School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China.
Department of Kinesiology and Health, University of Wyoming, Laramie 82070, WY, USA.
J Sports Sci Med. 2018 Nov 20;17(4):640-649. eCollection 2018 Dec.
The aim of this study was to determine the effects of two fatigue protocols on lower-limb joint mechanics, stiffness and energy absorption during drop landings. Fifteen male athletes completed landing tasks before and after two fatigue protocols (constant speed running [R-FP] and repeated shuttle sprint plus vertical jump [SJ-FP]). Sagittal plane lower-limb kinematics and ground reaction forces were recorded. Compared with R-FP, SJ-FP required significantly less intervention time to produce a fatigue state. The ranges of motion (RoM) of the hip were significantly greater when the athletes were fatigued for both protocols. Knee RoM significantly increased after SJ-FP but not after R-FP (p > 0.05), whereas the RoM of the ankle was significantly greater after R-FP but lower after SJ-FP. When fatigued, the first peak knee extension moment was significantly greater in R-FP but lower in SJ-FP; the second peak ankle plantar flexion moment was lower, regardless of protocols. After fatigue, vertical, hip, and knee stiffness was lower, and more energy was absorbed at the hip and knee for both protocols. Hip and knee extensors played a crucial role in altering movement control strategies to maintain similar impact forces and to dissipate more energy through a flexed landing posture when fatigued compared to when non-fatigued. Furthermore, SJ-FP seems to be a more efficient method to induce fatigue due to less intervention time than R-FP.
本研究旨在确定两种疲劳方案对落地时下肢关节力学、刚度和能量吸收的影响。15 名男性运动员在两种疲劳方案（恒速跑步[R-FP]和重复穿梭短跑加垂直跳跃[SJ-FP]）前后完成了着陆任务。记录矢状面下肢运动学和地面反作用力。与 R-FP 相比，SJ-FP 完成疲劳状态所需的干预时间明显更少。两种方案下，运动员疲劳时髋关节的运动范围（RoM）明显更大。SJ-FP 后膝关节 RoM 显著增加，但 R-FP 后则无显著变化（p>0.05），而踝关节 RoM 在 R-FP 后显著增加，SJ-FP 后则显著降低。疲劳时，R-FP 中第一峰值膝关节伸展力矩显著增加，SJ-FP 中则显著降低；第二峰值踝关节跖屈力矩降低，与方案无关。疲劳后，垂直、髋关节和膝关节的刚度降低，两种方案下髋关节和膝关节吸收的能量更多。髋关节和膝关节伸肌在改变运动控制策略方面发挥着至关重要的作用，以在疲劳时保持相似的冲击力，并通过弯曲的着陆姿势来消耗更多的能量。此外，与 R-FP 相比，SJ-FP 由于干预时间更短，似乎是一种更有效的疲劳诱导方法。
