Canadian Sport Institute Calgary, Calgary, Alberta, Canada.
Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
Scand J Med Sci Sports. 2022 Aug;32(8):1192-1200. doi: 10.1111/sms.14168. Epub 2022 May 2.
We quantified the effect of lead leg selection on landing force-time characteristics during a vertical drop landing (VDL) initiated with a step-off. Plyometric-trained subjects (male: n = 8; female: n = 5; age =23 ± 3.3 years; body mass =74.4 ± 11.2 kg) performed 6 step-off-initiated VDLs from a 45-cm box (n = 3/lead leg). Pooled and lead leg stratified between-limb comparisons of limb-specific initial ground contact timing, peak vertical ground reaction force (Fz ), and early landing-phase impulse (Impulse ) were assessed by a two-factor, within-subject ANOVA, and limb symmetry indexes were calculated (α = 0.05). Pooled data showed that the lead leg made contact prior to the trail leg and contributed a greater fraction to Fz compared with the trail leg. Stratifying trials by lead leg selection led to significant between-limb differences in Fz (p < 0.05) and Impulse (p < 0.01) with the right leg leading but not with the left leg leading. Lead leg selection in step-off-initiated VDLs influenced landing performance and limb symmetry indexes of variables associated with lower limb injury risk, suggesting the need to control for lead leg selection in these tasks. A step-off may not be a suitable technique to initiate landing tasks when assessing limb symmetry.
我们量化了在台阶式垂直跳落地（VDL）中选择主导腿对落地力-时间特征的影响。跳躍訓練的受試者（男性：n=8；女性：n=5；年齡=23±3.3 歲；體重=74.4±11.2 公斤）從 45 厘米高的箱子上完成了 6 次台阶式 VDL（每條腿各 3 次）。使用雙因素、被試者內部 ANOVA 評估了肢體特定的初始地面接觸時間、垂直地面反作用力峰值 (Fz) 和早期著地階段衝量 (Impulse) 的雙腿間和單腿間的分層比較，並計算了肢體對稱性指數（α=0.05）。匯總數據表明，主導腿先於跟隨腿接觸地面，並比跟隨腿對 Fz 的貢獻更大。根據主導腿的選擇對試驗進行分層處理，導致 Fz（p<0.05）和 Impulse（p<0.01）在雙腿間存在顯著差異，右腿作主導腿，但左腿作主導腿時則沒有。在階梯式 VDL 中選擇主導腿會影響落地性能和與下肢受傷風險相關的變量的肢體對稱性指數，表明在這些任務中需要控制主導腿的選擇。在評估肢體對稱性時，階梯式可能不是一種合適的起始著地任務的技術。
