# Precision and Reliability of a Dynamometer for Trunk Extension Strength and Steadiness Assessment
## 4 Discussion
Nonetheless, factors such as neuromuscular noise, simultaneous execution of motor tasks, and variations in concentration could affect trunk force steadiness, emphasizing the importance of comprehensive evaluations of the system's reliability [7; 39; 48; 49]. In the literature, various protocols have been identified for evaluating the isometric strength of the trunk. For instance, utilized a protocol using a handheld dynamometer to measure maximal lumbar extensor strength at trunk flexion of 30\({}^{\circ}\) and prone extension at 0\({}^{\circ}\)[34]. This is similar to our choice of a 20\({}^{\circ}\) inclination, as increased gravitational force at 0\({}^{\circ}\) may create a mechanical disadvantage for force production [49; 50]. Our findings align with previous research validating the use of dynamometers to assess trunk extensors. Unlike standing positions, which may introduce support-related variations, the 20\({}^{\circ}\) inclination accounts for biomechanical factors, for example, the stabilization of the pelvis, a reduction in compensations, and postural stability, and external variables [34]. Controlled inclinations during isometric strength evaluations have been shown to reduce gravitational effects and muscular discomfort, thereby improving measurement accuracy [36; 51]. Standardization is particularly crucial for patients with chronic LBP, enabling safer and more precise spinal extensor assessments [14]. Adopting a reliable position such as the 20\({}^{\circ}\) inclination ensures reliable and clinically relevant outcomes, even for healthy individuals and with mobility restrictions [17; 34]. The assessment of force steadiness is fundamental to understanding motor performance, especially in the muscles involved in postural control and affecting movement efficiency [39; 52; 53; 54]. Clinically, trunk strength and force steadiness deficits impair quality of life. In individuals with LBP, muscle instability often contributes to persistent pain and functional limitations [2; 7; 27; 55]. Dynamometer-based systems provide a precise evaluation of muscle force steadiness, identifying motor control deficits and supporting the development of more effective rehabilitation strategies. Additionally, the device's ability to provide real-time force curve feedback can enhance neuromuscular re-education, minimizing compensatory patterns that exacerbate injuries or lead to new ones [22; 29; 56]. The reliability demonstrated by the developed device for trunk force steadiness assessment has significant implications for tracking functional progress and tailoring therapeutic inter ventions. It offers healthcare professionals, including physical therapists, physicians, and sports educators, a practical and reliable tool to optimize clinical decision-making. This study acknowledges certain limitations, including the absence of a gold-standard device for validating variables such as steadiness across different testing protocols and postures. Although standardized instructions and consistent verbal encouragement were provided to minimize external influences, psychological factors like anxiety and stress may have impacted participants' performance [57, 58]. Additionally, variations in physical activity levels were not strictly controlled. Future research should focus on longitudinal studies to assess the dynamometer's effectiveness in tracking therapeutic progress and explore its application in diverse populations, including older adults, athletes, and individuals with specific musculoskeletal conditions, while validating its performance against reference methods. Additionally, studies could investigate the feasibility of using more portable and user-friendly versions of the dynamometer in clinical and field settings, ensuring that it can be easily incorporated into routine practice without compromising data accuracy. Exploring the impact of various environmental and participant factors on the device's performance would also be critical to enhance its applicability in different real-world contexts.