Balance mechanisms during standing and walking in young and older adults

Abstract

Maintaining balance is controlled by two different processes: feedforward and feedback control. Feed-forward control is used prior to performing voluntary movements whereas feedback control is used to correct for unexpected perturbations. Studies suggested that age-related changes in postural responses may contribute to increased risk of falls in older adults. To address whether Tai Chi training can induce improved patterns of feed-forward control, voluntary arm elevations during standing were performed. Compared to age-matched controls, smaller displacements of the center of pressure were found among older adults who practice Tai Chi. This may suggest adapted feed-forward control induced by training. To investigate feedback control, perturbations were applied while walking with various arm constraints. Context-dependent modulation in response amplitude was found with changing levels of postural threat in older adults, comparable to young adults. Delayed onset latencies and frequent inhibition of Soleus may suggest less effective balance strategies employed in older adults, and an increased risk of falling.