Talk: Influence of ageing and chronic stroke on postural control, muscle-tendon mechanics, and sole…
Speaker: Robyn Mildren, Johns Hopkins University (grid.21107.35)
Title: Influence of ageing and chronic stroke on postural control, muscle-tendon mechanics, and soleus muscle responses to proprioceptive stimuli during standing
Emcee: Valentina Borghesani
Backend host: Siddharth Suresh
Details: https://neuromatch.io/abstract?submis...
Paper link: https://pubmed.ncbi.nlm.nih.gov/32822...
Presented during Neuromatch Conference 3.0, Oct 26-30, 2020.
Summary: Proprioceptive sensory information from the lower limbs plays a critical role in the control of posture and balance, and changes in proprioceptive pathways with healthy ageing and following a stroke may contribute to impaired balance and falls. Here, we aimed to examine how healthy ageing and chronic stroke influence the frequency characteristics of the soleus muscle response to proprioceptive stimuli during standing. We also aimed to examine whether there are relationships between soleus responses, postural control, and muscle-tendon mechanics. We applied a continuous noisy vibration to the right or left Achilles tendon and examined responses in soleus surface EMG in a sample of 54 healthy adults across a broad age range (20–54 years) and 8 adults with chronic hemiparetic stroke. Our results showed the soleus response frequency bandwidth became progressively narrower with age, and soleus response gain was lower in older relative to young adults across a bandwidth of ~28–54 Hz. Across the age range, the amplitude of the soleus response was negatively correlated with age. We found minimal age-related differences in mechanical admittance of the muscle-tendon unit, suggesting this did not mediate the changes in soleus responses. Participants with chronic stroke had lower anteroposterior centre of pressure amplitude and frequency on the affected side, which suggests they relied more upon the less-affected limb for balance control. In addition, participants who showed an asymmetry in soleus responses characterized by larger responses on the affected side tended to have lower mechanical admittance at frequencies beyond ~20 Hz, as well as poorer motor recovery assessed with the Fugle-Meyer scale. The age-related changes in soleus responses to proprioceptive stimuli reflect progressive changes in muscle spindle morphology and stretch sensitivity, meanwhile, changes post-stroke may be related to altered muscle-tendon mechanics and postural control strategies.