Original research
Effect of lace-up ankle braces on electromyography measures during walking in adults with chronic ankle instability

https://doi.org/10.1016/j.ptsp.2014.02.002Get rights and content

Abstract

Background

Lace-up ankle braces reduce the incidence of ankle sprains and have been hypothesized to do so through both mechanical and neuromuscular mechanisms.

Objective

To determine the effect of lace-up ankle braces on surface electromyography (sEMG) measures during walking in adults with chronic ankle instability (CAI).

Design

Randomized crossover.

Setting

Laboratory.

Participants

Fifteen adults with CAI.

Main outcome measures

Surface EMG activity was recorded from the anterior tibialis, peroneus longus, lateral gastrocnemius, rectus femoris, biceps femoris and gluteus medius during treadmill walking with and without lace-up ankle braces. The dependent variables were sEMG amplitude 100 ms pre- and 200 ms post-initial contact, time of activation relative to initial contact, and percent of activation across the stride cycle.

Results

When compared to no brace, ankle bracing resulted in lower pre-contact amplitude of the peroneus longus (p = 0.02). The anterior tibialis, peroneus longus, rectus femoris, and gluteus medius were activated later relative to initial contact (p < 0.03). The peroneus longus and rectus femoris were activated for a shorter percentage of the stride cycle (p < 0.05).

Conclusion

Braces cause a change in neuromuscular activity during walking. Clinicians should be aware of these changes when prescribing braces, as it may relate to the mechanism in which braces decrease sprains.

Introduction

Injuries to the ankle are one of the most common musculoskeletal injuries in athletics (Hootman et al., 2007, Waterman et al., 2010). People who sprain their ankle will remain about 5 times more likely to re-injure their ankle (McKay, Goldie, Payne, & Oakes, 2001). It is common for individuals who sprain their ankle to have prolonged symptoms and perceived instability that lasts greater than a year (van Rijn, van Os, Bernsen, Luijsterburg, Koes, & Bierma-Zeinstra, 2008). This condition is commonly known as chronic ankle instability (CAI) (Delahunt et al., 2010, Hertel, 2002). These symptoms can lead to decreased athletic performance, prolonged removal from participation and a lowered quality of life (van Rijn et al., 2008).

It can be a challenge for clinicians to improve function in people with CAI because of the complexity of the characteristics. Past studies have shown individuals with CAI to have deficits in proprioception (Munn, Sullivan, & Schneiders, 2010), postural control (Docherty et al., 2006, Evans et al., 2004), lower extremity muscle activity (Delahunt et al., 2006a, Feger et al., 2014) and have been found to have alterations in gait (Chinn et al., 2013, Delahunt et al., 2006a) and landing activities (Delahunt, Monaghan, & Caulfield, 2006b). The etiology of CAI is clearly a multifactorial issue (Freeman et al., 1965, Hertel, 2008, Hiller et al., 2011).

Prophylactic ankle bracing has been used to prevent initial and recurrent injuries to the lateral ankle ligaments and is often used by individuals with CAI to enhance ankle stability. Recent studies have shown the use ankle braces caused a 70% reduction in acute ankle injuries among those with previous ankle injury and a 57% reduction among those with no history of ankle injury in high school athletes (McGuine et al., 2011, McGuine et al., 2012). An interesting finding from these studies (McGuine et al., 2011, McGuine et al., 2012) is that the severity of the ankle sprains that occurred did not change with the application of a brace.

Previous literature demonstrating that ankle bracing restricts range of motion measurements (DiStefano et al., 2008, Sefton et al., 2007) have been performed in a laboratory and may not directly relate to the ability for an ankle brace to decrease range of motion when a lateral ankle injury mechanism occurs during high velocity functional activities. Neuromuscular adaptations also may have a contributing role in the ability to prevent ankle sprains. Studies utilizing trap door mechanisms (Cordova and Ingersoll, 2003, M. L. Cordova et al., 2000, Shima et al., 2005) or those measuring H-reflexes (Nishikawa and Grabiner, 1999, Sefton et al., 2007) have found increased peroneal reflex activity and motonueron pool excitability with ankle brace application. Increased cutaneous and joint mechanoreceptor stimulation from braces is thought to improve proprioception (Feuerbach, Grabiner, Koh, & Weiker, 1994). Gait alterations such as increased maximum pronation and pronation velocity (Nishikawa, Kurosaka, Yoshiya, Lundin, & Grabiner, 2002) and decreased plantarflexion at initial contact following a jump task (DiStefano et al., 2008) have also been associated with the use of ankle braces. These loading and biomechanical changes may result in a decreased chance of the foot being in a position more prone to ankle sprain.

The use of surface electromyography (sEMG) allows for non-invasive approximation of muscle activity. Previous literature utilizing sEMG related to ankle dynamics has primarily been focused on peroneus longus activation during an unanticipated perturbation (Cordova, Armstrong, Rankin, & Yeasting, 1998). While this data adds important baseline information, the translation of these results to more dynamic tasks is uncertain. A recent study on individuals with and without CAI found altered lower extremity muscle activation during walking (Feger et al., 2014). Specifically, CAI participants were found to activate lower extremity muscles earlier in the stride cycle and, in regards to the peroneus longus, for a longer percentage of the stride cycle compared to healthy controls (Feger et al., 2014). The ability for ankle braces to affect these alterations, however, is unknown. Therefore, the purpose of this study was to determine what effect lace-up ankle braces had on lower extremity sEMG amplitude and timing during treadmill walking in patients with CAI.

Section snippets

Design

A controlled laboratory study using a randomized crossover design was performed. The independent variable was condition, brace vs. no brace. Dependent variables were sEMG amplitude before and after initial contact, onset timing relative to initial contact, and percent activation time across the entire stride cycle of the (anterior tibialis (AT), peroneus longus (PL), lateral head of the gastrocnemius (LG), rectus femoris (RF), biceps femoris (BF), and gluteus medius (GM)). The randomization of

Amplitude measures

The descriptive measures for the sEMG amplitude results are shown in Tables 2 and 3. The pre-contact amplitude of the PL was significantly lower in the brace condition when compared to the no brace condition (0.36 ± 0.18 vs. 0.46 ± 0.23, p = 0.02) Table 2. There were no significant differences for any of the muscles between conditions in the post-contact amplitude measures Table 3.

Onset timing

The descriptive measures for the sEMG onset timing are shown in Table 4. The AT, PL, RF and GM were activated

Discussion

Our results demonstrate that lace-up ankle braces cause alterations in lower extremity muscle activation during walking in physically active young adults with CAI. Specifically, bracing caused a decrease in the PL pre-contact amplitude, delayed activation in the AT, PL, RF and GM, and overall decreased activation of the PL and RF throughout the stride cycle. Our results provide insight into the potential physiologic mechanisms by which lace-up ankle braces may reduce the risk of ankle sprains.

Conclusions

We found that in active individuals with CAI, a lace-up ankle brace reduced PL pre-contact amplitude, delayed activation of the AT, PL, RF and GM and decreased total on-time of the PL and RF throughout the stride cycle during treadmill walking. These differences between conditions may suggest that the alteration in muscle function may contribute to the mechanism in which lace-up braces decrease the recurrence of ankle sprains in people with CAI. Clinicians should be aware of these changes when

Conflict of interest

None declared.

Ethical approval

The University's Institution Review Board for Health Sciences (IRB-HSR-15877) has approved this project.

Funding

None declared.

Acknowledgment

We would like to acknowledge Mark Feger for his contributions to data collection and analysis.

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