Abstract：
This study examines the effects of limb dominance and lead limb in task initiation on the kinetics and kinematics of step-off drop landings. Nineteen male participants performed drop landings led by the dominant and non-dominant limbs at 45-cm and 60-cm drop heights. Ground reaction force (GRF) and lower body kinematic data were collected. Between-limb time differences at the initial ground contact were calculated to indicate temporal asymmetry. Statistical Parametric Mapping (SPM) was applied for waveform analysis while two-way repeated measures ANOVA was used for discrete parameters. SPM results revealed greater GRF and lesser ankle dorsiflexion in the lead limb compared to the trail limb in 3 out of 4 landing conditions. The dominant limb displayed a greater forefoot loading rate (45 cm: p=.009, ηp2 = 0.438; 60 cm: p=.035, ηp2 = 0.225) and greater ankle joint quasi-stiffness (45 cm: p < .001, ηp2 = 0.360; 60 cm: p < .001, ηp2 = 0.597) than the non-dominant limb. Not all 380 trials were lead-limb first landings, with a smaller between-limb time difference (p=.009, d = 0.60) at 60 cm (4.1 ± 2.3 ms) than 45 cm (5.6 ± 2.7 ms). In conclusion, the step-off drop landing is not an ideal protocol for examining bilateral asymmetry in lower limb biomechanics due to potential biases introduced by limb dominance and the step-off limb.
摘要：
这项研究考察了任务启动中肢体优势和引导肢体对步降着陆动力学和运动学的影响。19名男性参与者在45厘米和60厘米的跌落高度上进行了由优势和非优势肢体引导的跌落着陆。收集地面反作用力（GRF）和下半身运动学数据。计算初始地面接触时的肢体间时间差以指示时间不对称性。统计参数映射(SPM)用于波形分析,而双向重复测量ANOVA用于离散参数。SPM结果显示，在4种着陆条件中的3种情况下，与前肢相比，前肢的GRF更大，踝关节背屈更小。优势肢显示出较高的前足负荷率（45cm：p=.009，ηp2=0.438；60cm：p=.035，ηp2=0.225）和较高的踝关节准刚度（45cm：p<.001，ηp2=0.360；60cm：p<.001，ηp2=0.597）。并非所有380项试验都是铅肢体首次着陆，在60cm（4.1±2.3ms）处的肢体间时间差（p=.009，d=0.60）小于45cm（5.6±2.7ms）。总之,由于肢体优势和跨步肢体带来的潜在偏差,跨步着陆不是检查下肢生物力学双侧不对称性的理想方案.
