Participants with chronic ankle instability experienced significantly earlier muscle activation times in the ankle and knee muscles, but not the hip muscles, when wearing shoes and foot orthoses, indicating that shoes and foot orthoses have significant neuromuscular effects, according to study results published in the Journal of Athletic Training.
“Next to the high numbers of ankle sprains both in the athletic and general population, the high recurrence rates and risk for developing chronic ankle instability are even more concerning,” Bart Dingenen, MSc, PT, of the Department of Rehabilitation Sciences at KU Leuven Musculoskeletal Rehabilitation Group in Belgium and author of the study, told O&P News. “Although the pathomechanisms of chronic ankle instability are multifactorial in nature, alterations in neuromuscular control have been shown in patients with chronic ankle instability not only around the injured ankle joint, but also in the muscle surrounding more proximal joints (knee and hip).”
Mixed findings on orthoses in past studies
Foot orthoses have often been used as an intervention strategy in patients with chronic ankle instability to improve clinical outcomes, but the mechanisms behind their clinical effectiveness have not been clear. “Traditionally, the clinical effect of shoes and foot orthoses has been attributed to alterations in kinematics, but mixed and inconsistent findings have been reported in literature,” Dingenen said.
He and his colleagues conducted a cross-sectional study to evaluate the influence of shoes and foot orthoses on lower extremity muscle activation patterns in 15 participants with chronic ankle instability. All participants had been using foot orthoses before the study. The researchers evaluated participants’ muscle activation onset times in the ankle, knee and hip muscles during transition from a double-legged to single-legged stance.
“This task has previously been proven to discriminate between noninjured subjects and subjects with lower extremity pathologies, including chronic ankle instability, when performed barefoot,” Dingenen said.
Participants performed the transition task with their eyes open and eyes closed in four experimental conditions: barefoot, wearing shoes without foot orthoses, wearing shoes with standard foot orthoses and wearing shoes with customized foot orthoses while standing on a single force plate. Researchers recorded the activity of nine lower extremity muscles using surface electromyography and calculated the muscle activation onset time of each muscle when transitioning to single-legged stance.
Best outcomes connected to custom foot orthoses
The researchers recorded earlier muscle activation onset times during the condition in which participants wore shoes with custom foot orthoses compared with the barefoot condition for the peroneus longus and tibialis anterior in the ankle and in the vastus medialis and vastus lateralis at the knee. They also found that the peroneus longus was activated earlier in the conditions in which participants wore shoes only and in which they wore shoes with standard orthoses compared with the barefoot condition.
Dingenen and colleagues reported the effects were more prominent in the conditions in which participants wore shoes with customized foot orthoses as opposed to new standardized foot orthoses.
“This finding may indicate that a certain adaptation period is needed before altered muscle activation patterns can be fully expected,” he said. “The sensory input coming from the ankle and foot may alter and become more reliable for the central nervous system when using the foot orthoses to which the participants were adapted, which may subsequently alter the motor output, leading to a kind of neuromuscular ‘bottom-up’ effect. On the other hand, it cannot be excluded that mechanical alterations, although minimal, may play an interactive role with these sensory mechanisms to finally alter the muscle activation patterns.”
Dingenen and his colleagues suggested that others use caution when generalizing findings from studies in which only barefoot conditions are conducted because shoes and foot orthoses are often worn during daily activities.
He added that future studies in this area should focus on longitudinal follow-up to evaluate how the alterations in neuromuscular control develop over time. In addition, he suggested that researchers evaluate possible interactive effects of foot orthoses with exercise therapy in patients with chronic ankle instability. – by Tina DiMarcantonio
- Dingenen, et al. J Athl Train. 2015;50(7):688-696, doi: 10.4085/1062-6050-50.2.02
Disclosure: Dingenen reports no relevant financial disclosures.