Voluntary activation of maximal single and all finger power grip contractions.

When all four fingers are engaged together during a grip strength contraction, the force produced by an individual finger is less than the force produced when it acts in isolation. The purpose of this study was to evaluate whether the reduced force output of a digit during an all-finger grip contraction is due to a decline in voluntary activation. Fifteen young adults ( = 7 females) completed voluntary contractions of the index finger in isolation and all fingers together in a dynamometer capable of separately recording forces from each finger during voluntary and electrically evoked contractions.