Muscle inactivation: an assessment of the interpolated twitch
technique.
Behm, D. G., D. M. M. St-Pierre, D. Perez.
School of Physical and Occupational Therapy, McGill University,
3654 Drummond St., Montreal Quebec, H3G 1Y5
APStracts 3:0272A, 1996.
The validity, reliability, and protocol for the interpolated twitch
technique (ITT) were investigated with isometric plantarflexor and
leg extension contractions. Estimates of muscle inactivation were
attempted by comparing a variety of superimposed to potentiated
evoked torques with submaximal and maximal voluntary contraction
torques or forces (MVC). The use of nerve and surface stimulation to
elicit the ITT were reliable, except for problems maintaining maximal
stimulation with nerve stimulation at 20o plantarflexion and during
leg extension. The interpolated twitch (IT) ratio-force relationship
was best described by a shallow hyperbolic curve resulting in
insignificant MVC prediction errors with second order polynomials
(1.1%-6.9%). The prediction error under 40% MVC was approximately
double that over 60% MVC, contributing to poor estimations of MVC in
non-weight bearing post-immobilized ankle fracture patients. There
was no significant difference in the ITT sensitivity using twitches,
doublets or quintuplets. The ITT was valid and reliable when high
intensity contractions were analysed with a second order polynomial.
Received 29 September 1995; accepted in final form 31 May 1996.
APS Manuscript Number A1054-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96