Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
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©Journal of Sports Science and Medicine ( 2018 ) 17 , 640 - 649

Research article
Effects of Exercise-Induced Fatigue on Lower Extremity Joint Mechanics, Stiffness, and Energy Absorption during Landings
Xini Zhang1, Rui Xia1, Boyi Dai2, Xiaole Sun1, Weijie Fu1,3, 
Author Information
1 School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China
2 Department of Kinesiology and Health, University of Wyoming, Laramie 82070, WY, USA
3 Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai 200438, China

Weijie Fu
‚úČ PhD Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, 200438 Shanghai, China
Email: fuweijie315@163.com
Publish Date
Received: 21-03-2018
Accepted: 15-10-2018
Published (online): 20-11-2018
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ABSTRACT

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.

Key words: Landing, exercise-induced fatigue, joint mechanics, stiffness, energy absorption


           Key Points
  • Changes in lower extremity biomechanics during drop landings were found between two fatigue protocols.
  • Hip and knee extensors played a crucial role in altering movement control strategies to maintain similar impact forces and to dissipate more energy when fatigued.
  • The common exercise-induced fatigue protocol (repeated shuttle sprint + vertical jump) required less intervention time to reach a fatigue state than constant speed running protocol.
 
 
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