title: The intercept method: a novel method for establishing consistency of M-wave recruitment curves.
abstract: The stability of the M-wave is an important component of experimental H-reflex methodology. Despite this importance, there is inconsistency in H-reflex literature on the most valid method of M-wave stability analysis. Further, there is currently no specific method for establishing the stability of an M-wave recruitment curve across various trials within an experiment. Therefore, the aim of this study was to investigate the most appropriate method of M-wave stability analysis for use with the recruitment curve methodology. Twenty-five healthy subjects participated in the study. Four M-wave recruitment curve recordings were made in various static positions that imposed stretch on the posterior structures of the back and leg. Four methods of post-data collection M-wave stability analysis were compared. Although on visual inspection, there was clear evidence of marked alterations to the M-wave recruitment curves between trials in some subject's data, analysis of variance of the Ms/p and Mmax found no significant difference. Evaluation of the percent deviation in Mmax found nine subjects with greater than ten percent deviation in their maximum M-wave across the four trials. The intercept method that utilises analysis of the 95% confidence interval of the intercept of the M-wave recruitment curve slope, excluded eight subjects that demonstrated variation. Comparison of the percent deviation and the intercept method revealed that the intercept method was the most appropriate method for M-wave stability analysis in conjunction with the recruitment curve methodology.
authors.affiliation: Physical Rehabilitation Research Centre, School of Physiotherapy, Auckland University of Technology, Private Bag 92006, Auckland, New Zealand.
authors.forename: J M
authors.initials: JM
authors.lastname: Kerr
authors.forename: A L
authors.initials: AL
authors.lastname: Vujnovich
authors.forename: L
authors.initials: L
authors.lastname: Bradnam
mesh_terms: D000328:Adult; D004576:Electromyography / Q000379:methods*; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology; D008161:Lumbosacral Region / Q000502:physiology; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D012016:Reference Values; D012026:Reflex, Stretch / Q000502:physiology*; D015203:Reproducibility of Results; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods