Int J Sports Med 2015; 36(14): 1192-1200
DOI: 10.1055/s-0035-1550050
Orthopedics & Biomechanics
© Georg Thieme Verlag KG Stuttgart · New York

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

H. Kim
1   Exercise Sciences, Brigham Young University, Provo, United States
,
S. Son
1   Exercise Sciences, Brigham Young University, Provo, United States
,
M. K. Seeley
1   Exercise Sciences, Brigham Young University, Provo, United States
,
J. T. Hopkins
2   Human Performance Research Center, Brigham Young University, Provo, United States
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Publikationsverlauf



accepted after revision 28. April 2015

Publikationsdatum:
30. September 2015 (online)

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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.