Despite the Sahrmann test scores and TrA thickness at rest bothbeing significantly less in the frequent (weekly) ETAP group nosignificant relationship was found between these two variables.Although designed to be a measure of TrA, the Sahrmann test,which sequentially increases the demands of the trunk muscula-ture, may in fact require activation of other abdominal muscles,including internal and external oblique, as well as rectus abdomi-nus. This may explain lack of a strong positive association observedbetween the Sahrmann test and TrA thickness change which maybe attributed to the involvement of other abdominal muscles dur-ing the Sahrmann test, rather than only TrA. Previous literature hasidentified internal oblique as another primary muscle involved inspinal and core stability,whose activation with the abdominaldraw in manoeuvre has been demonstrated with magnetic reso-nance imaging.20The lack of correlation with TrA thickness changemay be explained by the internal oblique providing spinal stabilityin addition to TrA whilst performing the Sahrmann test. The amountof core stability training performed by participants may also havecontributed to the Sahrmann test score.It must be acknowledged that the findings of this study arepreliminary. Some of the differences between the groups werenot consistent such as the lack of difference for Sahrmann testscores between the yearly and monthly groups. There are severalpotential causes for these inconsistencies that should be consid-ered by practitioners intending to apply the results of the study.The small sample sizes for each group may have contributed tothis as the study was powered for ultrasound measurements notthe Sahrmann test. However, there were also discrepancies in thefindings for this variable with resting TrA thickness highest in theyearly group but this may have been due to the higher proportionof males and the highest training volume in this group, despite theabsence of a significant difference between the groups for thesevariables. Plausibly a limitation may have been due to the relianceon the questionnaire for recall of ETAP. The accuracy of ETAP recallover a year can be questioned, as previous research into physi-cal activity recall over 12 months has observed only acceptablevalidity,and this would subsequently have affected group allo-cation. Other limitations for the current study in addition to therelatively small sample sizes for each group include an elementof non-homogeneity within and between the groups in regard toage, training volume, type of usual running activity performed andpotentially athlete level which may all be factors that affect bothTrA thickness or frequency of ETAP.