## 1 Introduction  
The rings are one of the six apparatuses featured in the men's Olympic artistic gymnastics program. A significant portion of the skills performed on the rings consists of slow-moving or static hold elements, such as the swallow, the iron cross and the support scale, which require a long training process to be achieved [1]. These elements deeply influence the athletes' final competitive score on the rings [2]. In order to strengthen the muscle groups involved in these elements, athletes typically incorporate into their training routines a series of exercises defined as Preconditioning Strengthening Exercises (PSEs), performed through the use of pulley systems, dumbbells, barbells or loop bands [3]. Athletes typically perform these exercises with a load corresponding to at least 75% of their body weight, as this is considered the minimum threshold required to sustain holding elements on the rings [3]. [PERSON] and colleagues [4] reported that the use of a counterweight system (with a load of 18 \(\pm\) 9% of the athlete's body weight) could replicate the technique of the swallow, but with a lower muscle excitation of the pectoralis major compared to the main element. Additionally, special supports that reduce the arm lever have been used to reproduce the iron cross with a lower muscle strain, a reduced shoulder asymmetry and a reduction in unnecessary and incorrect movements and positions [5,6]. Similarly, [PERSON] et al. (2025), studying the muscle excitation and synergies of the support scale and its PSEs, reported that the use of pulley systems helped athletes to replicate the correct technique, emphasizing the position of the scapulae, while lifting two dumbbells in a standing position may be useful to strengthen the action of the shoulder flexor muscles that are typically involved on the competition rings [7]. Thus, analyzing muscle excitation and synergies during holding elements in gymnastics could help coaches and researchers to identify the specific characteristic of the technical elements and to determine which exercises should be included in training sessions based on the primary aim of the workout.  
The Inverted Swallow (IS) represents a more advanced upper-body skill in artistic gymnastics and calisthenics compared to the aforementioned hold elements. This exercise, indeed, is rarely performed alone or in combination with swing elements during rings competitions [8]. The IS consists of a horizontal supine body position with the arms fully extended at rings height (Figure 1). The limited execution of this element makes it difficult to fully understand its specific muscular demands and to identify the most effective exercises to replicate muscle excitations and synergies. Athletes typically use different PSEs in their attempts to learn or improve the IS; however, to the best of our knowledge, the excitation of the main muscle groups during the IS and the effectiveness of the PSEs used in training routines have not been investigated. Therefore, this study aimed to analyze and compare the muscle excitations and synergies during the Inverted Swallow and during five different PSEs commonly used in training by athletes. The authors hypothesized different muscle excitation between IS and its PSEs and that employing a counterweight pulley system may enable athletes to more accurately reproduce the technical position and muscle synergies of the main competitive exercise, as compared to the other PSEs.