# Beyond Simple Tapping: Is Timed Body Movement Influenced When Balance Is Threatened?
## 4 Discussion
This finding most likely highlights the trade-off between stability and accurate timing under balance challenges, even at the preferred tempo entrainment. It appears that when required to follow an auditory pacing cue, the individuals prioritize performance safety, and the focus on maintaining balance may come at the cost of timing accuracy. This observation is consistent with [PERSON] and coworkers [15], who report smaller temporal corrections in their more complex motor task of stepping in place than the simpler finger tapping, suggesting that the central nervous system may prioritize stability over timing accuracy. [PERSON] and coworkers [16] also found that their more complex motor task of stepping in place exhibited slower compensation for timing shifts than their simpler task of heel tapping. Similarly, [PERSON] and [PERSON] [17] reported fewer taps and reduced performance during single-leg standing compared to seated finger tapping. While [PERSON] and [PERSON] [17] did not specifically measure accuracy, their findings suggest that balance challenges, such as single-leg standing, negatively affect performance, supporting the idea that under conditions of greater balance threat, motor tasks become more challenging, which could potentially lead to reduced accuracy in timed movements. Synchronization, unlike entrainment, requires the accurate alignment of self-initiated movements with specific points in an external pacing source. This process involves sophisticated sensorimotor adjustments and error correction mechanisms [8]. Synchronization accuracy is measured by the synchronization error metric, which quantifies the temporal discrepancy between the stimulus pacing event (e.g., auditory beat onset) and the movement event (e.g., movement onset) [4, 6, 8, 10]. Unexpectedly, our findings revealed lower synchronization accuracy (higher synchronization error) during the movement of the reduced balance threat (two-legged squatting) than the one with an inherently greater balance threat (standing hip abduction). This finding contradicts previous results on finger/foot tapping versus stepping in place, where the task of higher balance demands led to worse synchronization accuracy [16]. In our study, the worse synchronization accuracy in the movement under a lower balance threat most likely suggests that factors beyond balance, such as movement complexity and scale, may play a crucial role in accurate timing alignment with external cues [2, 8, 13]. In an effort to maintain synchronization, the increased complexity of two-legged squatting may introduce greater functional variability [37], expressing the \"fine motor tuning\" to correct minor temporal deviations between the movement and the beat onset. This aligns with [PERSON] and coworkers [15], who reported that complex movements lead to less accurate phase adjustments than simpler tasks. The automatic and largely unconscious phase correction process may have been more challenging during two-legged squatting due to larger muscle groups and multiple joint engagements [2, 8, 15, 38]. Thus, despite the inherently lower balance threat, the necessity of timed multi-segmental coordination may produce functional variability that leads to an execution variability that ultimately allows for more accurate synchronization. In timed movements, pace stability is a metric of execution timing variability [39] that evaluates the consistency of movement timing without explicit reference to a cue, and it is quantified by the IRI coefficient of variance [11; 12]. Overall, in both exercises, IRI %CoV was below 10% and rather closer to \(\leq\)5%, indicating the participants' capacity to time their movement with motor stability [23; 24]. However, the standing hip abduction exhibited a significantly higher IRI %CoV than the two-legged squatting, highlighting a notable difficulty to maintain a consistent pace when balance is inherently threatened due to single-leg standing.