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Thur, Dec 8

Speaker: Matt Holmes, M.Sc.

Title: Increased coactivation is accompanied by a reduced capacity to modulate afferent input in the elderly

Abstract:  Older adults tend to use greater amounts of antagonist and accessory muscle activity than young adults when performing the same movements.  As antagonist muscles oppose the actions of agonist muscles, heightened levels of antagonist coactivation are typically considered undesirable.  However, the mechanisms that underlie greater amounts of coactivation in the elderly remain unclear.  Recent evidence suggests that young adults tend to rely on afferent feedback to produce corrective actions when performing steady contractions, whereas this capacity declines with age and is replaced by a feedforward strategy of increased antagonist coactivation to stiffen the joint.  This observation suggests that older adults become less reliant on feedback mechanisms during voluntary movement and become increasingly reliant on feedforward mechanisms.  During this talk I will share recent data from Roger Enoka’s lab that support these ideas.  Furthermore I will present data that suggest these declines in neuromuscular function precede the reduction in muscle strength and mass associated with sarcopenia.

Host: Drs. Heckmann & Rymer