# A New Flexometric Method to Evaluate Range of Movement: A Validity and Reliability Study
## 4 Discussion  
When physical trainers or coaches introduce a new technique for clinical assessment, an appropriate rationale for their proposals is crucial [13]. This is the first study to use an FM to determine the validity and intra- and inter-rater reliability of SLR and HA. Despite the simplicity of the TMM assessment of ROM, there is a lack of scientific evidence confirming the validity of these procedures compared with different gold standards, such as X-ray analysis, an electrical goniometer, or an inclinometer. Sometimes, the poor validity has been related to the proportional differences in arm and leg lengths between subjects [43; 44; 45]. For instance, some limitations include the TheraBite for measuring the motion of the temporomandibular joint, and specialized devices for measuring the motion of the shoulder [46], forearm [36; 47], wrist [48], hand [49; 50], hip [51], knee [51], foot, and ankle [52; 53]. This study was conducted to evaluate a novel FM by which the hip ROM can be calculated in degrees using the values provided by a flexometer. The method uses TMM and several anatomical lengths and diameters as anatomical references. The FM for field-based tests was designed to estimate ROM and eliminate the effects of individual and developmental differences in leg length and bitrochanter diameter that negatively influence test scores. The main finding of this study was that the FM is a valid and reliable method to assess ROM for both SLR and HA tests. The FM method involves a non-invasive, simple, and easy test, which produced nearly identical ROM results to those obtained by using the WI. The PCC analysis showed an almost perfect correlation between the two methods, suggesting that the FM may be as useful as the WI if used consistently [54]. Moreover, the ICC in our study ranged from 0.97 to 0.99. This range is placed above the upper limit of 0.85 for being considered clinically useful [55] and appropriate when testing single subjects [56]. The MDC90 indicates that a change equal to or greater than the values reported in this investigation would be required over treatment sessions or in research trials to be 90% certain that the change is not due to inter-trial variability or measurement error. Furthermore, FM requires only minimal training, and there is no need for specialized equipment or facilities. The overall reliability and measurement error of this new method were similar to the WI. When we compared the WI results obtained in our study with a previous study measuring a passive straight leg raise test, the results showed similar overall reliability based on the ICC analysis [19]. The inter- and intra-rater reliability were similar for the SLR and HA measurements. Nonetheless, higher SEM and MDC90 were obtained using the WI for the HA inter- and intra-rater reliability. The higher SEM, MDC90, and the widest range of scores in the Bland and Altman plots for the WI in the HA test could be explained by recording with two WIs simultaneously. Figure 4: Bland and Altman plots for INTER: inter-reliability and INTRA: intra-reliability visual illustration. HA: hip abduction test. SLR-R: straight leg raise test for right leg. SLR-L: straight leg raise test for left leg were illustrated. For INTER plots, RA: Rater A and RB: Rater B comparisons were used, where M1: Measure 1, M2: Measure 2, FM: flexometric method, and WI: WIMU system scores were included for each plot. For INTRA plots, M1: Measure 1 and M2: Measure 2 comparisons were used, where RA: Rater A, RB: Rater B, FM: flexometric method, and WI: WIMU system scores were included for each plot. Although the raters who participated in this study had little experience in TMM, WI utilization, and anatomical landmark location, excellent inter- and intra-rater reliability results were obtained. The standardization and training in the process of measurement during several preliminary meetings should be sufficient to minimize interpretation errors.