Get access

Comparison of interpolation and central activation ratios as measures of muscle inactivation

Authors

  • David Behm PhD,

    Corresponding author
    1. School of Physical Education, Recreation and Athletics, Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7, Canada
    • School of Physical Education, Recreation and Athletics, Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7, Canada
    Search for more papers by this author
  • Kevin Power BKin,

    1. School of Physical Education, Recreation and Athletics, Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7, Canada
    Search for more papers by this author
  • Eric Drinkwater MPE

    1. School of Physical Education, Recreation and Athletics, Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7, Canada
    Search for more papers by this author

Abstract

The objective of this study was to investigate different methods of estimating muscle inactivation, derived from single and multiple voluntary contractions. Ten subjects performed maximal and submaximal leg extensor contractions to determine an interpolation (IT) or central activation ratio (CAR). A superimposed evoked force was compared with the force output of either a voluntary (CAR) or resting evoked contraction (IT ratio), or the ratios were inserted into regression equations (linear, polynomial, exponential). Linear-regression estimates of CAR using doublets and tetanus provided physiologically inaccurate values. Whereas IT ratios using doublets (IT-doublet) and tetanus (IT-tetanus) had a significant difference in only one interaction, IT-tetanus and CAR using a tetanus (CAR-tetanus) estimates provided the most extensive correlation within and between measures. Thus, tetanic stimulation superimposed upon single maximal or multiple contractions seems to provide the most valid measure of muscle inactivation when using the interpolated-twitch technique. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 925–934, 2001

Get access to the full text of this article

Ancillary