Effects of cognitive load on the amount and temporal structure of postural sway variability in stroke survivors.

This study aimed to investigate the variability in postural sway patterns during quiet standing in stroke survivors. The postural sway was measured in 19 stroke survivors, as well as 19 healthy demographically matched participants, at 3 levels of postural difficulty (rigid surface with closed and open eyes, and foam surface with closed eyes), and 3 levels of cognitive difficulty (without a cognitive task, easy and difficult cognitive tasks). Both linear analyses (the amount of postural sway variability, including the standard deviation of the COP velocity in both the anteroposterior (AP) and mediolateral (ML) directions), as well as non-linear analyses [the temporal structure of the COP variability, including % Recurrence, % Determinism, Shannon Entropy, Trend and the maximum diagonal line (D max)] were employed. The results revealed that the amount of variability of the postural sway of stroke survivors was significantly greater than that of healthy participants, along both the ML and AP directions, with the highest obtained during standing on foam with closed eyes. All measures of the temporal structure of the COP variability were significantly greater in stroke survivors, as compared to the control group, along the ML direction, but not along the AP direction. The cognitive error was significantly higher during difficult cognitive tasks, although it was neither affected by postural difficulty nor by group. The different results obtained for the amount and temporal structure of the COP variability in the AP and ML directions shed light on the intricate mechanisms employed by the CNS in post-stroke balance control, and suggest that effective rehabilitative and therapeutic strategies should be patient-specific, taking both the environment/surface as well as the specific protocols into consideration.

The effect of combined mechanism ankle support on postural control of patients with chronic ankle instability.

BACKGROUND: Chronic ankle instability is associated with neuromechanical changes and poor postural stability. Despite variety of mechanisms of foot and ankle orthoses, almost none apply comprehensive mechanisms to improve postural control in all subgroups of chronic ankle instability patients. OBJECTIVES: The purpose of this study was to investigate the effect of an ankle support implementing combined mechanisms to improve postural control in chronic ankle instability patients. STUDY DESIGN: Cross-sectional study. METHODS: An ankle support with combined mechanism was designed based on most effective action mechanisms of foot and ankle orthoses. The effect of this orthosis on postural control was evaluated in 20 participants with chronic ankle instability and 20 matched healthy participants. The single-limb stance balance test was measured in both groups with and without the new orthosis using a force platform. RESULTS: The results showed that application of combined mechanism ankle support significantly improved all postural sway parameters in chronic ankle instability patients. There were no differences in means of investigated parameters with and without the orthosis in the healthy group. No statistically significant differences were found in postural sway between chronic ankle instability patients and healthy participants after applying the combined mechanism ankle support. CONCLUSION: The combined mechanism ankle support is effective in improving static postural control of chronic ankle instability patients to close to the postural sway of healthy individual. the orthosis had no adverse effects on balance performance of healthy individuals. Clinical relevance Application of the combined mechanism ankle support for patients with chronic ankle instability is effective in improving static balance. This may be helpful in reduction of recurrence of ankle sprain although further research about dynamic conditions is needed.

The effect of orthotic devices on knee adduction moment, pain and function in medial compartment knee osteoarthritis: a literature review.

Background Knee braces and foot orthoses are commonly used to improve knee adduction moment, pain and function in subjects with knee osteoarthritis (OA). However, no literature review has been performed to compare the effects of foot orthoses and knee braces in this group of patients. Purpose The aim of this review was to evaluate the effects of foot orthoses and knee braces on knee adduction moment, pain and function in individuals with knee OA. Study design Literature review. Method The search strategy was based on the Population Intervention Comparison Outcome method. A search was performed in PubMed, Science Direct, Google Scholar and ISI web of knowledge databases using the PRISMA method and based on selected keywords. Thirty-one related articles were selected for final evaluation. Results The results of the analysis of these studies demonstrated that orthotic devices reduce knee adduction moment and also improve pain and function in individuals with knee OA. Conclusion Foot orthoses may be more effective in improving pain and function in subjects with knee OA. Both knee braces and foot orthoses reduce the knee adduction moment in knee OA and consequently patients typically do not need to use knee braces for a long period of time. Also, foot orthoses and knee braces may be more effective for medial compartment knee OA patients due to the fact that this treatment helps improve pain and function. Implications for Rehabilitation Knee braces and foot orthoses are commonly used for improving knee adduction moment, pain and function in subjects with knee osteoarthritis (OA). Orthotic devices can reduce knee adduction moment, pain and improve function in knee OA. The combined use of a knee braces and foot orthoses can provide more improvement in knee adduction moment, reduced pain and increased function.

The effects of a short-term memory task on postural control of stroke patients.

BACKGROUND: Many studies have been conducted on the changes in the balance capabilities of stroke patients. However, results regarding the effects of dual-task activities on postural control in these patients have been variable. OBJECTIVE: To evaluate the effects of a short-term memory task on the sway characteristics of stroke patients. METHOD: Center of pressure (COP) fluctuations were measured in three levels of postural difficulty (rigid surface with closed and open eyes and foam surface with closed eyes), as well as two levels of cognitive difficulty (easy and difficult). COP parameters included mean velocity, standard deviation of velocity in both medial-lateral (M.L) and anterior-posterior (A.P) directions, total phase plane portrait, area. Nineteen stroke patients and 19 gender, age, height, and weight matching healthy volunteers participated in this study. RESULTS: Our findings indicate that mean velocity (F = 14.21, P = 0.001), standard deviation of velocity in both M.L (F = 17.50, P = 0.000) and A.P (F = 11.03, P = 0.002) directions, total phase plane portrait (F = 44.12, P = 0.001), and area (F = 13.95, P = 0.01) of center of pressure of patients were statistically greater than normal subjects, while significant interaction of group × postural difficulty and postural × cognitive difficulty were observed for all parameters of postural sway. CONCLUSIONS: Different measures of postural sway showed complex response to postural and cognitive difficulties between stroke patients and normals. Cognitive error was not affected by the main effects of group and postural difficulty, while greatly increased at more difficult cognitive task (F = 75.73, P = 0.000).

Clinical effectiveness of kinesiological taping on pain and pain-free shoulder range of motion in patients with shoulder impingement syndrome: a randomized, double blinded, placebo-controlled trial.

BACKGROUND: Kinesiological taping (KT) is commonly used to improve symptoms associated with musculoskeletal disorders. However, review of the literature revealed minimal evidence to support the use of KT in treatment of shoulder disorders and controversy exists regarding the effect of KT in patients with shoulder impingement syndrome (SIS). OBJECTIVE: The purpose of this study was to investigate the effect of KT on pain intensity during movement, pain experienced during the night (nocturnal pain), and pain-free shoulder range of motion (ROM) immediately after taping, after three days and after one week, in patients with SIS. DESIGN: Randomized, Double blinded, Placebo-controlled design. PARTICIPANTS: A total of 30 patients with SIS participated in this study. Patients were assigned randomly to a control (N = 15) and an experimental group (N = 15). METHODS: The patients in the experimental group received a standardized therapeutic KT. The standardized, placebo neutral KT was applied for control group. KT was applied two times with a three day interval, remaining on during the 3 day interval. Both groups followed the same procedures. Pain-free active ROM during shoulder abduction, flexion, and elevation in the scapular plane was measured. Visual analogue scale (VAS) for pain intensity during movement or nocturnal pain and was assessed at baseline, immediately after KT, after three days, and one week after KT. RESULTS: The result of repeated measures ANOVA showed a significant change in pain level during movement, nocturnal pain, and pain-free ROM (p = 0.000) after KT in the experimental group. In the ANCOVA, controlling for pre-test scores, change in pain level at movement (p = 0.009) and nocturnal pain (p = 0.04) immediately after KT was significantly greater in the experimental group than in control group. There was no significant difference in ROM measures (p > 0.05) between groups immediately after KT. No significant differences were found between the two groups in the after one week measurements of pain intensity and shoulder ROM. CONCLUSION: The KT produces an immediate improvement in the pain intensity at movement and nocturnal pain in patients with SIS. LEVEL OF EVIDENCE: 1.

Trunk muscles strength and endurance in chronic low back pain patients with and without clinical instability.

OBJECTIVES: Previous research has shown inconsistent findings regarding muscle endurance in chronic low back pain (CLBP). Questions also remain about muscle endurance in patients with clinical instability. The aim of this study was to investigate trunk muscles strength and endurance in CLBP patients with and without clinical instability. METHODS: 32 CLBP patients (15 with and 17 without clinical instability) and 39 matched healthy subjects participated in this study. The standing extension test was performed to assess the strength and endurance of the lumbar extensors while recording their electromyographic activity. The patients' disability was evaluated using the Oswestry and Roland-Morris Disability Questionnaires. RESULTS: Patients with clinical instability showed lower maximal voluntary exertion (MVE) and higher time to fatigue (TTF) compared to healthy subjects (P=0.000 and P=0.008, respectively) and patients without instability (P=0.002 and P=0.02, respectively). There was no difference in these variables between patients without instability and healthy controls. A negative relationship between MVE and TTF and a positive correlation between disability and pain intensity were seen. CONCLUSION: Strength training of trunk extensor muscles can be considered as part of the treatment protocol for CLBP patients with clinical instability. Although patients without instability suffered from pain or disability, they showed more similarity to healthy subjects in terms of trunk muscles strength and endurance.

Effect of dual-tasking on postural control in subjects with nonspecific low back pain.

STUDY DESIGN: Three factors mixed-design with 1 between-subject and 2 within-subject factors. OBJECTIVE: To compare the main effects and interactions of postural and cognitive difficulty on quiet stance between subjects with and without nonspecific low back pain (LBP). SUMMARY OF BACKGROUND DATA: The interference between postural control and cognitive tasks depends on factors such as sensorimotor/cognitive integrity. Changes in peripheral sensory and muscular systems as well as cognitive processes have been observed in LBP patients. It was hypothesized that the effect of cognitive task on postural performance might be different in subjects with nonspecific LBP as compared with healthy individuals. To the authors' knowledge this has not been investigated before. METHODS: Postural stability was measured by center of pressure parameters while nonspecific LBP (n = 22) and healthy (n = 22) subjects randomly performed quiet standing task with 3 levels of difficulty (rigid-surface eyes open, rigid-surface eyes-closed, and foam-surface eyes-closed) in isolation or concurrently with an easy or difficult digits backward cognitive task. RESULTS: Subjects with nonspecific LBP had less postural sway than healthy subjects, while postural sway decreased with increase in the level of cognitive difficulty. Nonspecific LBP and healthy subjects had larger postural sway at more difficult sensory conditions such as rigid-surface eyes-closed and foam-surface eyes-closed. The response to dual-tasking was not significantly different between the 2 groups. CONCLUSION: The dual-tasking did not change the postural performance of nonspecific LBP subjects with low level of pain and disability differently compared to healthy subjects.

Test-retest reliability [corrected] of center of pressure measures of postural stability during quiet standing in a group with musculoskeletal disorders consisting of low back pain, anterior cruciate ligament injury and functional ankle instability.

Reliability is a population-specific property, but to the authors' knowledge there has been no study to determine the test-retest reliability of the postural stability measures such as center of pressure (COP) measures in the population of patients with musculoskeletal disorders (MSDs), while their clinical applications have been presented in literature. So, 33 patients with low back pain (LBP), anterior cruciate ligament (ACL) injury and functional ankle instability (FAI) randomly completed postural measurements with three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed) in two sessions. COP data were used to calculate standard deviation of amplitude, standard deviation of velocity, phase plane portrait, mean total velocity and area (95% confidence ellipse). Relative reliability of these measures was assessed using intraclass correlation coefficient (ICC) and absolute reliability using standard error of measurement (SEM) and coefficient of variation (CV). Also, minimal metrically detectable change (MMDC) was calculated to quantify intervention effects. Among different COP parameters, mean total velocity in all conditions of postural difficulty showed high to very high reliability, with ICC range of 0.74-0.91, SEM range of 0.09-0.40cm/s, CV range of 5.31-8.29% and MMDC range of 0.19-0.79cm/s. Phase plane portrait in anteroposterior-mediolateral (AP-ML) and ML direction were other best parameters with respect to the level of reliability. Mean total velocity and phase plane portrait parameters are suggested as good candidates to use for quantification and assessment of balance performance and identifying those with MSDs.

Sensitivity, specificity and predictive value of the clinical trunk muscle endurance tests in low back pain.

OBJECTIVE: To describe the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of five clinical tests used to measure trunk muscle endurance in low back pain. DESIGN: A cross-sectional non-experimental design. SETTING: Orthopaedic and physical therapy departments of four hospitals and outpatient physical therapy clinics, Tehran, Iran. SUBJECTS: Convenience sample of 200 subjects participated in this study. Subjects were categorized into four groups: men without low back pain (N = 50, mean (SD) age = 38 (12) years), women without low back pain (N = 50, mean (SD) age = 43 (11) years), men with low back pain (N = 50, mean (SD) age = 39 (12) years) and women with low back pain (N = 50, mean (SD) age = 43 (12) years). MAIN MEASURES: Five clinical static endurance tests of trunk muscles such as: Sorensen test, prone isometric chest raise test, prone double straight-leg raise test, supine isometric chest raise test and supine double straight-leg raise test were measured in each group. RESULTS: The result of receiver operating characteristics (ROC) curve analysis revealed that in a separate analysis of data for men and women, among all tests, the prone double straight-leg raise test had the highest sensitivity, specificity and predictive value in low back pain compared with other performed tests. CONCLUSIONS: It seems that the prone double straight-leg raise test has more sensitivity, specificity and predictive value in low back pain than other tests and could be used as a useful clinical method for testing the spinal muscle endurance to predict the probability of the occurrence of low back pain.

Changes in postural stability with fatigue of lower extremity frontal and sagittal plane movers.

The purpose of this study was to quantify changes in postural stability with fatigue of the frontal and sagittal movers of the lower extremities. There were four test sessions, with a randomized order assigned according to the muscles tested and the plane of motion. Subjects were 20 healthy men (age: 22.6+/-2.4 years, height: 173.7+/-3.6 cm, weight: 63.3+/-7.9 kg). During each session, one set of muscle groups was fatigued using isokinetic contractions: ankle plantar/dorsi flexors, ankle evertor/invertors, hip flexor/extensors or hip abductor/adductors. The Biodex Stability System was used to assess anterior/posterior and medial/lateral stability before and after muscle fatigue. Repeated measures ANOVAs revealed that fatigue was associated with a significant increase in all stability indices. Fatigue of the hip movers, whether in the frontal or sagittal planes, led to greater increments in stability indices than fatigue of the ankle musculature. Fatigue of the frontal movers resulted in greater increases in the medial/lateral stability index compared to fatigue of the sagittal movers. In conclusion, fatigue of proximal lower extremity muscles affects postural stability and fatigue of the frontal movers is associated with postural instability in the frontal plane.