Rehabilitation Research and Practice 5 Table 3: Rating criteria for runner pose test: good and poor stability Runner Pose Test Good 1. Overall Impression Smooth, good-quality movement General control 2. Weight Distribution Minimal translation of centre of mass 3. Pelvic Alignment Hip dissociation from pelvis—minimal pelvic movement Minimal A-P movement (anterior pelvic tilt) Minimal tilt in frontal plane (ASIS level) 4. Trunk Alignment No rotation of trunk Trunk upright or distribution, and alignment of the lumbar spine or trunk, pelvis, leg, and foot. Characteristics of good and poor performance were described. For rating criteria to have construct validity, the domains of interest must be adequately assessed [44]. The criteria developed in this study comprehensively covered all aspects thought to be important for LPS and built on previous rating criteria for SLS [3, 32, 39]. The criteria developed in this project were also very similar to those developed for step-down test [45]. Thus, there is preliminary evidence for construct validity for the rating criteria. A third step in the development of rating criteria has been described as giving a relative weighting or emphasis to the ﬁnal items included [42]. This was not done in this study. The rating criteria were designed for all items to be combined to achieve the overall rating of LPS rather than to individually rate items or subcategories. This was done to maintain the clinical utility of the criteria as tests that require this may not be as easy or quick to administer [46, 47]. In addition, experienced raters are likely to combine key observations to make an automatic rating [48] based largely on the overall impression of movement quality, and this method of rating is commonly used by physiotherapists [45]. The trustworthiness of a qualitative research process relies on credibility [49]. Credibility is enhanced by the experience and qualiﬁcations of the investigators, member checks, and similarity to previous studies [40]. This study met each of these three principles. First, the members of the focus group were experienced in examining LPS. These well- qualiﬁed clinicians with a mean of 14-year experience in a wide variety of sports would be expected to be able to identify good and poor performance characteristics of LPS. Second, member checks were performed during and after the focus group discussion to conﬁrm the themes that were developed. Each member had the opportunity to individually comment on or suggest changes to the criteria. This mitigated the possible eﬀect of any one member of the group dominating the outcome and ensured that the criteria truly represented Poor Jerky movement Eﬀort to control movement Excessive trunk movement Inability to maintain centre of mass over weightbearing leg Discernible movement of pelvis with the hip—no dissociation Discernable tilt in frontal plane Trunk rotation Forward ﬂexion of trunk Trunk locked in extension the perceptions of LPS of each member of the group. Third, the discussion themes and ﬁnal rating criteria shared some characteristics with rating criteria used in other studies of SLS with the inclusion of assessment of trunk, pelvis, and thigh [3, 32, 39]. The rating criteria developed in this project also included assessment of foot alignment for SLS and DT. Foot function may inﬂuence performance via the closed kinetic chain used in these tests. The lack of evaluation of foot function was discussed as a limitation in a study of the step down test by Crossley et al. (2011) [45]. For these reasons, it is credible that these criteria do represent the characteristics of good and poor stability. The trustworthiness of a qualitative research process also depends on transferability [49], whether the rating criteria are transferable or generalizable to a range of individuals or whether they would have limited application. They are transferable and suitable for the orthopaedic assessment of active male and female adults. The validity of their use as a screening tool, as a means of identifying injury, or a means to assess timing of a return to sport remains to be investigated in prospective injury studies. Their use in other populations such as older adults, elite athletes, children, and populations with neurological conditions also remains to be investigated. Other confounding factors may be introduced in these populations that would reduce the clinical utility of these rating criteria. Qualitative focus group studies have some disadvantages and these are acknowledged as limitations. Disadvantages relate to the role of the facilitator, accurate recording of the discussion, and management of issues of dissent [41]. First, results can depend on the skill of the group facilitator to generate unbiased discussion without inﬂuencing the group to arrive at a predetermined conclusion. The extent to which the group may have been inﬂuenced by the facilitator cannot be determined. Second, inaccuracy of recording of the discussion may inﬂuence the results. However, as discussed above, the notes were read back to the group and each group member had an opportunity to clarify and correct the