## 5 Conclusions  
A decrease in postural stability and an increase in core function (i.e., StP) only affected the BLD of peak force, not that of mean force, during isometric elbow flexion. On the other hand, no difference was observed when comparing unilateral D vs. ND movement, with no influence of position or dominance observed when comparing movement D with ND. A greater peak force was also found in SiP D + ND than in BL in both SiP and StP. Finally, unilateral movements (i.e., D or ND) produced lower force values than BL movements (i.e., D + ND or BL).  
Bilateral strength training reduces BLD, whereas unilateral strength training increases BLD [2]. In predominantly bilateral sports, lower BLD or greater bilateral facilitation is associated with enhanced performance. Conversely, in sports where changes in direction or unilateral movements are predominant, greater BLD is associated with greater performance [13]. Therefore, it is up to each coach to decide what is more interesting to improve the performance of their athletes.  
The findings of this study have significant implications for both sports performance and rehabilitation contexts. Understanding how postural stability and core function influence BLD in elbow flexion can inform the design of more effective training and rehabilitation programs. For athletes, training protocols can be tailored to either reduce or exploit BLD depending on the specific demands of their sport, such as optimizing bilateral strength for symmetrical sports or enhancing unilateral strength for sports requiring asymmetrical movements. In rehabilitation, practitioners can use these insights to develop targeted interventions that improve functional strength and stability in patients recovering from upper limb injuries. Additionally, the comparison between functional and analytical assessments provides valuable information for selecting the most appropriate evaluation methods in clinical and sports settings, ensuring that strength assessments are both relevant and transferable to real-world tasks.  
The knowledge obtained from this research allows us to determine BLD in the upper extremities through functional movement. In addition, it makes it possible to determine the influence of position on BLD, thus discriminating which method presents a lower BLD.  
Conceptualization, I.P.-T., I.C.-R., L.C.-R. and D.J.-M.; methodology, I.P.-T., I.C.-R., L.C.-R. and D.J.-M.; software, I.P.-T., I.C.-R., L.C.-R. and D.J.-M.; validation, I.P.-T., I.C.-R., L.C.-R. and D.J.-M.; formal analysis, I.P.-T., I.C.-R., L.C.-R. and D.J.-M.; investigation, I.P.-T., R.E.-M., A.G.-R. and I.d.-C.; resources, I.P.-T., R.E.-M., A.G.-R. and I.d.-C.; data curation, I.P.-T., I.C.-R., L.C.-R. and D.J.-M.; writing--original draft preparation, I.P.-T.; writing--review and editing, I.P.-T., R.E.-M., A.G.-R., I.d.-C., I.C.-R. and D.J.-M.; visualization, I.P.-T., I.C.-R., L.C.-R. and D.J.-M.; supervision, I.C.-R., L.C.-R. and D.J.-M.; project administration, I.P.-T., I.C.-R., L.C.-R. and D.J.-M.; funding acquisition, I.P.-T., I.C.-R., L.C.-R. and D.J.-M. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the FEDER/Junta de Andalucia/Project (B-CTS-184-UGR20) and Consejeria de Universidad, Investigacion e Innovacion (A.SEJ.227.UGR23).  
Institutional Review Board Statement: The study protocol adhered to the tenets of the Declaration of Helsinki and was approved by the University of Granada Institutional Review Board (IRB approval: 928/CEIH/2019). Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. Data Availability Statement: The raw data supporting the conclusions of this article will be made available by the corresponding author on request. This paper will be part of [PERSON] Doctoral Thesis performed in the Biomedicine Program of the University of Granada. The authors declare no conflicts of interest.