Test–retest reliability of muscle vibration effects on postural sway

The effect of alterations in the processing of proprioceptive signals, on postural control, has been studied using muscle vibration effects. However, reliability and agreement of muscle vibration have still to be addressed.This study aimed to assess intra- and interday reliability and agreement of vibration effects of lumbar paraspinal and triceps surae muscles in a non-selected sample of 20 subjects, standing on solid surface and on foam. We used mean position and velocity of Centre of Pressure (CoP), during and after vibration to quantify the effect of muscle vibration. We also calculated the ratio of vibration effects on the lumbar paraspinal and triceps surae muscles (proprioceptive weighting).Displacement of the CoP during vibration showed good reliability (ICCs > 0.6), and proprioceptive weighting of displacement fair to good reliability (0.52–0.73). Agreement measures were poor, with most CV's ranging between 18% and 36%. Change in CoP velocity appeared not to be reliable. Balance recovery, when based on CoP position and calculated a short period after cessation of vibration, showed good reliability. According to this study, displacement during vibration, proprioceptive weighting and selected recovery variables are the most reliable indicators of the response to muscle vibration.     

Chronic ankle instability affects learning rate during repeated proprioception testing

Objectives1. To determine whether individuals with chronic ankle instability (CAI) have lower proprioception sensitivity scores from a test on the Active Movement Extent Discrimination Apparatus (AMEDA). 2. To determine whether individuals with CAI can improve proprioception sensitivity scores with repeated active movement testing using the AMEDA. 3. To assess the test-retest reliability of the AMEDA.DesignA cohort study comparing those with CAI or healthy ankles.SettingUniversity clinical laboratory.Participants61 healthy university students, 36 with CAI, 25 with stable ankles.Main outcome measuresA 2-way ANOVA was conducted to compare performance of CAI and stable ankle groups, over 3 test repetitions on the AMEDA. The reliability intra-class correlation coefficient (ICC) was obtained for test repetitions.ResultsThe scores improved in both groups when the AMEDA test was repeated (p = <0.001). The rates of improvement in proprioception test scores differed, with the CAI group showing a slower learning rate than the stable ankle group (p = 0.047). The ICC for the whole group across the three trials was 0.80 (95% CI = 0.69 to 0.87, p = <0.001).ConclusionsCAI participants improve their proprioception scores more slowly upon repeated AMEDA testing, suggesting differences in learning strategies.     

Effect of ankle taping on angle and force matching and strength of the plantar flexors

ObjectiveInvestigate the effect of ankle taping on plantar-flexion strength, angle matching and force matching.DesignSingle group, repeated measures.SettingLaboratory of an educational institution.ParticipantsTwenty uninjured females (22.9 ± 3.6 years).Main Outcome MeasuresTape was applied to the ankle using a conventional hindfoot technique. Angle and force matching, and plantar-flexor strength were assessed using the purpose built dual ankle dynamometer, and measures were taken prior to and following taping. Angle matching was assessed passively and actively at 10, 15 and 20° of plantar-flexion. Participants were required to match the angle of the reference leg with the contralateral leg. Force matching was assessed at 10° of plantar-flexion and participants matched the torque of the reference leg with the contralateral leg.ResultsTaping had no effect on absolute errors during active or passive angle matching. Regardless of taping, the ankle angle tested had a significant effect on passive angle matching (p < 0.001); subjects were most accurate at matching a plantar-flexion angle of 20°. Ankle taping had no effect on force matching. Taping significantly improved peak plantar-flexion strength by 20% (p = 0.028).ConclusionAnkle taping has little effect on contralateral force and angle matching, but it can enhance peak plantar-flexion strength.     

Altered postural control in anticipation of postural instability in persons with recurrent low back pain

Insight into the mechanisms of altered postural control in persons with low back pain (LBP) could lead to better interventions for patients with LBP. This study investigated (1) whether persons with recurrent LBP have an altered body inclination, and (2) whether anticipation of postural instability further alters body inclination. Thirty-three young healthy individuals and 56 young persons with recurrent LBP participated in this study. The upright standing posture was evaluated by means of two piezo-resistive electrogoniometers and a force platform for the conditions as follows: (1) quiet stance with and without vision, and (2) in anticipation of postural instability due to a ballistic arm movement or ankle muscle vibration. No differences in body inclination were observed when visual information was available between the two groups (P > 0.05). However, significant more forward inclination was seen in the persons with recurrent LBP when vision was occluded (+7.4%) and in anticipation of postural instability (+19%) (P < 0.05) compared to the healthy individuals. The results suggest that young persons with recurrent LBP have an altered body inclination that might be caused by anticipation of postural instability. The adopted forward inclined posture may potentially be a factor in the recurrence of LBP.     

Proprioceptive regulation of interlimb behavior: interference between passive movement and active coordination dynamics

The coordination of homolateral effectors (right arm/right leg) according to the in-phase or anti-phase mode was perturbed through passive movement of a third segment (left arm or left leg) imposed by the experimenter. The manipulated parameters of the passive segment were frequency and amplitude along with their degree of scaling. Results showed that passive movement degraded anti-phase patterns more than in-phase patterns. Furthermore, the anti-phase mode deteriorated profoundly during frequency manipulation, but scaling did not induce additional effects, whereas a linear association was observed between anti-phase deterioration and amplitude manipulation. Together, these data indicate that passive movement disturbed the coordination dynamics of an actively performed task. The fact that interference depended on the manipulated parameter suggests a distinction in the degree of intrusiveness of the irrelevant afferent information induced by the passive limb. It is concluded that sensory discrimination between irrelevant and relevant input is critical in performing a coordinated task adequately under perturbed conditions.     

Manipulation of extraocular muscle afference has no effect on higher order perceptual judgments

Observers perceive targets as farther while performing the Jendrassik Maneuver (JM) suggesting that eye position is registered as more divergent. We examined the effects of the JM perturbation in three studies of perceptual judgment that rely on accurate registration of absolute distance: size constancy, stereoscopic depth, and the magnitude of the Pulfrich illusion. The data showed no significant differences between the JM and control conditions. The lack of an effect may be due to the fact that vergence is not a perfect cue to distance. Furthermore, the relative contribution of extraocular muscle afference to registered eye position may be less significant for higher order perceptual judgments.     

The contribution of gravitational torques to limb position sense

Summary An experiment is reported which examined whether gravitational torque acting about a joint is used by the CNS in elbow joint angle matching. Subjects were required to match the joint angles of their two limbs while the external torques acting about each elbow were systematically varied. It was found that when the matching limb was differentially loaded, the error in the produced reference angle corresponded to the directional prediction of a proposed gravitational torque hypothesis. The data suggest that torque sensation is an accessory source of information in limb positioning.This research was partially supported by grants from NATO Scientific Affiars Division, RG82/0227 and US Public Health Service, NS17421 and AG05154 awarded to G. E. Stelmach     

Movement-related skin strain associated with goal-oriented lip actions

 It is generally accepted that sensory input contributes to the generation of natural movements. In most motor systems, muscle spindles, tendon organs, joint receptors, and cutaneous mechanoreceptors may provide proprioceptive information. However, the perioral area of the human face lacks muscle spindles, tendon organs, and joint receptors and is therefore a model system for the study of cutaneous afferent contributions to proprioception. This investigation examined a series of skin strains associated with lower-lip movements in human subjects to determine if such strains, which serve as stimuli for cutaneous mechanoreceptors, may underlie proprioception in the face. The results suggested that strains associated with lower-lip movements were of sufficient magnitude to elicit cutaneous mechanoreceptor discharge, as shown in recent human microneurographic studies. Further, the magnitude of multiple strains was predictive of lower-lip movement endpoints. These results highlight the potential importance of cutaneous mechanoreceptors as putative proprioceptors. Received: 16 February 1998 / Accepted: 26 May 1998