Abstract
Training improves balance control in older adults, but the time course and neural mechanisms underlying these improvements are unclear. We studied balance robustness and performance, H-reflex gains, paired reflex depression (PRD), and co-contraction duration (CCD) in ankle muscles after one and ten training sessions in 22 older adults (+65yrs). Mediolateral balance robustness, time to balance loss in unipedal standing on a platform with decreasing rotational stiffness, improved (33%) after one session, with no further improvement after ten sessions. Balance performance, absolute mediolateral center of mass velocity, improved (18.75%) after one session in perturbed unipedal standing and after ten sessions (18.18%) in unperturbed unipedal standing. CCD of soleus/tibialis anterior increased (16%) after ten sessions. H-reflex gain and PRD excitability did not change. H-reflex gains were lower and CCD was higher in participants with more robust balance at the last time-point and CCD was higher in participants with better balance performance at several time-points. Changes in robustness and performance were uncorrelated with changes in CCD, H-reflex gain, or PRD. In older adults, balance robustness improved over a single session, while performance improved gradually over multiple sessions. Changes in co-contraction and excitability of ankle muscles were not exclusive causes of improved balance.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
This version of the manuscript has been revised to update the title of the article and the introduction. The title has been updated, to one-session and ten-session, instead of short-term and long-term training. The introduction has been updated to clarify the novelty of the research.