Rangos School of Health Sciences
movement system, functional performance test, electromyography, ankle sprain
Purpose: Hip muscle function has been reported to be altered in individuals with chronic ankle instability (CAI). The purpose of this study was (1) to determine whether the single leg squat test (SLST) could be used to detect differences in proximal muscle activation between individuals with and without CAI and (2) to determine if there was a difference in maximum isometric body weight normalized torque output of the hip lateral rotators, extensors, and abductors between individuals with and without CAI.
Subjects: Forty-eight subjects (14 males, 34 females; median age = 22.00 years, interquartile range (IQR) = 1.00; median height = 1.68 m, IQR = 0.15; median weight = 68.04 kg, IQR = 19.84; median body mass index = 24.41 kg/m2, IQR = 3.70) participated in this study. Subjects were separated into CAI (n = 18), coper (n = 15), and control (n = 15) groups based on published criteria.
Main outcome measures: Gluteus maximus and gluteus medius muscle activation during the SLST was measured using percent maximum voluntary isometric contraction (% MVIC) activation. Strength of the hip lateral rotators, extensors, and abductors was quantified using maximum isometric body weight normalized torque.
Results: Separate one-way analyses of variance and a Kruskal-Wallis one-way analysis of variance by ranks were used to determine group differences on these measures. The CAI group demonstrated significantly more gluteus maximus muscle activation (mean activation = 36.03% MVIC, standard deviation (SD) = 10.85% MVIC) during the SLST than both the coper (mean activation = 18.30% MVIC, SD = 10.39; p < .001) and control (mean activation = 21.04% MVIC, SD = 8.14; p < .001) groups. The CAI group also demonstrated decreased strength of the hip lateral rotators (mean maximum isometric body weight normalized torque = 0.560 Nm/kg, SD = 0.13) when compared with the coper (mean maximum isometric body weight normalized torque = 0.667 Nm/kg, SD = .009, p = .001) and control (mean maximum isometric body weight normalized torque = 0.757 Nm/kg, SD = .009, p < .001) groups. The CAI group was also significantly weaker than the control group when maximum isometric body weight normalized torque of the hip extensors was compared (median maximum isometric body weight normalized torque CAI group = 1.10 Nm/Kg, IQR = 0.15, median maximum isometric body weight normalized torque control group = 1.65 Nm/Kg, IQR = 0.37; p < .001). There were not significant differences between the groups on gluteus medius muscle activation during the SLST (p = .155) or hip abduction strength (p = .02). There were no significant differences between the coper and control groups for any of the main outcome measures.
Conclusions: Subjects with CAI performed the SLST with significantly more gluteus maximus activation than subjects without CAI. Subjects with CAI demonstrated significantly decreased strength of the hip lateral rotators and extensors than subjects without CAI.
Clinical Relevance: The results of the study suggest that the SLST has potential for use as a clinical measure of gluteus maximus muscle function in individuals with CAI. Further study is needed to determine whether the differences in activation that occurred are clinically detectable. This study’s findings also support previous work showing that individuals with CAI have weakness of the hip lateral rotators and extensors when compared to individuals without CAI.
Carroll, L. (2021). Hip Muscle Function in Individuals with Chronic Ankle Instability (Doctoral dissertation, Duquesne University). Retrieved from https://dsc.duq.edu/etd/2037