Sensorimotor deficits after stroke contribute to increased risk of falls. Sensory input related to the derivative of ankle sways shows a strong relationship with plantarflexor electromyography (EMG) modulation in healthy controls, suggesting that information regarding speed of movement facilitates the prediction of movement outcome (Masani et al. 2003). The purpose of this study was to examine the relationship of ankle plantarflexor EMG with the anterior-posterior centre of pressure (APCOP) velocity and displacement of people with stroke compared to controls using high density surface EMG (HDsEMG). Methods: Ten people with chronic stroke (mean ± sd 66.2 ± 9 yrs, 8 males) and ten age-matched controls (7 males) participated. Participants stood with each foot on a separate force platform. Anteriorly-directed loads were dropped by a pulley system and cable attached to a belt around the participants’ pelvis. Loads of 1% body mass were added every 25-30s until a total of 5% body mass was reached. The static maintenance of standing balance was determined for 15s between loads. The APCOP displacement was measured simultaneously with HDsEMG from the soleus (SOL) (24 electrode grid, 2 cm interelectrode distance), medial (MG) and lateral gastrocnemius (LG) (20 electrode grids each, 1.5 cm interelectrode distance) of both legs. APCOP velocity was derived from APCOP displacement. For each channel, cross-correlation values between rectified, 4 Hz low-pass filtered EMGs (EMG envelopes; 18 bipolar for SOL, 16 for MG and LG) and APCOP displacement and velocity during the static maintenance of standing balance were computed; for each muscle, the median correlation value was considered as representative. Results: The median correlation of each plantarflexor EMG envelope with the APCOP velocity was stronger than with the APCOP displacement in all groups (paretic, non-paretic and control; p<0.01). Furthermore, correlations were significantly higher in MG than LG and SOL muscles in controls (p<0.01), and both MG and LG were significantly higher than SOL in the non-paretic leg (p<0.01), but the correlations were not significantly different amongst the paretic plantarflexors. Conclusions: These data suggest that sensory information reflected in APCOP velocity interacts more strongly than APCOP displacement with plantarflexor EMG activity in plantarflexor muscles in people with stroke and controls. However, the gastrocnemii EMG activity demonstrates a greater relationship with APCOP velocity than the SOL muscle in non-paretic and control groups but not in paretic muscles. This may be related to remodeling of the plantarflexors following stroke, moreso in the gastrocnemii.

Ankle plantarflexor activity is more strongly related to centre of pressure velocity than displacement with external perturbation in people with stroke and healthy controls / C. L., Pollock; T. D., Ivanova; A., Gallina; Martins, Taian; S. J., Garland. - ELETTRONICO. - (2014), pp. 1129-1130. (Intervento presentato al convegno Neuroscience 2014 tenutosi a Washington nel November 15-19).

Ankle plantarflexor activity is more strongly related to centre of pressure velocity than displacement with external perturbation in people with stroke and healthy controls

MARTINS, TAIAN;
2014

Abstract

Sensorimotor deficits after stroke contribute to increased risk of falls. Sensory input related to the derivative of ankle sways shows a strong relationship with plantarflexor electromyography (EMG) modulation in healthy controls, suggesting that information regarding speed of movement facilitates the prediction of movement outcome (Masani et al. 2003). The purpose of this study was to examine the relationship of ankle plantarflexor EMG with the anterior-posterior centre of pressure (APCOP) velocity and displacement of people with stroke compared to controls using high density surface EMG (HDsEMG). Methods: Ten people with chronic stroke (mean ± sd 66.2 ± 9 yrs, 8 males) and ten age-matched controls (7 males) participated. Participants stood with each foot on a separate force platform. Anteriorly-directed loads were dropped by a pulley system and cable attached to a belt around the participants’ pelvis. Loads of 1% body mass were added every 25-30s until a total of 5% body mass was reached. The static maintenance of standing balance was determined for 15s between loads. The APCOP displacement was measured simultaneously with HDsEMG from the soleus (SOL) (24 electrode grid, 2 cm interelectrode distance), medial (MG) and lateral gastrocnemius (LG) (20 electrode grids each, 1.5 cm interelectrode distance) of both legs. APCOP velocity was derived from APCOP displacement. For each channel, cross-correlation values between rectified, 4 Hz low-pass filtered EMGs (EMG envelopes; 18 bipolar for SOL, 16 for MG and LG) and APCOP displacement and velocity during the static maintenance of standing balance were computed; for each muscle, the median correlation value was considered as representative. Results: The median correlation of each plantarflexor EMG envelope with the APCOP velocity was stronger than with the APCOP displacement in all groups (paretic, non-paretic and control; p<0.01). Furthermore, correlations were significantly higher in MG than LG and SOL muscles in controls (p<0.01), and both MG and LG were significantly higher than SOL in the non-paretic leg (p<0.01), but the correlations were not significantly different amongst the paretic plantarflexors. Conclusions: These data suggest that sensory information reflected in APCOP velocity interacts more strongly than APCOP displacement with plantarflexor EMG activity in plantarflexor muscles in people with stroke and controls. However, the gastrocnemii EMG activity demonstrates a greater relationship with APCOP velocity than the SOL muscle in non-paretic and control groups but not in paretic muscles. This may be related to remodeling of the plantarflexors following stroke, moreso in the gastrocnemii.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2579146
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