Validity and Reliability of the New Basic Functional Assessment Protocol (BFA)

The global evaluation of motion patterns can examine the synchrony of neuromuscular control, range of motion, strength, resistance, balance and coordination needed to complete the movement. Visual assessments are commonly used to detect risk factors. However, it is essential to define standardized field-based tests that can evaluate with accuracy. The aims of the study were to design a protocol to evaluate fundamental motor patterns (FMP), and to analyze the validity and reliability of an instrument created to provide information about the quality of movement in FMP. Five tasks were selected: Overhead Squat (OHS); Hurdle Step (HS); Forward Step Down (FSD); Shoulder Mobility (SM); Active Stretching Leg Raise (ASLR). A list of variables was created for the evaluation of each task. Ten qualified judges assessed the validity of the instrument, while six external observers performed inter-intra reliability. The results show that the instrument is valid according to the experts’ opinion; however, the reliability shows values below those established. Thus, the instrument was considered unreliable, so it is recommended to repeat the reliability process by performing more training sessions for the external observers. The present study creates the basic functional assessment (BFA), a new protocol which comprises five tasks and an instrument to evaluate FMP.


Introduction
Assessments are among the main elements for practitioners to make informed and supported decisions for practice, which must be applied with documentary evidence in order to evaluate and improve sport performance [1]. The evaluation of human movement from an objective perspective, may have an impact on the learning and/or training process and, consequently, on performance [2]. In the last 10 years, there has been a change in the screening of musculoskeletal abilities, evolving from muscle and joint analysis towards a more integrated approach [3], in which the emphasis lies on the visual analysis of movement patterns during functional tasks [4].
According to Goodway, Gallahue and Ozmun [5], motor skills/abilities can be assessed from two points of view: product-oriented or process-oriented. Product-oriented evaluation implies Int. J. Environ. Res. Public Health 2020, 17,4845 3 of 34 of the most frequently used tools for an individual's functional assessment. However, it generates opposition, with different authors indicating poor reliability and validity [33], and an inability to predict injury risk [34]. Other authors question the battery punctuation system and suggest that the punctuation method used in FMS does not provide the trainer with specific data about the subject's functionality [35][36][37].
All of these tests contain, in a detailed way, a register of the actions that need to be observed. This register has gone through a process of ratification and reliability in order to verify that it fulfils the aim for which it has been designed, and it is essential that all the tests accomplish this requirement [38]. In this sense, the need to design a test battery, which is capable of assessing fundamental motor patterns (FMP), appears, which is defined as the base and the essence of more complex movements [39] through observational methodology in any type of individual.
Therefore, the aims of the present study were: (a) to design an easy, simple and concise protocol that can be carried out in a field-based context to provide sport science experts with information about the quality of movement in fundamental motor patterns that can be executed by any individual; (b) to analyze the validity and reliability of the instrument created for the analysis of these fundamental patterns of motion.

Design
This study was designed in order to examine the validity and reliability of a new protocol that assesses basic functionality in five different movement patterns. First of all, the instrument was created. The study began with the selection of five tasks that would serve for the evaluation of different basic patterns of motion; all of them have been already studied in the scientific: Over Head Squat (OHS) [40]; Hurdle Step (HS) [11]; Forward Step Down (FSD) [41]; Shoulder Mobility (SM) [42] and Active Stretching Leg Raise (ASLR) [42] (Appendix A). The test selection criteria were the following: (a) having bibliographical backing available as an individual task; (b) it responds from the human motion perspective as FMP, that is, it is the basis of more complex movements, permitting the possibility of execution without materials; (c) its combined performance may provide us with information about the individual's global functional condition.
Once the five tests had been established, a list of compensations that the body can produce when performing each of the established movements was created. The list of compensations that had to be detected in each task was developed, taking into account the scientific literature that relates injury risk with incorrect motor manifestations (for instance, knee valgus, pelvis side inclination or similar manifestations). Once the list of manifestations for observation was proposed, during the second stage of the process, ten qualified judges were asked to make a qualitative and quantitative assessment of the instrument. In order to do that, a document including all the proposed variables for each of the tasks was elaborated, as shown in Table 1, which contained three sections per variable for the judges to evaluate: definition (description of the items); belonging degree (if the variable is considered suitable or not for its inclusion inside the task); information collection and punctuation (if it is considered to be opportune or not in the punctuation system). The screening was accomplished by means of a Likert type quantitative scale from 1 to 10, and extra space was also provided in case the general qualitative evaluation of any element was required. Judges were given a 15 day deadline for completing the document. Using the information gathered from the qualified experts during their first review, some items were modified in their definition as they did not fulfil the minimum value required and some adjustments were conducted, such as the inclusion of the two new items in the suggested categories by the different experts. At the third phase of the assessment process, a new report was written and the same group of qualified judges was asked to elaborate a qualitative and quantitative evaluation of the different items. At this stage, the purpose was to verify the degree of belonging of the object of study and the level of accuracy of the different categories and items. A 15 day deadline for filling out the document was established again. Subsequently, the internal assessment was calculated once again using the data that were extracted after the second revision was completed by the qualified judges. After their second analysis, the list of variables remained permanently established and closed.
At the fourth stage, the reliability of the tools was calculated. This process required the training of six observers that were external to the validation process, for this was held as a training session and two sessions where the reliability study was planned-each of the sessions were 120 min each. The first session was focused on explaining the categories and their codification to let the observers become familiar with them, and then on carrying out a training class for the observers through real situations. At the second session, each observer completed the Basic Functional Assessment (BFA) with the same case, which was redone at the third session 15 days later. The Kappa of Cohen index was calculated for inter-observer and intra-observer reliability of the tool. Reliability within the same observer or intra-rater reliability (a case studied by the same observer in different occasions), was calculated by means of correlating the results from the first observation (at the second session) with those from the second observation (at the third session). Reliability among observers (inter-rater reliability) was estimated by correlating the results from observer 1 with the results from observers 2, 3, 4, 5 and 6, successively with all six participating observers. This process among the observers was completed with the results both from the first and the second monitoring sessions, respectively.
At the fifth and final phase of the assessment process, taking into account all the collected data from the previous stages and doing the necessary adjustments, the process was finalized with the creation of the basic functional assessment (BFA) as an observational tool to evaluate FMP, designed so that it can be undertaken in a minimal amount of time and without the need of using expensive materials. A great step on injury prevention is to concentrate the existent resources in large towns where there are limited amounts of time and resources, as it is in the case of juvenile leagues, state school systems, minor sports clubs, etc. [43].

Participants
Firstly, a total of ten qualified judges, four women and six men, aged between 30-38 years old, participated in the study. All of them were experts in the matter, with a minimum experience in functional assessment of ten years. Although the majority were doctors of Sport Sciences, three guidelines were established, from which at least one had to be fulfilled: (a) to have a degree in Sport Sciences; (b) to have more than five years of experience in functional evaluation both for sportspeople and for non-sportspeople; (c) be currently active in the training/physical therapy professional environment. Secondly, six external observers to the process of validation-two women and four men-between the ages of 21-25 years old, were trained to perform the BFA and participated in the study of reliability. Three of them were students of the last course of the Grade of Sciences of Sport and the other three had already finished the grade and they were students of a Master's degree of investigation in Sciences of Sport. The inclusion criteria for the external observers were: (1) to be a student or to have finished the Grade of Sport Sciences; (2) to attend the training class that took place during the first session.

Variables
In order to have the observational tool elaborated and assessed by the eight experts, two types of variables were essential-calculation variables and the categorical variables.
For the evaluation of the content, the qualified judges estimated the value of the "Belonging" and "Definition" sections from each variable by means of a Likert type quantitative scale from 1 to 10. In case it was necessary, there was also an additional section for a possible general qualitative assessment of each item available. When referring to the categorical variables, each movement involved in the execution of every proposed functional test was taken as a unit of measurement, taking into account three different aspects: the plane from where the observation should take place (sagittal plane, anterior frontal plane and posterior frontal plane); the body area that is observed, which is composed by several items making reference to different body areas (thorax, femur, knee, foot, hip, pelvis, arms, lumbar, cervical, etc.); the type of movements that can be observed and what provides the information about compensations being compensation movements (external and internal rotation, pelvic tilt, valgus, varus, heel lift, etc.). These movements were assessed in both the right and left extremities.

Statistical Analysis
So as to get the validity of the observational tool through the process that was carried out by qualified judges, the validity of content index was determined by calculating the coefficient of Aiken's V [44] using the following equation: V = x−l k . This equation takes into account the number of items, the number of judges, just like the range of assessment for each item; allowing us to check if the obtained magnitude is optimal in terms of content validity in the different items. X is the mean of the judges' marks, l is the minimum scale score and k is the scale range that was used. In order to reject the void hypothesis (V0), the significance level was 0.69. Items whose mean values were below 0.69 were eliminated. The items that had mean values between 0.69 and 0.80 were modified, while those items whose values were above 0.80 did not change.
For the reliability analysis, Cohen's Kappa value [45] was used, the values were classified using the following criteria: trivial (0.1), small (0.1-0.3), moderate (0.3-0.5), large (0.5-0.7), very large (0.7-0.9) or practically perfect (0.9). The statistical analysis was performed using IBM SPSS Statistics for Windows (version 24.0) (IBM Corp, Armonk, NY, USA). Table 2 shows the final compensations reviewed by the expert judges for each of the test. Finally, after the modifications of some of the variables, such as the inclusion of cervical flexion/extension in the OHST test, suggested by the experts. The battery remained composed in the following way: OHST was composed of a total 15 compensations, HST and FSDT match coincided with a total of 17 compensations, SMT test 3 types of compensations and finally ASLR with 10 compensations. All of them are evaluated bilaterally, clearly differentiating whether compensation is made in the right or left hemisphere of the body or on both sides.                                    Table 3 shows the results of the validity of the variables after the second review of the expert judges. The table shows the validity data for the OHS task where all of the items obtained optimal values in terms of belonging for its inclusion; however the item, excess thoracic kyphosis, did not obtain a value suitable for its definition and should be improved.   Table 3 shows the results of the validity of the variables after the second review of the expert judges. The table shows the validity data for the OHS task where all of the items obtained optimal values in terms of belonging for its inclusion; however the item, excess thoracic kyphosis, did not obtain a value suitable for its definition and should be improved.   Table 3 shows the results of the validity of the variables after the second review of the expert judges. The table shows the validity data for the OHS task where all of the items obtained optimal values in terms of belonging for its inclusion; however the item, excess thoracic kyphosis, did not obtain a value suitable for its definition and should be improved.   Table 3 shows the results of the validity of the variables after the second review of the expert judges. The table shows the validity data for the OHS task where all of the items obtained optimal values in terms of belonging for its inclusion; however the item, excess thoracic kyphosis, did not obtain a value suitable for its definition and should be improved.   Table 3 shows the results of the validity of the variables after the second review of the expert judges. The table shows the validity data for the OHS task where all of the items obtained optimal values in terms of belonging for its inclusion; however the item, excess thoracic kyphosis, did not obtain a value suitable for its definition and should be improved.   Table 3 shows the results of the validity of the variables after the second review of the expert judges. The table shows the validity data for the OHS task where all of the items obtained optimal values in terms of belonging for its inclusion; however the item, excess thoracic kyphosis, did not obtain a value suitable for its definition and should be improved. Table 3. Assessment of Aiken V by ten experts of the proposed variables for OHS.

Variables
Definition The planes from which the different offsets were observed are also established. OHST, HST and FSDT are observed from three planes-front, sagittal and back. SMT is observed from the sagittal plane and back, and ASLR is observed only from the sagittal plane. The images detail which points we need to look at to detect the compensation. Table 3 shows the results of the validity of the variables after the second review of the expert judges. The table shows the validity data for the OHS task where all of the items obtained optimal values in terms of belonging for its inclusion; however the item, excess thoracic kyphosis, did not obtain a value suitable for its definition and should be improved.  Table 4 shows the validity data for the HS task-all the items obtained optimal values both in their definition and in their belonging.  In Table 5 we find the validity data for the FSD task-all the items obtained optimal values both in their definition and in belonging. The data in Table 6 refer to the SM task-all their items obtained optimal values regarding belonging; however, the data show that definitions are not optimal and should be improved for its inclusion. Finally, Table 7 shows the data of the variables corresponding the ASLR task-all these variables obtained optimal values in terms of their belonging and their definition. Bearing in mind the results of Tables 3 and 6, in Table 8 shows a new definition is proposed for variables that have not met the minimum value. These variables have obtained the maximum value in terms of belonging, so we considered that they should be included in the observation sheet, modifying for its definition. Table 9 shows the results of intra-observer reliability, calculated on each test and together as a single battery. The results obtained are dispersed, the SM task being the only one that obtains a practically perfect reliability with a Kappa value of 1 in the three observers, while the contrary occurs with the FSD task, where a small reliability appears (0.1-0.3). We also found a trivial value (0.1) in the HS task. The reliability data of the battery as a whole are also shown, where only one of the observers attained very large reliability (0.75). In the thoracic spine there appears a greater convexity, which increases the dorsal curvature and appears in dorsal hypokyphosis, seen from the sagittal plane The convexity of the dorsal curve increases excessively during the movement, seen from the plane sagittal

SM
Winged scapula, right arm flexion and left external shoulder rotation; back plane When the left arm, in the external shoulder rotation, looks for the right hand that makes the internal shoulder rotate and the lower peak of the right scapula is shown, viewed from the front/back plane Pronunciation of the right scapular peak when the left arm is in external shoulder rotation and the right is in internal rotation, seen from the front/back plane Winged scapula, left arm flexion and right external shoulder rotation; back plane When the right arm, in the external shoulder rotation, looks for the left hand that makes the internal shoulder rotate and the lower peak of the left scapula is shown, viewed from the front/back plane.

Pronunciation of the left scapular
peak when the right arm is in external shoulder rotation and the left is in internal rotation, seen from the front/back plane Excess lumbar lordosis, right arm flexion and left external shoulder rotation; sagittal plane When the movement is performed with the left arm in shoulder flexion and external rotation, it looks for the left hand and the lumbar area shows hyper lordosis, seen from the sagittal plane.
The concavity of the lumbar curve increases excessively during the movement when the left arm is in external rotation and the right is in internal rotation, seen from the sagittal plane.
Excess lumbar lordosis, left arm flexion and right external shoulder rotation; sagittal plane When the movement is performed with the right arm in shoulder flexion and external rotation, it looks for the left hand and the lumbar area shows hyper lordosis, seen from the sagittal plane.
The concavity of the lumbar curve increases excessively during the movement when the right arm is in external rotation and the left is in internal rotation, seen from the sagittal plane Cervical protraction, right arm flexion and left external shoulder rotation; sagittal plane When the movement is performed with the left arm in shoulder flexion and external rotation, it looks for the right hand and cervical ante pulsion appears, seen from the sagittal plane The pterygoid vertical line is more advanced than at the start of motion when the left arm is in external rotation and the right in internal rotation, seen from the sagittal plane Cervical protraction, left arm flexion and right external shoulder rotation; sagittal plane When the movement is performed with the right arm in shoulder flexion and external rotation, it looks for the left hand and cervical ante pulsion appears, seen from the sagittal plane The pterygoid vertical line is more advanced than at the start of motion when the right arm is in external rotation and the left in internal rotation, seen from the sagittal plane The values of inter-observer reliability were made only from the (BFA) battery and at both observation periods, showing different values in each period (Table 10). The first observation obtained moderate-small reliability (0.1-0.5) and the second observation obtained small reliability (0.1-0.3). Some large inter-observer reliability values were obtained (0.5-0.7), one in the first observation and two in the second observation. Finally, the BFA battery shows a intra-inter observer reliability of moderate-small.

Discussion
The objectives of the present study were to design and to analyze the validity and the reliability of an observational sheet, aimed at drafting a Basic Functional Assessment battery (Table A1) which is able to provide us with information about the quality of movement in PMF. The results showed that the BFA is considered valid for its use in detecting alterations in PMF. It also showed a low to moderate intra and inter-observer reliability for BFA. Kappa values presented higher values in isolated tests in terms of intra-observer reliability. Table 2 exhibits the final manifestations that were revised by the expert judges for each of the tests. A total of 61 manifestations were established, of which 53 of them must be evaluated in a unilateral way. Body asymmetry may be associated with a higher presence of injuries [46,47]. Some authors report the importance of asymmetry assessment in their studies [20,29,35,48]. Some proposed modifications by the experts were made, such as including cervical extension and flexion. This compensation has been highlighted within the back squat correct technique [10,49]. The group of experts considered keeping a great number of the variables and the proposed definitions. Some of these variables are studied in other tasks (e.g., knee valgus/varus, heel lift, foot pronation/supination, lumbar kyphosis/lordosis, pelvic tilt). Kritz [26] uses them especially when assessing the following tasks: squat; lunge and twist; single leg squat. Similarly, so do Bennett et al. [50], who employ these variables particularly in squat and overhead reach test evaluations. In other studies, the use of other variables that have also been accepted by the experts are found, such as the manifestation of the arms falling forward, utilized within the overhead assessment [35,50]. Padua et al. [43] apply the internal/external rotation of the feet for the jump-landing task evaluation as an injury predictor. Myer et al. [49] describe, in a similar way, the pelvic tilt during back squat. Park et al. [41] use the FSDT test, and its assessment is based on the criteria that coincide with some of those suggested (e.g., torso movement, aligned knees, pelvic tilt and rotation) and they also bear in mind the external pelvic rotation. However, as opposed to how it is contemplated in BFA, this last variable is evaluated by means of using a dynamometer. In Cook et al. [4], for FMS battery during an ASLR test, some advice for their execution are proposed that coincide with some of the suggested variables in this test-the external rotation of the leg that remains on the ground and laid out knees.
Nevertheless, not all definitions were accepted by the experts. In the OHST test, the manifestation-an excess in thoracic kyphosis-seen from the sagittal plane, did not get a valid definition. Myer et al. [49] emphasize this manifestation and claim that the thoracic spine should preferably be extended and rigid. In the case that it is not able to stand, it may suggest weakness in the spinal erectors, trapezius and rhomboid, as well as an upper crossed syndrome. Due to the fact that its inclusion within the test has been considered accurate and valid and it is considered an important manifestation in order to include it in the OHST evaluation, since it may provide with valuable information about poor PMF, a new definition has been proposed, as shown in Table 4. In the SMT test, all the manifestations-winged scapula, lordosis excess and cervical protraction-obtained excellent belonging validity; however, their definitions were not suitable. In spite of this, the SMT test was considered to be included within the BFA. In a study published by Larsen et al. [51] it was corroborated that simple visual observation methods to assess the scapular function present a better reliability compared with other types of more complex measuring. The SMT test is used to evaluate the functionality of the upper part of the body [52]. Manifestations proposed for SMT are considered suitable to discover poor motion patterns within the upper extremities. The presence of winged scapulars could provide us with information about the existence of other alterations that may limit the scapula-humeral functionality. In a study of cases which were published by Martínez Bermudez et al. [53], it was found that all the Parsonage-Turner syndrome cases showed the presence of winged scapula. Other studies reported the same data [54,55]. Concerning the manifestation of lordosis excess, Kritz [26] points out the importance of debating the role of the lumbar area in upper-body movement tasks, since the lumbar area is responsible for stabilizing the spine during upper-body movement tasks. If there is not proper lumbar stabilization, the needed strength for the shoulder to work may be compromised [56]. Since we are dealing with manifestations that may provide us with valuable information about poor PMF in an upper member, new definitions have been proposed, as shown in Table 4. All the suggested definitions in Table 4 must be re-evaluated by the experts, so as to obtain a validity value in the suitable definition and, therefore, include them within the BFA protocol.
Another objective of this study was to test the intra-and inter-observer reliability of the BFA. Intra-observer reliability was conducted individually for each test and combined as a BFA battery; meanwhile inter-observer reliability was directed only in a combined way.
All the values were considered inferior to those that were seen as suitable, showing a BFA low-to-medium reliability. Although a specific limit to determine if the reliability coefficient is high or not does not exist, a coefficient higher than 0.70 is considered acceptable [57], reaching this value on very few occasions. In other studies, in which observational methodology as an assessment system is used, close values to those obtained ones found. Rogers et al. [58] obtained a deficient intra/inter-observer reliability in the AAA battery when carrying it out among Australian sub-elite football players. Weir et al. [59], following bibliographical recommendations, chose six core stability evaluation tests and showed a deficient intra/inter-observer reliability. In the same line, we found Inovero et al. [27], who also displayed a deficient intra/inter-observer reliability among university volleyball athletes. Dekkers et al. [60] analyzed the Observable Movement Quality scale reliability among children between the age of six months and six years, and they obtained moderate inter-observer reliability results.
The results obtained in BFA reliability may be due to certain limitations that the study exhibit, such as the fact that the observers were Sport students only, who had little experience with this type of methodology. Facing this limitation, it is interesting to establish strategies to improve BFA reliability, such as: (1) Increasing the training among the observers. Inovero et al. [27] conducted a validation process for the MSC test by only carrying out two formative sessions and obtained similar results to ours with a low reliability. In this manner, Rogers et al. [58] executed a reliability process for the AAA battery, having two formative hours and obtaining low reliability results. It is likely that a coordinated and standardized formation may help improve the utility of the system among evaluators [36,61].
(2) Carrying out the study relying on the expert and novice observers' collaboration. The different values obtained in each of the individual tests could be due to the familiarity and experience that the observers have in each of the tests. In a study published by Bennett et al. [50], the impact of the evaluator's experience within the reliability data in a Movement Screen battery was determined. High reliability data were obtained among evaluators, decreasing these values among the novice evaluators and also pointing out the importance of a standardized formation for inexperienced evaluators, since the learning associated with the movement quality assessment leads to a more consistent punctuation [7]. Weeks et al. [62] also showed the importance of the observer's experience as, in their study they obtained higher reliability data than those who had more experience.
On the other hand, the observational sheet was designed with a punctuation system in which the BFA maximum result may reach 76. If the subject manifests a compensation it will count as "1 point", if it does not manifest any compensations it will count as "0 points" and it quantifies as the addition of: 14 possible errors of individual movement for the OHST; 22 for the HST; 22 for the FSDT; 6 for the SMT; 12 for the ASLRT. Each of the tests is marked individually and, joining all of them, the global punctuation is obtained for the person's motion quality. This punctuation system has certain advantages, since it allows us to perform comparatives during the re-evaluation, as well as permitting the professionals to execute data analysis about the movement quality and other aspects about the athlete's physical development [63,64]. The use of a numerical marking system has been debated among authors. During a systematic revision [2] it was shown that the general punctuation of poor quality of movement is associated with a higher risk of injury in the lower extremities. Mann et al. [65] demonstrate that a total punctuation may be used in a more reliable way than an individual one when assessing movement. Despite the fact that the global punctuation system has been used in research, there is scientific evidence that contradicts this marking system [33]. Bonazza et al. [37], in a systematic revision about FMS, show a low inner validity in systems that employ a numerical marking system, and declare that the results must focus on individual punctuation instead of a global mark. Kazman et al. [66] maintain the idea that, when employing the numerical marking system, every test must be graded as a one-dimensional construction. Between both perspectives lie O'Connor et al. [36], who do not recommend the use of a general numerical marking system as the only risk of injury identification method.
The study has some limitations, such as the lack of training sessions for the reliability process. It is likely that, by performing a more extensive training, observers will be more familiar with the BFA assessment process and obtain better reliability values of the instrument. Therefore, it is considered of importance to repeat the intra and inter-observer reliability process, persevering previously commented characteristics since a reliable observational tool among observers is an important aspect. Having consistency among observers indicates that the different people may employ the instrument and obtain similar results [35].
Results suggest that BFA may have potential to establish motion quality in different subjects. For future research lines, it is recommended to investigate reliability and open other lines, such as their use in the detection of injury risk among amateur sportspeople, seeing as it consists of a movement quality assessment that does not require specific tools from a laboratory. This is also interesting for its application in sport centers as an initial observational form to establish different action protocols, allowing for the individualization of the user during training.

Conclusions
The present study creates the basic functional assessment (BFA), a new protocol which comprises five task and an instrument to evaluate a selection of five fundamental motor patterns (FMP). The BFA has been designed to be an easy, simple and concise protocol that can be carried out in a field-based context, to provide sport science experts with information about the quality of movement in FMP that can be executed by any individual and are the basis to develop more complex movements.
The previously described tool is considered as valid so it is able to accept its use as a tool for the Basic Functional Assessment. It has been shown that the tool is not reliable in its measure. This study has some limitations, such as the lack of training sessions of observers for the reliability process. Therefore, the reliability process must be repeated, taking into account the limitations of the study. This process can be considered as a future line of research, as well as working on other lines, such as using BFA in detecting the risk of injury and obtaining battery data based on the field. Funding: This study is part of the project entitled "Study of risk of injury in young athletes through artificial intelligence networks" (DEP2017-88775-P), funded by the Spanish Ministry of Science and Innovation and Universities, the State Research Agency (AEI) and the European Regional Development Fund (ERDF). This research was funded by a predoctoral grant awarded by the Ministerio de Educación, Cultura y Deporte (grant number: FPU15/05200) and a predoctoral grant awarded by the Ministerio de Ciencia, Innovación y Universidades (grant number: FPU18/00702).

Conflicts of Interest:
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript or in the decision to publish the results.

Appendix A
The examiner will indicate these instructions to the subject prior to the performance of each task, so that the task is performed from a standardized point of view and in the same conditions for all subjects. The indications will be different for each task.
Overhead squat test: • Separate the feet (barefoot) to be shoulder-width apart • Place the second toe facing forward in line with your knee • Lift arms up, as if you would like to touch the ceiling (or the sky) • When I say "ready, go", crouch your bottom down as much as you can to the ground • You will perform two repetitions for each side If the subject asks "is it squat?" you have to answer: "you must lower your bottom to the ground as much as possible." Hurdle step test: • Climb on a step (10-20 cm high) and put your bare feet together • Cross your arms over your chest • When I say "ready, go" lift your right/left knee as much as you can without falling and keep it up until I tell you. • You will perform two repetitions for each side Forward step-down test: • Climb on a step (10-20 cm high) and put your bare feet together • Cross your arms over your chest • When I say "ready, go" carry your right/left heel down and forward as much as you can without falling • You will perform two repetitions for each side Shoulder mobility test: • Spread your arms and keep them horizontally (in cross) and place your thumbs inside the other fingers. • When I say "Ready, go" lift your right arm above your head and bring the left arm below until both wrists come together in your back. • You will perform two repetitions for each side Active straight leg raise: • Lie on your back with your legs extended and your arms stood on the floor a bit separated from the body.

•
When I say "ready, go" lift your right leg fully extended as much as you can • You will perform two repetitions for each side Appendix B Displacement of the right/left knee in the front plane during movement, so that the distance between the two knees is reduced by staying closer to the midline of the body at the end of the movement

View Variable Definition Score
Knee valgus [62] Displacement of the right/left knee in the front plane during movement, so that the distance between the two knees is reduced by staying closer to the midline of the body at the end of the movement

Internal rotation foot
Turning the foot on the longitudinal axis until the phalanges of the second right/left toe are oriented in the medial direction □ Yes = 1 □ No = 0 Knee valgus [62] Displacement of the right/left knee in the front plane during movement, so that the distance between the two knees is reduced by staying closer to the midline of the body at the end of the movement Knee varus [67] Displacement of the right/left knee in the front plane during movement, so that the distance between the two knees is increased to the midline of the body at the end of the movement Knee varus [67] Displacement of the right/left knee in the front plane during movement, so that the distance between the two knees is increased to the midline of the body at the end of the movement Thorax rotation [68] Rotation of the trunk to the right/left of the observer Knee varus [67] Displacement of the right/left knee in the front plane during movement, so that the distance between the two knees is increased to the midline of the body at the end of the movement Thorax rotation [68] Rotation of the trunk to the right/left of the observer Knee varus [67] Displacement of the right/left knee in the front plane during movement, so that the distance between the two knees is increased to the midline of the body at the end of the movement Thorax rotation [68] Rotation of the trunk to the right/left of the observer □ Yes = 1 □ No = 0 BP Foot pronation [69] A fall of the plantar arch is observed in the right /left midfoot area Foot supination Overly pronounced right/left □ Yes = 1

Excess lumbar lordosis
The concavity of the lumbar curve increases too much during movement Lumbo-pelvis dissociation loss [41] Lumbar neutral curvature disappears □ Yes = 1 □ No = 0

Excess lumbar lordosis
The concavity of the lumbar curve increases too much during movement Excess thoracic [69] The convexity of the dorsal curve increases too much during movement Excess thoracic [69] The convexity of the dorsal curve increases too much during movement Arms fall to the front [71] The right/left hand fingers pass the vertical line drawn from the toes, so that the right/left arm is not aligned with the trunk □ Yes = 1 □ No = 0

Cervical extension
The concavity of the cervical curve increases too much during movement □ Yes = 1 □ No = 0

Cervical flexion
The concavity, of the cervical curve is lost too much during movement, the face is oriented in a flow direction Arms fall to the front [71] The right/left hand fingers pass the vertical line drawn from the toes, so that the right/left arm is not aligned with the trunk Excess thoracic [69] The convexity of the dorsal curve increases too much during movement Arms fall to the front [71] The right/left hand fingers pass the vertical line drawn from the toes, so that the right/left arm is not aligned with the trunk Excess thoracic [69] The convexity of the dorsal curve increases too much during movement Arms fall to the front [71] The right/left hand fingers pass the vertical line drawn from the toes, so that the right/left arm is not aligned with the trunk □ Yes = 1 □ No = 0

Cervical extension
The concavity of the cervical curve increases too much during movement □ Yes = 1 □ No = 0

Cervical flexion
The concavity, of the cervical curve is lost too much during movement, the face is oriented in a flow direction

Cervical flexion
The concavity, of the cervical curve is lost too much during movement, the face is oriented in a flow direction

Cervical extension
The concavity of the cervical curve increases too much during movement □ Yes = 1 □ No = 0

Cervical flexion
The concavity, of the cervical curve is lost too much during movement, the face is oriented in a flow direction  Displacement of the right/left knee in the front plane during movement farther to the midline of the body at the end of the movement.
Knee valgus support [69] Displacement of the right/left knee in the front plane during movement by staying closer to the midline of the body at the end of the movement Pelvis tilt [70] Opposite pelvis drops in the front plane relative to right/left hip flexion Pelvis rotation [70] Rotation of the hip staying aside, more moved forward than other Pelvis tilt [70] Opposite pelvis drops in the front plane relative to right/left hip flexion Pelvis tilt [70] Opposite pelvis drops in the front plane relative to right/left hip flexion Pelvis rotation Rotation of the hip staying aside, □ Yes = 1 Table A1. Cont.

View Variable Definition Score
Pelvis rotation [70] Rotation of the hip staying aside, more moved forward than other Pelvis tilt [70] Opposite pelvis drops in the front plane relative to right/left hip flexion □ Yes = 1 □ No = 0 Pelvis rotation [70] Rotation of the hip staying aside, more moved forward than other Thorax rotation towards the hip in flexion [72] Rotation of the thorax toward the right/left support leg Thorax rotation towards the hip in flexion [72] Rotation of the thorax toward the right/left support leg Thorax rotation opposite hip in flexion [73] Rotation of the thorax in the opposite direction to the right/left support leg Thorax rotation towards the hip in flexion [72] Rotation of the thorax toward the right/left support leg Thorax rotation opposite hip in flexion [73] Rotation of the thorax in the opposite direction to the right/left support leg Thorax rotation towards the hip in flexion [72] Rotation of the thorax toward the right/left support leg Thorax rotation opposite hip in flexion [73] Rotation of the thorax in the opposite direction to the right/left support leg □ Yes = 1 □ No = 0 Thorax movement [73] Movement of the thorax in several directions when flexing the right/left hip □ Yes = 1 □ No = 0 BP Support foot A fall of the plantar arch is observed in the right/left support □ Yes = 1 Table A1. Cont.

View Variable Definition Score
BP Support foot pronation [70] A fall of the plantar arch is observed in the right/left support midfoot area Thorax movement [73] Movement of the thorax in several directions when flexing the right/left hip □ Yes = 1 □ No = 0 BP Support foot pronation [70] A fall of the plantar arch is observed in the right/left support midfoot area □ Yes = 1 □ No = 0 Support foot supination [41] The Plantar arch of the right/left midfoot support is excessively pronounced Pelvis tilt [70] Pelvis drop in the front plane to the side of the leg in right/left □ Yes = 1 Table A1. Cont.

View Variable Definition Score
Pelvis tilt [70] Pelvis drop in the front plane to the side of the leg in right/left extension Internal rotation extended leg [71] Right/left extended leg rotation on the longitudinal axis, leaving the extended leg facing into the medial line of the body

View Variable Definition Score
Thorax movement [70] Movement of the thorax in several directions when lengthening right/left leg Thorax rotation opposite the leg supported [71] Rotation of the thorax opposite direction the right/left support leg

View Variable Definition Score
Extension thoracic, hip flexion The thoracic area extends, keeping the thorax faced in cranial sense when the right/left leg is raised