Ageing of internal models: from a continuous to an intermittent proprioceptive control of movement

To control the sensory–motor system, internal models mimic the transformations between motor commands and sensory signals. The present study proposed to assess the effects of physiological adult ageing on the proprioceptive control of movement and the related internal models. To this aim, one group of young adults and one group of older adults performed an ankle contralateral concurrent matching task in two speed conditions (self-selected and fast). Error, temporal and kinematic variables were used to assess the matching performance. The results demonstrated that older adults used a different mode of control as compared to the young adults and suggested that the internal models of proprioceptive control were altered with ageing. Behavioural expressions of these alterations were dependent upon the considered condition of speed. In the self-selected speed condition, this alteration was expressed through an increased number of corrective sub-movements in older adults as compared to their young peers. This strategy enabled them to reach a level of end-point performance comparable to the young adults' performance. In the fast speed condition, older adults were no more able to compensate for their impaired internal models through additional corrective sub-movements and therefore decreased their proprioceptive control performance. These results provided the basis for a model of proprioceptive control of movement integrating the internal models theory and the continuous and intermittent modes of control. This study also suggested that motor control was affected by the frailty syndrome, i.e. a decreased resistance to stressors, which characterises older adults.     

Effects of shoe sole thickness on joint position sense

The objective of this study was to determine the effects of shoe sole thickness on joint position sense in the sagittal and frontal plane by determining the estimate angle error. Joint position sense was measured by manipulating angle and direction of a slope surface board (30 cm×30 cm×1.5 cm) to perform the movements of dorsiflexion, plantar flexion, inversion and eversion. Sandwiching wooden wedges with pre-determined angles between 0 and 25° between the slope surface boards made the slope surface angles. Twenty healthy college male students were asked to estimate the angle and direction of movements under each of the shod conditions while standing on the slope surface board. Estimate angle error was calculated for each movement under all shod conditions. For all shod conditions, estimate angle error was the greatest for plantar flexion and inversion compared to dorsiflexion and eversion. Independent of shod condition, subjects had the most difficulty estimating plantar flexion and inversion movements.     

Analysis of electromyographic activity of ankle muscles on stable and unstable surfaces with eyes open and closed

Introduction

Proprioceptive exercises are performed on a daily basis in physiotherapy with the use of different unstable platforms in order to improve joint stability using the mechanical and sensory properties of ligaments, joint capsule and integrated activity of the muscles surrounding the joint. Changes in the myoelectrical characteristics of the muscles during activity can be identified using surface electromyography (EMG), which provides important information on the behavior of muscles submitted to different types of load.

Objectives

The aim of the present study was to analyze the electromyographic activity of the tibialis anterior, tibialis posterior, peroneus longus, gastrocnemius lateralis and gastrocnemius medialis on stable and unstable surfaces with eyes open and closed.

Methodology

Twenty-five active, healthy, male and female individuals were submitted to an anthropometric evaluation and a protocol involving warm up and the electromyographic assessment of muscle activity on different surfaces. The order of the data collection was chosen randomly by lots [on stable ground or unstable platforms (trampoline, balance platform, proprioceptive disk and proprioceptive board) with eyes open and on a trampoline, balance platform and stable ground with eyes closed]. The individuals remained balanced on these surfaces for 15 s with the knee at 30° flexion in order to provide greater instability.

Results

There was a significant increase (p < 0.05) in muscle activity on the unstable surfaces, with the exception of the trampoline, which did not achieve statistically significant differences in relation to the stable ground. The tibialis anterior and peroneus longus exhibited the greatest electromyographic activity on all surfaces. The proprioceptive tests performed with eyes closed exhibited significantly greater electromyographic activity than with eyes open.

Conclusion

Proprioceptive exercises on unstable surfaces generated a significant increase in electromyographic activity, especially with eyes closed, and are therefore a valuable resource in the sensory-motor rehabilitation of the ankle.     

Deficits in upper limb position sense of children with Spastic Hemiparetic Cerebral Palsy are distance-dependent

This study examined the arm position sense in children with Spastic Hemiparetic Cerebral Palsy (SHCP) and typically developing children (TD) by means of a contralateral matching task. This task required participants to match the position of one arm with the position of the other arm for different target distances and from different starting positions. Results showed that children with SHCP exhibited with both arms larger matching errors than the TD group, but only when the distance between the arms at the start of the movement was large. In addition, the difference in errors between the less-impaired and the impaired limb changed as a function of the distance in the SHCP group whereas no interlimb differences were found in the TD group. Finally, spasticity and restricted range of motion in children with SHCP were not related to the proportion of undershoot and size of absolute error. This suggests that SHCP could be associated with sensory problems in conjunction with their motor problems. In conclusion, the current study showed that accurate matching of the arms is greatly impaired in SHCP when compared to TD children, irrespective of which arm is used. Moreover, this deficit is particularly present for large movement amplitudes.     

A comparison of the efficacy of textured insoles on balance performance in older people with versus without plantar callosities

BackgroundTextured insoles have been suggested to enhance foot sensation, which contributes to controlling upright balance. However, the interaction between plantar callosity and the textured surface has not been studied.Research questionFirstly, to compare the efficacy of textured insoles on balance performance and foot position sense between two groups of older people: one group had plantar callosity, and the other did not. Secondly, to investigate the efficacy of textured insoles within each study group.MethodsThirty older people with a history of falls (15 with plantar callosity and 15 without callosity) participated in this study. All participants underwent assessments of postural sway on a force plate, joint position sensation of the ankle with a slope box, and mobility using the "Timed Up and Go" test under three insole surface conditions: 1) smooth (control), 2) placebo and 3) textured surface. Two-way analyses of variance were used to compare the outcomes of the two groups and three conditions.ResultsOlder people with plantar callosity had worse ankle joint position sense and slower antero-posterior and mediolateral postural sway velocity than their peers who did not have plantar callosity. The textured insoles improved ankle joint position sense and mobility regardless of callus status in the plantar surface of older peoples’ feet. The insole-callosity interaction was not significant for any study outcome.SignificanceTextured insoles could be beneficial to older people with and without callosity as they have shown immediate improvements in ankle joint position sense and mobility.     

The effects of cryotherapy on athletes’ muscle strength,flexibility, and neuromuscular control: A systematic review of the literature

PurposeThis review aimed to investigate the effects of cryotherapy on the functional capacity parameters of athletes, such as muscular strength, flexibility, neuromuscular control, and balance.MethodsA computerized search of EBSCO Host databases, Proquest, Medline, SportDiscus, CinahlPlus, Health Source Nursing/Academic Edition, Academic Search Complete, and GoogleScholar databases was performed to identify clinical trials with a focus on cryotherapy applications in sport. Thekeywords used were “cryotherapy,” “sports,”“strength,”“flexibility,” and “proprioception.”Study selectionRandomized control trials and randomized crossover studies of healthy athletes were included in this review. The methodological quality of the studies was assessed by the validation criteria given by Furlan et al (2009).ResultsA total of 50 randomized controlled trials (RCTs) and randomized crossover studies met the above criteria and were included in the final analysis. The studies available indicate that there is no strong research evidence to suggest that cryotherapy can definitely influence joint strength and neuromuscular control. The only positive effect of cryotherapy appears to be an improvement in joint flexibility.ConclusionsLimited and equivocal evidence is available to address the effect of cryotherapy on muscular function. The only evidence-based positive impact after the applications of cryotherapy is improved joint flexibility. Despite the extensive use of cryotherapy in sports, further research is needed to document the actual effects of cryotherapy applications on athletes' functional performance and rehabilitation parameters.     

Seven cervical sensorimotor control tests measure different skills in individuals with chronic idiopathic neck pain

BackgroundSensorimotor control is commonly reported in neck pain research and rapidly gaining interest in clinical practice. Joint position error (conventional and torsion), postural balance, subjective visual vertical, head tilt response, The Fly®, smooth pursuit neck torsion and head steadiness are tests that have been reported to assess cervical sensorimotor control. However, it is unknown whether clinicians could use one test, or a test battery, to appropriately assess cervical sensorimotor control and improve efficiency. Our main research question is: Do seven cervical sensorimotor control tests measure unique or similar characteristics of sensorimotor control in individuals with chronic idiopathic neck pain?MethodsPrinciple components factor analysis. Data from seven cervical sensorimotor control tests of 50 participants with chronic idiopathic neck pain were included. Individual factors, potentially related to sensorimotor control, were determined by Eigen values >1.00 and inspection of a loading plot. Items with loadings ≥0.40 were considered satisfactory for inclusion in a factor.ResultsAll cervical sensorimotor control tests were found to measure unique skills. Four factors were isolated with two, postural balance and head steadiness, accounting for most of the variance across tests. The remaining two factors, continuous movement accuracy and perceived verticality, contributed less to the observed variance.ConclusionPostural balance and head steadiness were the major underlying factors explaining cervical sensorimotor control in the current sample. However, our results imply that all seven tests are independent and measure different skills. It is not possible to recommend a test battery for clinical practice, as all tests measure unique skills which appear to be independent of each other.     

Center of pressure position in the touches of the star excursion balance test in healthy individuals

BackgroundThe Star Excursion Balance Test (SEBT) is a clinical test that aims to assess postural control. Its interpretation is related to the understanding of the motor specificities required. Adjustments must be made to the center of pressure (COP) to maintain balance during testing movements. Comprehend the specifics of these adjustments for each direction can allow the development of more suitable exercises for balance training. The aim was to compare the positions of the COP on the different directions of the SEBT and correlate the reachs obtained in the SEBT with the distances from the COP to the borders of the base of support (BOS).MethodsSixteen healthy subjects participated in the study. Measurements were made by performing the SEBT over the force platform. The Kruskal-Wallis test followed by Bonferroni's post hoc test was used to compare directions. The Pearson correlation test was used to check the correlation of parametric variables and Spearman correlation test for the nonparametric ones.ResultsThe position of the COP at the touch differs from the anterior direction to the other directions of the SEBT and the performance in this direction is correlated with the proximity of the COP to the anterior limit of the support base. The performances in the other directions did not correlate with the COP position.ConclusionThe requirements of the compensation mechanisms for postural control are different between the directions of the SEBT.     

Test-retest reliability of upper-limb proprioception and balance tests in older nursing home residents

AimTo examine the test-retest reliability of two upper-limb proprioception tests (Weight Detection Test, or WDT, and Arm Ruler Positioning Test, or ARPT) and two balance tests (Functional Reach Test, or FRT, and Timed Up and Go test, or TUG) in older nursing home residents.MethodsFifty-three nursing home residents (85.9 ± 3.9 years) participated in this study. Outcome measures were assessed on two occasions, 10–14 days apart. The same rater administered all tests. The relative reliability was estimated using the intraclass correlation coefficients (ICCs) with a two-way mixed-effects model. The absolute reliability was analyzed using the standard error of the mean (SEM) to estimate the minimal detectable change (MDC) at the 95 % confidence level. Systematic bias was studied using the paired-samples t-test or the Wilcoxon signed-rank test.ResultsThe WDT (ICC = 0.84), ARPT (ICC = 0.87) and FRT (ICC = 0.85) had good relative reliability, and the TUG (ICC = 0.99) had excellent reliability. Our results suggest acceptable measurement precision: the SEMs were equal to 1.0 points, and 0.3 cm, 1.5 cm, and 0.5 s for the WDT, ARPT, FRT, and TUG, respectively. The mean difference between sessions was 0.3 points (1.4 %; w=-1.37, p = 0.17) in the WDT, 0.1 cm (-0.74 %; t = 0.41, p = 0.68) in the ARPT, 0.1 cm (0.45 %; w=-0.33, p = 0.74) in the FRT, and 0.2 s (1.37 %; w=-2.28, p = 0.02) in the TUG.ConclusionsThis study showed that the four field-usable motor tests had good to excellent test-retest reliability and had acceptable measurement precision in older nursing home residents. These tests could be valuable clinical tools for assessing proprioception and balance in nursing home residents.     

A novel staged wrist sensorimotor rehabilitation program for a patient with triangular fibrocartilage complex injury: A case report

Study DesignCase report.IntroductionStudies have highlighted the sensory innervations and stabilizing role of forearm muscles on wrist joint and implications to wrist sensorimotor rehabilitation. This case explored the novel incorporation of dart-throwing motion and proprioceptive neuromuscular facilitation in wrist sensorimotor rehabilitation.Purpose of the StudyTo describe and evaluate a staged wrist sensorimotor rehabilitation program for a patient with triangular fibrocartilage complex (TFCC) injury.MethodsThe patient participated in the staged program for 9 sessions over a 3-month period. Treatment involved neuromuscular strengthening at the wrist and movement normalization of the upper extremity. Outcome measures were grip strength, visual analog scale, joint position sense, Quick Disabilities of the Arm, Shoulder and Hand, and patient-rated wrist evaluation.ResultsThe patient showed improvement in all outcome measures. Most outcomes exceeded the established minimal clinically important difference values.DiscussionThe results suggest that dart-throwing motion and proprioceptive neuromuscular facilitation are beneficial in rehabilitation of TFCC injury.ConclusionsThis is the first study that incorporated dart-throwing motion and proprioceptive neuromuscular facilitation in the sensorimotor rehabilitation of TFCC injury and yielded promising results. There is a need to further evaluate the program in prospective randomized controlled trial recruiting a larger group of patients with TFCC injury.