title: 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.
authors.affiliation: Exercise Sciences, Brigham Young University, Provo, United States.
authors.forename: H
authors.initials: H
authors.lastname: Kim
authors.affiliation: Exercise Sciences, Brigham Young University, Provo, United States.
authors.forename: S
authors.initials: S
authors.lastname: Son
authors.affiliation: Exercise Sciences, Brigham Young University, Provo, United States.
authors.forename: M K
authors.initials: MK
authors.lastname: Seeley
authors.affiliation: Human Performance Research Center, Brigham Young University, Provo, United States.
authors.forename: J T
authors.initials: JT
authors.lastname: Hopkins
mesh_terms: D000704:Analysis of Variance; D000842:Ankle / Q000502:physiology; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006615:Hip / Q000502:physiology; D006801:Humans; D007717:Knee / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation; D059385:Plyometric Exercise; D055815:Young Adult