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Metric semantic description
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This metric evaluates the short-term variability in the alignment between the head and trunk, reflecting the stability of the upper-body axis. In épée fencing, maintaining steady head-to-trunk alignment is crucial for effective postural organization, which underpins balance, visual tracking, distance assessment, and precise weapon execution. Lower variability in this measure indicates stronger coherence in posture, contributing to consistent and controlled fencing actions.

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Phenomenon
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Both ATHLETE and OPPONENT exhibit similarly low variability in head-to-trunk alignment, indicating that each maintains stable axial alignment during movement. This equivalence suggests that both athletes demonstrate consistent visual-motor coordination with minimal compensatory adjustments. Their upper-body postural control supports steady balance and reliable weapon handling, reflecting comparable proficiency in maintaining postural coherence during fencing actions.

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Causes
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The stable head-to-trunk alignment observed in both athletes arises from coordinated trunk organization paired with steady head carriage and effective visual-motor coupling. ATHLETE’s and OPPONENT’s postural stability stems from these biomechanical mechanisms functioning reliably, enabling minimal compensations in their upper-body control. Despite differences in armed hand and height, both athletes achieve similar biomechanical coordination in this domain.

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Effects
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This shared stability in axial alignment supports both athletes in accurately reading distance, maintaining balance, and exerting consistent control over their weapons under competitive pressure. The low variability in their head-to-trunk relationship contributes to precise execution and dependable movement quality, enhancing the continuity and clarity of their fencing actions.