Methodological issues with the assessment of voluntary activation using transcranial magnetic stimulation in the knee extensors

  1. lisa Schäfer
  2. Aaron Greenhouse-Tucknott

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Description: The assessment of voluntary activation of the knee extensors using transcranial magnetic stimulation (VATMS) is routinely performed to assess the supraspinal function. Yet methodological scrutiny of the technique, whether used at rest or more crucially following exercise, is scarce. The aim of the present study was to examine face validity and reliability of VATMS and its two main determinants (superimposed twitch during a maximal voluntary contraction [SIT100%] and estimated resting twitch [ERT]) at rest and following intermittent isometric fatiguing exercise. Responsiveness of VATMS to the exercise intervention was also measured. The findings indicated issues regarding the accuracy of ERT and suggested a three-point relationship should not to be used to determine ERT. Reliabilities for VATMS, SIT100% and ERT were acceptable at rest but much weaker post-exercise (especially for SIT100%). Despite statistically significant changes in the main neuromuscular variables post-exercise (P < 0.05), the effect on VATMS was smaller than the smallest detectable change in 18 of the 20 individual tests performed, and for the whole sample on one of the two visits, when post-exercise reliability was considered. Consequently, these changes were not deemed detectable. Finally, neuromuscular fatigue was present following the neuromuscular assessment itself (NMA) at rest, and recovery was evidenced during the post-exercise NMA. These findings challenge the face validity of this routinely used protocol.

License: CC-By Attribution 4.0 International

This project represents an accepted preprint submitted to SportRxiv . Learn more about how to work with preprint files. View preprint


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