Agonist and antagonist activation at the ankle monitored along the swing phase in hemiparetic gait

Antagonist Activation Measurement in Triceps Surae Using High-Density and Bipolar Surface EMG in Chronic Hemiparesis

After a stroke, antagonist muscle activation during agonist command impedes movement. This study compared measurements of antagonist muscle activation using surface bipolar EMG in the gastrocnemius medialis (GM) and high-density (HD) EMG in the GM and soleus (SO) during isometric submaximal and maximal dorsiflexion efforts, with knee flexed and extended, in 12 subjects with chronic hemiparesis. The coefficients of antagonist activation (CAN) of GM and SO were calculated according to the ratio of the RMS amplitude during dorsiflexion effort to the maximal agonist effort for the same muscle. Bipolar CAN (BipCAN) was compared to CAN from channel-specific (CsCAN) and overall (OvCAN) normalizations of HD-EMG. The location of the CAN centroid was explored in GM, and CAN was compared between the medial and lateral portions of SO. Between-EMG system differences in GM were observed in maximal efforts only, between BipCAN and CsCAN with lower values in BipCAN (p < 0.001), and between BipCAN and OvCAN with lower values in OvCAN (p < 0.05). The CAN centroid is located mid-height and medially in GM, while the CAN was similar in medial and lateral SO. In chronic hemiparesis, the estimates of GM hyperactivity differ between bipolar and HD-EMGs, with channel-specific and overall normalizations yielding, respectively, higher and lower CAN values than bipolar EMG. HD-EMG would be the way to develop personalized rehabilitation programs based on individual antagonist activations.

Characteristics of muscle synergy extracted using an autoencoder in patients with stroke during the curved walking in comparison with healthy controls

BACKGROUND AND OBJECTIVE

This study investigated the spatial and temporal features of muscle synergy during two types of curved walking (CW), according to whether the analyzed legs were located on the outside (OCW) or inside (ICW) on the basis of the curve direction during CW, in patients with stroke.

METHODS

Thirteen patients with stroke and seven age-matched healthy controls participated in this study. Using the autoencoder technique, four muscle synergies were extracted from eight muscles of the paretic legs in patients with stroke and the dominant legs in healthy controls. Walking speed, variance accounted for (VAF) of the four synergies, and each synergy with the same number were compared. Pearson's correlation and activation peak timing calculation were used to identify spatial and temporal features, respectively.

RESULTS

Regarding walking speed in patients with stroke, ICW was significantly faster than OCW (P = 0.027). Regarding spatial features, muscle weighting values of patients with stroke in synergy 3 that were mainly involved in the early swing phase had the lowest similarity [r = 0.30] during OCW, and synergy 4 that was mainly involved in the late swing phase had the lowest similarity [r = 0.39] during ICW compared to the healthy group. Meanwhile, in terms of temporal features, activation peak timings of patients with stroke in synergy 1, which was mainly involved in the early stance phase, and synergy 2, which was mainly involved in the mid-late stance phase, were significantly delayed during OCW (P < .001, P = 0.003), while peak timings of synergy 1 and synergy 3 were delayed during ICW (P = .004, P = .002).

SIGNIFICANCE

Based on distinctive features of spatial synergy during the swing phase of CW and temporal synergy during the swing-stance transition phase of CW in patients with stroke in gait rehabilitation, specific approaches need to be considered depending on the curve direction and each gait phase.

Effectiveness of a wearable ankle-tubing gait training on ankle kinematics and motor control in hemiparetic stroke

BACKGROUND: While excessive ankle plantarflexion is a common neuromuscular impairment resulting from insufficient coordination of selective ankle neuromotor control and kinematics during gait. We recently developed a wearable, inexpensive and sustainable wearable ankle-tubing gait training (WAGT) aimed at improving selective ankle motor control and kinematic coordination. OBJECTIVE: We investigated the effects of WAGT on tibialis anterior (TA) and gastrocnemius (GCM) muscle electromyography (EMG) activity, TA: GCM muscle imbalance ratio, and ankle joint kinematics during gait in hemiparetic stroke patients. METHODS: A convenience sample of 33 participants (15 non-stroke healthy adults and 18 hemiparetic stroke patients) underwent standardized electromyography and kinematic biomechanical tests under conventional gait training (CGT) and WAGT conditions. Analysis of variance (ANOVA) was used to determine the significance of differences in the TA: GCM muscle activation, muscle imbalance ratio, and ankle joint kinematics before and after the intervention and between the two groups at P < 0.05. RESULTS: WAGT was more effective than CGT in improving TA muscle activation (P < 0.01), TA: GCM muscle imbalance ratio (P < 0.01), and kinematic movement (P < 0.01) in adults with or without hemiparetic stroke. CONCLUSIONS: This study demonstrated that WAGT is relatively ease to design, wear and affordable to most clinicians and patients, hence it is suitable for many health care applications to correct gait-related movement abnormalities presented in the hemiparetic stroke patients.