Control of Acceleration During Sudden Ankle Supination in People With Unstable Ankles

Abstract

Study Design:Comparative study of differences in functional control during ankle supination in the standing position in matched stable and unstable ankles (ex post facto design). Objectives: To document acceleration and deceleration during ankle supination in the standing position and to determine differences in control of supination perturbation between stable and unstable ankles. Background: Repetitive ankle sprain can be explained by mechanical instability only in a minority of cases. Exercise therapy for ankle instability is based on clinical experience. Joint stability has not yet been measured in dynamic situations that are similar to the situations leading to a traumatic sprain. The process of motor control during accelerating ankle supination has not been adequately addressed in the literature. Methods and Measures: Pdtients with complaints of ankle instability (16 unstable ankles) and nonimpaired controls (18 stable ankles) were examined (N = 17 subjects, 10 women and 7 men). The average age was 23.7 2 5.0 years (range, 20-41 y). Control of supination speed was studied during 50" of ankle supination in the standing position using accelerometry (total supination time and deceleration times) and electromyography (latency time). Timing of motor response was estimated by measuring electromechanical delay. Results: The presence of an early, sudden, and presumably passive slowdown of ankle supination in the standing position was observed. Peroneal muscle motor response was detected before the end of the supination. Unstable ankles showed significantly shorter total supination time (109.3 ms versus 124.1 ms) and significantly longer latency time (58.9 ms versus 47.7 ms). Conclusions: Functional control in unstable ankles is less efficient in decelerating the ankle during the supination test procedures used in our study. Our conclusions are based on significantly faster total supination and significantly slower electromyogram response in unstable ankles. The results support the hypothesis that both decelerating the total supination movement during balance disturbance and enhancing the speed of evertor activation through exercise can be specific therapy goals. I Orthop Sports Phys J%er ,?OOl;3l:74l-752.

The Alteration of Neuromuscular Control Strategies During Gait Initiation in Individuals with Chronic Ankle Instability

“…Former conducted studies showed that alteration during gait initiation (GI) and landing followed ankle instability, which further supported central alteration or open-loop neuromuscular control alteration in patients with CAI (10,11). On the other hand, previous studies suggested proprioceptive deficits (12) and peroneal muscles reaction time delay in response to unexpected perturbation, which showed deficit in closed-loop neuromuscular control, in patients with CAI (13); however, some contradictory studies showed no difference in peroneal muscles reaction time between patients with ankle instability and healthy individuals (14,15). Gutierrez et al, (9) suggested that closed-loop control may have no important role in maintaining the stability of ankle during perturbation (9).…”

Analysis of acceleration time of ankle in long-distance runners and triathletes

“…7 The phenomenon of acceleration has been investigated through methodologies such as trapdoor experiments and electromyography. [8][9][10] However, isokinetic analysis is an assessment method that is more dynamic 11 and shows a behavior that is closer to the functionality of the sport.…”

Repeated Ankle Sprains and Delayed Neuromuscular Response: Acceleration Time Parameters

“…Other studies, however, showed a significant difference in evertor muscles latency time when comparing stable and unstable ankles during inversion movement of 30°. 22,24,26,30,37,45 Evertor muscles of unstable ankles were shown to have a longer latency time and the latency time of the fibularis longus and brevis muscles increased with plantar flexion. 32,37 Obviously, these conflicting results require further research with different methods.…”

“…Consequently, neuromuscular dysfunction is seen as an important factor in the etiology of CAI. 14,[22][23][24][25][26]30,37,45 Most published studies on reaction time 9,11,18,19,24,26,30,36,45 are based on trapdoor experiments, measuring surface electromyography (EMG) response of lower leg muscles. To assess muscle recruitment, latency time (defined as the time between disturbance of the equilibrium and the first EMG signal) is often used as the outcome measure.…”

“…Furthermore, EMG studies have used relatively small inversion movements on trapdoor mechanisms not exceeding 35°of inversion. 45 However, an inversion trauma mostly occurs in dynamic situations like walking or running. Therefore we looked for a dynamic test that would allow an inversion/eversion (INV/EVER) movement over a large range of motion.…”