# Beyond Simple Tapping: Is Timed Body Movement Influenced When Balance Is Threatened?
## 1 Introduction
However, there appears to be a lack of data concerning the timing aspects of complex and large-scale multi-segmental (e.g., squatting) or single-segment (e.g., lower or upper extremity abduction/adduction, flexion/extension) body movements as those typically employed in physical fitness or rehabilitative modalities. These more complex large-scale or single-segment movements differ from finger tapping in several key ways. They require greater muscular force and involve a wider range of motion. However, the most important difference most likely lies in the sensory information providing the movement's endpoints, which is considered to play a significant role in movement timing and temporal accuracy [2]. In finger tapping, surface contact provides clear spatial cues that help determine the precise moment of action. In contrast, the multi-segmental or single-segment movements used in fitness and rehabilitation rely more on proprioceptive cues, as there are no explicit contact points. As a result, these movements depend less on explicit temporal representation and more on implicit timing, where regularities are derived from movement variables rather than direct time cues [13]. A key factor that may influence the timing of these large-scale movements is the threat to balance. For example, exercises like standing hip abduction, performed on one leg, present a greater balance challenge compared to two-legged squatting, which benefits from a wider base of support. Understanding how the balance threat affects timing is essential, especially for movements constrained to align with auditory cues. Previous research highlights a connection between balance and timing [16]. In particular, [PERSON] and coworkers [16] found that higher balance demands, such as standing, resulted in slower compensation for metronome timing shifts (increased synchronization error), though the overall variability remained unaffected. Similarly, [PERSON] and [PERSON] [17] also observed fewer taps during single-leg standing compared to seated tapping, further suggesting that balance threats can impact timing performance. Considering the limitations of the tapping paradigm (finger or foot tapping), research should extend to more complex and large-scale multi-segmental or single-segment timed movements, without explicit external spatial sensory feedback. Such an approach would provide a more ecologically valid context for studying sensorimotor synchronization at movement conditions where the participants themselves set the spatial boundaries, such as the depth of a squat or the range of motion in standing hip abduction. The aim of this study was to investigate the timing of movement beyond the tapping paradigm, employing two large-scale movements commonly performed in physical fitness or rehabilitation modalities, performed without contact surface endpoints, as occurs in the tapping paradigm and with varying inherent balance threats: the two-legged squatting (low balance threat) and the standing hip abduction (higher balance threat). We hypothesized that movement timing would differ between the two-legged squatting and the standing hip abduction due to the inherent balance threat in the latter. In particular, we expected similar entrainment measures but different temporal accuracy reflected at reduced pace stability and increased timing errors (entrainment error and synchronization one).