## 1 Introduction  
Foot position is a key factor influencing postural stability, significantly impacting balance [1, 2]. Postural stability is defined as the capacity of the Postural Control System to preserve balance and stabilize the orientation and position of body segments in space against gravity while providing continuous neuromuscular adaptations in response to sensory input from the internal body and the external environment [3; 4]. The Postural Control System functions thanks to the integration of the complex network. This network facilitates the convergence of afferent information from peripheral receptors, including visual, stomatognathic, vestibular, and somatosensory inputs, onto the Central Nervous System (CNS) [5; 6]. This dynamic neuromodulation between sensory inputs and motor outputs guarantees the maintenance of the center of pressure (CoP) within the foot support surface during both bipedal standing [7] and dynamic motor tasks, ensuring balance in even the most unstable conditions [8]. All information collected by the receptors located in muscles, tendons, and joints, called proprioceptors, provides feedback to the brain about the body's position and movement [9]. Proprioception is known as the ability to perceive the position of joints and is a crucial factor for joint stability, balance, control, and coordination [10; 11]. In particular, proprioceptive feedback from the feet provides essential information about body sway, especially in conditions of reduced or absent visual input [12; 13]. In fact, previous studies [14; 15; 16] have reported a significant effect of foot position on stabilometric measurements during bipedal stance with closed eyes, whereas no significant variations were found with open eyes. Therefore, choosing the optimal foot placement can significantly aid in the interpretation of clinical and experimental balance control measurements [15]. In addition, a previous study [1] analyzed how the positioning of the feet and the anthropometry of the subject influence stabilometric parameters, while the correlation between anthropometric measurements and self-selected foot placement has yet to be investigated. The impact of foot position on stabilometric parameters has commonly been investigated using pressure and force platforms [1; 17; 18; 19]. During baropodometric exams, forced foot placement has often been used by several authors [17; 18; 19; 20; 21; 22], controlling the inter-heel distance and the between-feet angle. Instead, in other studies, patients are allowed to self-select a comfortable foot position [1; 15; 23; 24]. The variability of stabilometric parameters has been evaluated in the forced foot position compared to a comfortable one [15] or a closed parallel foot position (used in the Romberg test) [16]. The standardized foot position generally used in baropodometric exams takes 30 degrees as the between-feet angle and 3-5 cm as the inter-heel distance [19; 22]. Since these authors reported conflicting points of view regarding the recommended foot position setup for baropodometric exams, there is a need to define the optimal foot placement to reduce variability in postural behavior [1; 15; 21]. As previously stated, visual receptors also play a crucial role in controlling upright posture, both statically and dynamically [5; 7; 25; 26]. In addition, the effect of the visual target distance on postural adaptations, body oscillations, foot contact area, and load distribution has been extensively investigated [27; 28]. In particular, according to a recent study by the same authors [5], a relatively near visual target, placed at approximately 0.7 m from the subject's heels, seems to minimize variability of plantar pressure and stabilometric parameters compared to greater target distances, which can affect body weight distribution and center of pressure oscillations. All the studies mentioned above reported that force and pressure plates are the gold standard instruments for assessing plantar pressure and postural control parameters.