Effects of Two Fatigue Protocols on Impact Forces and Lower Extremity Kinematics during Drop Landings: Implications for Noncontact Anterior Cruciate Ligament Injury.

Rui Xia,Xini Zhang,Weijie Fu,Xi Wang,Xiaole Sun

doi:10.1155/2017/5690519

Abstract

The purpose of the study was to determine the effects of fatigue on the impact forces and sagittal plane kinematics of the lower extremities in a drop landing task. 15 male collegiate athletes were recruited. Five successful trials of a drop landing task were obtained during prefatigue and postfatigue in two fatigue protocols (constant speed running fatigue protocol [R-FP] and shuttle running + vertical jumping fatigue protocol [SV-FP]). Duration time, maximal heart rate, and RPE of each protocol were measured separately. Kinematic measures of the hip, knee, and ankle joints at different times coupled with peak impact force and loading rate were acquired. Our results showed a more flexed landing posture due to an increase in hip and knee flexion angles in the postfatigue condition. However, no differences in peak impact force and loading rate were found between pre- and postfatigue conditions. The changes were similar between protocols, but the SV-FP showed a significantly shorter exercise duration time than the R-FP. Fatigued athletes in this study demonstrated altered motor control strategies during a drop landing task, which may be an intentional or unintentional protective strategy for preventing themselves from potential ACL injury.

Highlights

Exercise is vital for maintaining health and wellness [1,2,3]
We evaluated the effects of two fatigue protocols (R-FP and Shuttle Running + Vertical Jumping Fatigue Protocol (SV-FP)) on the biomechanics of the lower extremities
No differences were found between the Running Fatigue Protocol (R-FP) and SV-FP for the effect of fatigue on these biomechanical characteristics during landing, we found that the time duration of the SV-FP was significantly less than that of the R-FP, and the maximal heart rate (HR)/min and RPE for these two protocols were similar

Summary

Introduction

Exercise is vital for maintaining health and wellness [1,2,3]. physical activity may cause sport-related injuries, which may be responsible for reduced athletic performance and even lead to sport cessation for long periods [4]. The human body needs to reduce the possible adverse effects of impact during landing, which can reach up to 10 times the body weight, by adjusting landing posture [7]. One can adjust his/her landing posture to reduce the impact force upon ground contact [8]. With prolonged exercise, the human body will produce a temporary reduction in the ability of exercise called sport fatigue, which is an extrinsic factor affecting the neuromusculoskeletal system [10]. These changes are believed to increase the incidence of sport injuries represented by ACL injury [11]

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