Muscle-Activation Onset Times With Shoes and Foot Orthoses in Participants With Chronic Ankle Instability

Abstract

Earlier onset of muscle activity was most apparent in the SCFO condition for ankle and knee muscles but not for hip muscles during the transition from double-legged to single-legged stance. These findings might help clinicians understand how shoes and foot orthoses can influence neuromuscular control in participants with CAI.

Lower extremity muscle activation onset times during the transition from double-leg stance to single-leg stance in anterior cruciate ligament injured subjects

“…The results of our study show that control subjects initiated muscle activity before the time point where the upcoming supporting leg is suggested to be loaded (Mx onset) (Dingenen et al, 2015b(Dingenen et al, , 2015c for all muscles except gluteus maximus in the eyes closed condition. This anticipatory muscle activity prepares the lower extremity for the upcoming postural perturbation created by the voluntary movement (shifting the weight from DLS to SLS) and is believed to be beneficial to develop efficient joint stabilization strategies (Aruin & Latash, 1995;Bouisset & Do, 2008;Hodges & Richardson, 1997;Wikstrom et al, 2006;Williams et al, 2001).…”

“…An increase of muscle activity before Mx onset is reflected by a negative value for the onset of muscle activity. A positive value indicates an increase of muscle activity after Mx onset (Dingenen et al, 2015b(Dingenen et al, , 2015c.…”

“…This is followed by a movement towards the single standing leg to finally finish on one leg (SLS phase) (Dingenen et al, 2013). Onset of muscle activity was calculated with respect to the mediolateral moment of force (Mx) (Dingenen et al, 2015b(Dingenen et al, , 2015c. First, the average Mx was calculated for the DLS phase.…”

“…The raw EMG data were first rectified and then filtered by 6th order Butterworth low-pass filter with a cut-off frequency of 45 Hz to generate the envelope of the EMG. A fixed window of 100 ms before the stance transition (during the DLS phase) was compared with a moving window of the same length along the measurement (Dingenen et al, 2015b(Dingenen et al, , 2015c). An increase of more than 2 standard deviations on top of the average baseline activity was identified as the onset of muscle activity in reaction to the transition (Hodges & Bui, 1996).…”

“…The procedure used in this study is based on previous studies (Dingenen et al, 2013(Dingenen et al, , 2015(Dingenen et al, , 2015a(Dingenen et al, , 2015b(Dingenen et al, , 2015c. Subjects were asked to stand barefoot on a force plate with the feet separated by the width of the hips and the arms hanging loosely at the side.…”