## 4 Discussion
Other FMS tasks were weakly (the hurdle step) or not (in-line lunge, active straight-leg raise, shoulder mobility, and trunk stability push-up) related with tasks included in the newly developed HLLMS tool. The hurdle step is used to assess functional mobility and stability of lower limb joints, whereas shoulder mobility and trunk stability push-ups are used to assess the shoulder range of motion and trunk stability during upper-extremity motion, respectively [6; 7]. Thus, in the present study, the correlation results were expected. It may only be surprising that no relationship was detected between the in-line lunge (FMS) task and the HLLMS tasks, as the in-line lunge by [PERSON] et al. [6; 7] is described as assessing hip and ankle mobility and stability, quadriceps flexibility, and knee stability. Considering that the HLLMS was developed to specifically assess control of the hip, pelvis, and lower limb joints [5], a certain degree of relationship with the in-line lunge (FMS) was expected. Movement screening tools are characterized by: (a) assessment of movement quality [11]; (b) assessment of physical performance; and (c) identifying painful movement during movement tasks [6; 7]. Additionally, it may be worth developing screening tools considering a targeted body part (movement screening tools could be created concerning a specific part of the body). Studies have shown that the FMS is not sensitive for detecting altered movement patterns in lower limb joints of footballers [21; 40; 41]. It may be partly due to the FMS containing some tasks not directly related to the lower limb, such as the shoulder mobility or the trunk stability push-up. In addition, the FMS lacks unilateral weight-bearing tasks, which are typical in sports [42], and seems more likely to show compensations relevant to bilateral tasks [43]. From this perspective, development of the HLLMS to focus on altered movement patterns and asymmetry, specifically of the pelvis and lower limbs, was warranted, because of the high incidence of hip and groin pain in injuries in athletes [15; 16; 17]. The HLLMS does not require any equipment, so it is therefore quick, easy, and cheap to use. It can also be used as an assessment in return to play, by conducting testing at the start of a season then following injuries. Additionally, the HLLMS is useful to detect modifiable movement compensations and direct referral for primary, secondary, and tertiary prevention in the context of injury and OA [5]. The present study had a number of limitations. Firstly, the present findings may only be applied to the group examined (male elite adolescent football players) and generalization to athletes involved in other sports or to female footballers cannot be assumed. Secondly, the study included a relatively small sample size, although other studies using the FMS and/or functional tests used similar sample sizes [21; 28; 44; 45; 46; 47]. Thirdly, although the HLLMS showed very good intra-rater and inter-rater reliability in youth male football players [5], the reliability of the assessor conducting the HLLMS protocol for this study was not examined. However, the HLLMS data were collected by an experienced and qualified physiotherapist (who also attended FMS course) who was not informed of this study aim. To minimize bias being introduced during the data collection process, the FMS and the HLLMS data were collected by two separate raters, ensuring the therapists collecting the data were not aware of previous FMS/HLLMS scores, preventing the investigator's test interpretation being influenced. However, we are unsure whether past experience with the FMS of the physiotherapist assessing the HLLMS may affect the study results in some way. Automatic systems used to assess HLLMS and FMS may be needed in order to avoid bias potentially introduced by the raters. Previous research has been conducted to create an automated system to score the FMS in order to make the tool more objective [48; 49; 50]. However, the results were inconclusive.