# Beyond Simple Tapping: Is Timed Body Movement Influenced When Balance Is Threatened?
## 4 Discussion
This finding is consistent with previous research demonstrating that tasks with greater balance challenges tend to introduce more timing variability [2; 16]. It also supports the idea that pace stability is influenced by the complexity of the movement, with more complex or more challenging movements exhibiting greater timing variability due to the increased demands on balancing motor control [15]. Due to its inherent balance threat, the standing hip abduction most likely also involves greater proprioceptive demands. In the absence of external spatial feedback, timing variability may be exacerbated due to increased reliance on internal sensory information [2]. Thus, in standing hip abduction, a balance threat interference may interfere by leading to a greater reliance on proprioceptive and cognitive information to achieve a successfully timed movement, while at the same time mitigating the balance loss to ensure the safety of performance [40]. The direction of the IRI error, as well as the direction of the synchronization error, did not differ between the two exercises, suggesting that the balance threat did not bias the direction of the timing errors. Participants showed a consistent prevalence of both overestimation and underestimation of movement intervals, as well as of earlier and later movement onsets, regardless of the greater balance threat in the standing hip abduction. This indicates that while balance challenges impact overall timing accuracy, they do not necessarily alter the internal process of timing adjustments [41]. According to the Adaptation and Anticipation Model (ADAM) of sensorimotor synchronization, error correction mechanisms are essential for maintaining temporal alignment and coping with timing variability [41]. The model highlights how phase and period correction processes (operating both reactively and predictively) help adapt to timing changes without systematically altering the direction of errors [42; 43]. The observed consistency of these measures under varying balance conditions underscores the resilience of the sensorimotor synchronization mechanisms, as well as their flexible adaptation to varying demands [43]. It appears that, despite balance challenges impacting the timing accuracy, the underlying error correction mechanisms remain robust and maintain their efficacy across different contexts [41; 42]. This study provides timed-movement insights beyond the traditional finger-tapping paradigm by examining larger-scale, multi-segmental (two-legged squatting) and single-segmental (standing hip abduction) movements, with the latter introducing a higher balance threat. The justification of our study rationale is reflected in the increased magnitude of the variables expressing the aspects of movement timing compared to those in typical finger-tapping studies. For the movements examined in our study, entrainment was succeeded with an IRI error at 3.5% for two-legged squatting and at 5.3% for standing hip abduction, indicating an increase of 3.5- to 5.3-times compared to the 1% IRI error typically reported in finger-tapping studies [5; 6]. Synchronization was also succeeded with a greater synchronization error that averaged 16.8% in two-legged squatting, indicating an increase of 1.5- to 2-times greater than the 8-11% observed in finger tapping [5; 6]. In standing hip abduction, the synchronization error averaged 11.9%, which was also higher than the values reported for finger tapping but rather closer to the upper limit of the 8-11% finger-tapping range [5; 6]. Motor timing is influenced not only by task complexity but also by the speed constraints inherent to the task. Motor control as well as behavioral studies indicate that movement timing is constrained by both the motor system's capacity to move rapidly [5; 6] and the cognitive system's ability to maintain precise control [13; 44], with predictive timing becoming increasingly difficult as the tempo either speeds up or slows down.