Functional Fatigue Alters Lower-extremity Neuromechanics during a Forward-side Jump

Abstract

Neuromuscular fatigue impairs neuromuscular control of the lower extremity. The purpose of the study was to investigate the effect of functional fatiguing exercises on sagittal-plane lower-extremity neuromechanics during a forward-side jump. 21 participants performed 5 forward-side jump tasks before and after functional fatiguing exercises. A functional analysis of variance (FANOVA) evaluated differences between 2 different conditions (pre- vs. post-fatigue) for joint angle, moment, and EMG amplitude during stance of a forward-side jump. FANOVA compared variables as polynomial functions, and differences between functions with 95% confidence interval bands were plotted to determine significant differences. Plantar, knee, and hip flexion decreased during the initial stages of landing following fatigue. Plantarflexion moment decreased during 10-20% of stance in post-fatigue. Knee extension moment initially increased while decreased during 20-30% of stance following fatigue. Hip extension moment initially decreased while increased at 20% of stance. Tibialis anterior EMG decreased during 30-40% of stance, vastus lateralis EMG increased at 15% of stance, hamstring EMG decreased at foot contact and during 25-60% of stance, and gluteus maximus EMG decreased at foot contact and 35% of stance. The functional fatiguing exercises resulted in a more upright landing position, potentially indicating a greater reliance upon skeletal structures for support.

Altered Walking Neuromechanics in Patients With Chronic Ankle Instability

“…Details of the data processing have been described. 30,32 The spatial trajectories of the reflective markers were tracked using Vicon software and exported into Visual 3D (C-Motion, Germantown, MD), and 3D kinematics and kinetics were calculated. Marker trajectories and force-plate data were smoothed using a fourth-order, low-pass Butterworth filter with a cutoff frequency of 6 Hz.…”

“…33 Reference muscle-activation data were obtained using a goniometer (model EGM-422; Elite Medical Instruments, Inc, Fullerton, CA) during a 3-second isometric double-legged squat position (458 of knee flexion and 308 of hip flexion) before the walking trials. 32,34 Muscleactivation data were smoothed using a root mean square algorithm with a moving window of 125 milliseconds and normalized to the smoothed reference muscle-activation data using custom-written algorithms in MATLAB (The Math-Works, Inc, Natick, MA). 32,34 The stance phase of walking was defined as the time when the involved foot was in contact with the force plate.…”

“…32,34 Muscleactivation data were smoothed using a root mean square algorithm with a moving window of 125 milliseconds and normalized to the smoothed reference muscle-activation data using custom-written algorithms in MATLAB (The Math-Works, Inc, Natick, MA). 32,34 The stance phase of walking was defined as the time when the involved foot was in contact with the force plate. A vertical GRF of 15 N was used as the threshold to determine heel strike and toe-off of the involved limb during walking.…”

Effects of Anaerobic Fatigue on the Tuck Jump Assessment Performance in Female Collegiate Club Athletes

“…4,5,[7][8][9] Several studies have shown that fatigue can cause a decrease in neuromuscular control and biomechanics during jumping and landing tasks. 3,[10][11][12] Fatigue can be defined as a decline in muscular ability to maintain necessary mechanical work for a given function. 13 Fatigue has also been shown to have many effects on athletic performance, including a decrease in muscle control and strength 13 , decrease in ability to generate power 14 impaired strength, biomechanics, and central activation 12 .…”

“…biomechanics, therefore decreasing their abilities to perform a functional test when comparing groups under pre-fatiguing and post-fatiguing conditions. [10][11][12] Limited research has been performed with the TJA in combination with a fatiguing method prior to this current study. [4][5][6][7] The TJA was created to replicate sport activity, however, if fatigue is not achieved, then the validity of the TJA may be limited.…”