments necessary to lock the SI joint via the thoraco-lumbar fascia. This mechanism would increase the compressive forces on the joints surfaces and provide greater stability to and a more efficient load transfer from the spine to the lower extremity. Therefore the aim of this study is to determine the effect of increased tension of the thoraco-lumbar fascia and hip extension muscles on sacrum mobility. Ten male, weight-lifter subjects, aged between 18 and 25 participated in this study. A load displacement apparatus was developed in our laboratory. The subject is placed prone on a horizontal patient subject board or on a 30° triangular shaped board in order to produce tension on the thoraco-lumbar fascia. A total force of 250 N in 50 N increments is applied for every experimental situation. An isometric contraction of hip extensors of more than 80% of maximal muscle force is produced in each experimental condition. Results demonstrate that the overall force/displacement ratio obtained in this study is inferior to the data obtained by Miller et al. (1987) but similar to Brunner et al. (1991) and Vleeming et al. (1992b) in cadaveric specimens. Generally, the movement range of motion increases significantly (p < 0.001) in relation to the level of force applied. In our weight-lifters, hip contraction reduced sacrum mobility significantly (p < 0.001). Furthermore, the efficiency of the hip extensors in reducing the movement is still significant at 250 N. Our results indicate that the thoraco-lumbar fascia does not seem to participate in the locking of the SI joint, although other biomechanical variables must be evaluated before concluding on its implication. This study has demonstrated the efficiency of the experimental in vivo SI locking mechanism of the SI articulation.

INTRODUCTION: The presence of movement at the SI joint has been increasingly investigated and discussed in the past, and even though it has been contested, the presence of movement at this articulation is now accepted. Furthermore, it has been shown that abnormal motion at the SI modifies performance in weightlifters. To better understand the relationship between SI joints and function, models were developed: The Erector spinae, Gluteus maximus, Biceps femoris, and Latissimus dorsi muscles form a kinetic chain permitting load transfer via the different layers of the thoracolumbar fascia. This mechanism is thought to increase the compressive forces, much as a pelvic belt might do, on the SI joint surfaces and provide greater pelvic stability during activity. We challenged this concept by 1) evaluating the capacity of the hip extensors to lock the SI; 2) inducing tension in the thoracolumbar fascia by placing the subjects in a hip flexion position. METHODS: 10 experienced weight lifters aged between 18 and 25 years old took part in the study. Subjects were first placed prone on a flat surface and again on a triangular support structure producing 30o hip flexion. A previously described loaddisplacement apparatus was used to apply a total of 250 N in 50 N increments on S1 and then on S5. The loads were applied 1) with muscles relaxed and at a minimum of 80 % maximal voluntary isometric contraction of the hip extensors. RESULTS: Generally, the range of motion increased significantly as the load applied increased. There was a significant difference in the results between movement in nutation and contra-nutation (p<0.05). MVC of hip extensors reduced the sacrum mobility significantly (p<0.001) in both positions. Furthermore, the locking efficiency was still significant at loads of 250 N. On average, the MVC reduced the movement by 41%, and there was no difference in the efficiency in relation to position. There was no significant difference between the sacrum movement with the patient in a neutral or flexed position for either nutation or contra-nutation and this tendency was not influenced by the different loads applied. CONCLUSION: In our experiment, at 30 o of hip flexion, the thoraco-lumbar fascia does not contribute to the SI locking mechanism. This study has demonstrated that MVC of the hip extensors in weight lifters significantly limits movements of the sacrum. Medical staff, trainers and coaches involved in weight lifting and other physical activities are encouraged to consider specific hip extensor exercises with the objective of increasing the SI locking and potentially preventing injuries. Finally, muscular synergy studies in symptomatic athletes may in some instances indicate an inefficient SI locking mechanism. These studies could provide interesting approaches to the treatment of individuals suffering from SI hypermobility.

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Health literacy (HL) and the overall ability of patients to seek, understand, and apply health information play an important role in the management of chronic pain conditions. Awareness of how patients' HL skills influence their pain experience and how their ability to understand the treatment regimen and to manage chronic pain may allow physicians to adjust clinical treatment accordingly. Despite the prevalence and the substantial economic impact of chronic low back pain (LBP), little is known about the relationship between HL and the treatment and management of this common disease entity.The purpose of this systematic review of published research was to examine the importance and the implications of HL in the treatment and management of LBP.A literature search was performed in Web of Science, PubMed, Cumulative Index to Nursing and Allied Health Literature, and PsychInfo using medical subject heading (MeSH) terms related to LBP, HL, and patient education, which yielded only three studies that directly addressed HL among patients suffering from LBP.We identified only a limited number of studies that focused specifically on HL in the LBP population that were included in this review. The majority of studies excluded from this review focused on patient levels of educational attainment and patient education programs without addressing patients' HL levels and their impact on adherence to educational programs, self-care management, and rehabilitation, among other factors. The three studies that are critically reviewed in this review either use a direct measure of HL or make an effort to address HL in their programs. All three studies emphasize the importance of considering the HL of patients in the treatment and management of LBP.Building on these studies and the narrative review of other relevant literature, we identified significant gaps in current research addressing HL in the treatment and management of LBP. We developed recommendations for future research based on an assessment of strengths and limitations of available evidence-based studies.

BACKGROUND AND OBJECTIVE. In today’s youth hockey leagues, the participation of an individual is based on the chronologic age without regard to the children's variations in development and maturity. Although it is currently accepted that the overall strength and growth of children increases linearly throughout childhood until puberty, the individual body parts growth do not develop at the same rate. The object of this project was to evaluate pelvic girdle resistance of youth hockey players in relation to leg length. METHOD. Nine hundred (n=900) hockey players aged 6 to 16 participated in the study. First, a 14 points physical examination was done on all subjects. Finally the Milgram test (modified bilateral leg raise) was performed. This procedure represents a good and easily performed test of hip flexors resistance and permits possible detection of thecal pathology. Incidence of positive Milgram test is presented and a Chi square statistical test is used. RESULTS. The results indicate that in our subjects, the youngest and oldest players had the lowest percentage of positive findings on the Milgram test; 6 years old: 5%, 16 years old 7.14%. The 10, 11 and 12 year old groups had a mean value of 47.22% positive Milgram tests. From all the 257 subjects with positive Milgram test only 2 individuals demonstrated possible thecal pathologies after the fourteen steps examination was performed. The Chisquare (x*) statistical test indicates that the difference between the observed frequency and between the theoretical frequency is significant (X2 = 117,081, df = 10, Q < .OOl). CONCLUSIONS. It appears from this study that almost 50% of children in the 10, 11 and 12 year old have difficulty in performing a simple hip flexing resistance exercise. This situation may be secondary to an uneven rate of growth of the lower limbs versus torso, therefore increasing the leg moment arms, thus increasing load and brending moments on the pelvic structures. . These results may explain the observed difficulty some of these hockey players experience in performing specific skills demanding high pelvic and hip flexors strength and resistance. Researchers are encourage to pursue biomechanical investigation f limb length ratio and their specific effects on axial structures and development.