Noise-Enhanced Eversion Force Sense in Ankles With or Without Functional Instability

Perceived ankle instability and cutaneous reflex modulation during gait

Cutaneous reflex modulation during rhythmic ambulation is an important motor control mechanism to help minimize stumbling following an unexpected perturbation. Previous literature found individuals with chronic ankle instability (CAI) experience altered reflex patterns compared to healthy controls. Considering CAI is characterized by intermittent feelings of ankle instability, researchers have speculated that these alterations are related to perceived instability. Our purpose was to determine whether variability and magnitude of cutaneous reflex amplitudes can predict perceived instability levels following sural nerve stimulation during gait. Forty subjects walked while receiving random stimulations and reported their perceived instability. Middle latency reflexes among lower leg muscles were calculated using data derived from surface electromyography. Hierarchical logistical regressions revealed a positive relationship between reflex variability of the peroneus longus and lateral gastrocnemius muscles and perceived instability during midstance. This suggests subjects with consistent reflexes following sural nerve stimulation develop a certain level of perceptual expectation resulting in generally lower feelings of ankle instability, while subjects with more variable motor outputs perceive greater instability at the supraspinal level. Cutaneous reflex variability during stance may be an important objective outcome measure to monitor neuromuscular recovery throughout a rehabilitation or as a potential predictor of future lateral ankle sprains.

Ultrasonography Comparison of the Plantar Fascia and Tibialis Anterior in People With and Without Lateral Ankle Sprain: A Case-Control Study

OBJECTIVE

The purpose of the present study was to evaluate the thickness of the plantar fascia (PF) at the insertion of the calcaneus and the midfoot and forefoot fascial locations, in addition to the thickness of the tibialis anterior, by ultrasound imaging in individuals with and without lateral ankle sprain (LAS).

METHODS

A sample of 44 participants was recruited and divided in 2 groups: 22 feet with a prior diagnosis of grade 1 or 2 LAS (case group) and 22 feet without this condition (healthy group). The thickness and cross-sectional area were evaluated by ultrasound imaging in both groups.

RESULTS

Ultrasound measurements of the PF at the calcaneus, midfoot, and forefoot showed statistically significant differences (P < .05), with a decrease in thickness in the LAS group relative to the healthy group. For the thickness and cross-sectional area of the tibialis anterior, no significant differences (P < .05) were observed between groups.

CONCLUSION

The thickness of the PF at the calcaneus, midfoot, and forefoot is reduced in individuals with LAS relative to the healthy group.

The use of electromyography for the assessment of sense of muscular effort: a test-retest reliability study

This study sought to examine the test-retest reliability to measure sense of muscular effort with electromyography (EMG). The EMG activity of the tibialis anterior muscle from 23 participants was recorded. Targets of EMG amplitudes produced at 10 and 20% of the maximum voluntary contraction (MVC) were calculated. Participants matched the target EMG level with and without visual feedback (FB). With NFB, the reliability was good to excellent when errors were represented as the average standard deviation (SD) of the error from the target (ICC_1,2 = 0.75 and 0.69 for 10 and 20% targets, respectively). Also, reliability was good when errors were presented as the average SD as a percentage of the MVC EMG (intraclass correlation coefficient (ICC_1,2) = 0.67 and 0.66, respectively, for 10 and 20% targets). Standard deviation around the target was the most reliable method to represent the error. This approach could be used as a simple cost-effective method to assess the sense of muscular effort.