Effects of sudden unexpected mechanical perturbation training aimed at the primary prevention of inversion ankle sprain on reactiveness of ankle movement and cortical activity in normal young adults

Lateral wedge insoles and their use in ankle instability

The aim of the present study is to assess the immediate effects of applying lateral wedge insoles of different heights (0.00, 0.3, 0.4, and 0.6 cm) in patients with chronic ankle instability (CAI) in normal and supinated feet during a Star Excursion Balance Test (SEBT) and in the reflex response of Peroneus Longus (PL), Peroneus Brevis (PB), and Tibialis Anterior (TA) over a 30° inversion of the feet. The effects of the height of the wedges were assessed using a double-blind, crossover design. In total, 25 participants were allocated into two groups, depending on the foot posture (Normal = 12, Supinated = 13) and performed the tests in a random fashion. Reaction time (RT) of stabilizing muscles of the ankle was measured using superficial electromyography (EMG) and postural balance with the SEBT. Foot posture did not show any significant effects on the analyzed variables. Nonetheless, the use of a 0.3 cm external rearfoot wedge (PB p = 0.002; PL p = 0.066 and TA p = 0.006) and 0.6 cm (PB p = 0.043; PL p = 0.058 and TA p = 0.071) reduces RT in stabilizing muscles of the ankle and improves results in SEBT, except for the anterolateral direction, in subjects with CAI. Therefore, our results suggest that the use of lateral wedge insoles could reduce RT and improve dynamic balance in chronic ankle instability.

The impact of unexpected platform perturbation on ankle proprioception ability in static and dynamic starting positions

AIMS

To examine the relationship between ankle proprioception and the ability to maintain balance with increased magnitudes of unexpected perturbations; and to compare the participants' ability to maintain balance following perturbations when starting from static and dynamic positions.

METHODS

Sixty physical education students (average 24.6 years) were tested for proprioception ability (AUC scores) and balance challenges presented on a perturbation treadmill. The degree at which participants lost postural balance was recorded in seven starting positions: standing-eyes-open (SO), standing-eyes-closed (SC), tandem-dominant (TD), tandem non-dominant, (TND) single-leg lateral side perturbation (SLP), single-leg medial side perturbation (SMP), and walking. Perturbation scores were analysed divided by tertiles. Multidimensional Unfolding SPSS Statistics 25 (PREFSCAL) was used to examine the relationships between data sets.

RESULTS

AUC scores of both dominant and non-dominant legs were significantly correlated with SO (r = 0.316; r = 0.445), SC (r = 0.364; r = 0.413), TD (r = 0.346; r = 0.308), and walking (r = 0.265; r = 0.439), respectively. In the dominant-leg, AUC scores of individuals with below-median SO scores were significantly worse compared to those with median SO scores (p = .046). In the non-dominant leg, individuals with above-median SC had significantly better AUC scores compared to those with lower-than-median SC (p = .008). Those with median and above-median SO and walking achieved better AUC scores than those with below-median (SO: p = .049, p = .004; walking: p = .016, p < .001, respectively). In dimension I, the SLP and SMP were located opposite one another; in dimension II, the TD and TND were located at the upper side, whereas SC, SO and walking were at the lowest side.

CONCLUSIONS

AUC scores were significantly correlated with the level at which postural balance was lost, whereby the better the proprioception ability, the better the ability to maintain balance. As such, the ability to maintain balance is harder in tandem positions than in standing and walking positions. This ability differed when perturbations were to the lateral or medial sides.

Screening for laterally deviated plantar pressure during stance using the Cumberland ankle instability tool and anthropometric measures

This study developed a method that predicts laterally deviated plantar pressure during stance by lower limb anthropometrics and self-reported ability to stop an ankle which has started to roll over. Thirty-two males ran on a treadmill for 2 minutes at 11 km/h. Foot pressure data were collected by a pressure insole system for classifying the participants as medial or lateral strikers. Cumberland Ankle Instability Tool score, Tegner Activity Scale score, foot arch height, active and passive ankle and knee range of motion, bi-malleolar width, foot length, foot width and calf circumference were measured. Binary logistic regressions were performed to produce a model which estimated if an individual showed laterally deviated foot pressure during stance. The model utilized the score of Cumberland Ankle Instability Tool Question 8, active and passive knee joint external rotation, height, body mass and bimalleolar width (explained variance of 47.3%, p = 0.037), producing a sensitivity of 71.4% and a specificity of 54.5%. A validation trial on another 15 runners reported a 73.3% accuracy in prediction if they are medial or lateral strikes.