【論文摘要】Effect of Bilateral Symmetry on Postural Stability During Single-Leg Stance in Poomsae Athletes

【論文摘要】跆拳道品勢運動員雙側對稱性對獨立步姿勢穩定度的影響

張耀宗(Yao-Zong Chang) ； 賴建宏(Chien-Hung Lai) ； 劉宏楷(Hong-Kai Liu) ； 潘姿玲(Tzu-Ling Pan) ； 楊文傑(Wen-Chieh Yang)

《物理治療》 47卷2期 (2022/06) Pp. 137-138

https://doi.org/10.6215/FJPT.202206.P19

摘要

Background and Purpose: Poomsae is a set of defined defense-and-attack poses to show Taekwondo skills. Kumgang is the most difficult set due to multiple stability-demanding ＂crane-stance＂ (single-leg stance) poses. Asymmetry decreases sports performance and increases injury risk. Therefore, we investigated bilateral symmetry and postural stability during single-leg stance in Poomsae athletes. Methods: Thirteen athletes underwent the Y balance test on both sides and were assigned to symmetrical (bilateral difference ≤ 10%) and asymmetrical (bilateral difference ＞ 10%) groups. Participants then performed the Kumgang set. Joint angles of legs and plantar pressure distribution were measured. A crane-stance pose included a dynamic phase featuring the transition from double-leg stance to single-leg stance while spinning 90 degrees on the supporting leg, and a static phase featuring the maintenance of single-leg stance. Postural stability was evaluated using center-of-pressure (COP) travel distance (dynamic phase) and sway area (static phase). Mann-Whitney U test was used to compare the symmetrical and asymmetrical groups. Results: Two groups showed no difference in baseline, though the symmetrical group had a longer Y reaching distance (normalized by leg length) on the weaker side (having shorter reaching distance) than the asymmetrical group (symmetrical: 92.8 ± 6.2%, asymmetrical: 86.2 ± 10.1%, p = 0.01). In the dynamic phase, symmetrical group had a shorter but non-significant COP travel distance than asymmetrical group (symmetrical: 7.4 ± 4.2 cm, asymmetrical: 8.8 ± 5.1 cm, p = 0.06). In the static phase, symmetrical group had a lower COP sway area than asymmetrical group (symmetrical: 8.2 ± 5.5 cm^2, asymmetrical: 11.3 ± 6.1 cm^2, p = 0.04). In addition, symmetrical group showed higher knee flexion in both dominant (symmetrical: 64.2 ± 7.1°, asymmetrical: 56.4 ± 8.1°, p = 0.04) and non-dominant (symmetrical: 62.1 ± 7.6°, asymmetrical: 54.4 ± 9.2°, p = 0.03) sides during the static phase than asymmetrical group. Conclusions: Athletes with higher symmetry showed greater leg functional strength, which may help achieve better postural stability by lowering body mass with knee flexion. Clinical Relevance: Leg functional strength is critical for stability during the crane-stance pose, thus should be emphasized in training program.