Fatigue of Sustained Tetanic Contribctions

Summary. The purpose of this investigation has been to examine the mechanism behind the process of fatigue during sustained titanic contractions. Mechanical responses and action potentials have been recorded from the adductor policies muscle in man and from the flexor digit rum long us, gastronomies and sole us muscles in rabbit. The following results were obtained: 1. Our results from man support the view of Merton (1954) that the process of fatigue developing during a sustained titanic contraction is a purely peripheral phenomenon. 2. It is impossible to produce a stronger or more prolonged tetanic contraction by indirect supramaximal stimulation than by maximal voluntary effort. 3. Superposition of indirect stimulation during maximal voluntary effort shortens the duration of the contraction. 4. We found in contrast to Merton that the action potentiais always decrease during the reduction of the mechanical response. The results are discussed in Ielation to previous investigations in this field, especially to those of Brown and Burns (1949) and Merton (1954).