Surface-EMG analysis for the quantification of thigh muscle dynamic co-contractions during normal gait

• Published in: Gait & posture Vol. 51; no. NA; pp. 228 - 233
• Main Authors: Strazza, Annachiara, Mengarelli, Alessandro, Fioretti, Sandro, Burattini, Laura, Agostini, Valentina, Knaflitz, Marco, Di Nardo, Francesco
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.01.2017
• Subjects: Antagonist muscles; Co-contraction; Electromyography; Female; Gait; Hamstring Muscles - physiology; Humans; Knee; Male; Muscle Contraction - physiology; Muscle, Skeletal - physiology; Orthopedics; Quadriceps Muscle - physiology; Reference Values; Reproducibility of Results; sEMG; Statistical gait analysis; Thigh - physiology; Walking; Young Adult; Knee; F; Statistical gait analysis; H; Antagonist muscles; SGA; P; Co-contraction; S; RF; QF; VL; sEMG; MH; GC; quadriceps femoris; gait cycle; vastus lateralis; statistical gait analysis; swing; medial hamstrings; push-off; flat foot contact; rectus femoris; heel contact
• ISSN: 0966-6362; 1879-2219; 1879-2219
• DOI: 10.1016/j.gaitpost.2016.11.003

•Thigh muscle co-contractions were assessed in 30 healthy adults during gait.•Hundreds of consecutive strides were analyzed for each subject.•Three different co-contractions among QF and hamstring muscles were identify.•Onset-offset instants, excitation intensity and occurrence frequency were provided. The research purpose was to quantify the co-contraction patterns of quadriceps femoris (QF) vs. hamstring muscles during free walking, in terms of onset-offset muscular activation, excitation intensity, and occurrence frequency. Statistical gait analysis was performed on surface-EMG signals from vastus lateralis (VL), rectus femoris (RF), and medial hamstrings (MH), in 16315 strides walked by 30 healthy young adults. Results showed full superimpositions of MH with both VL and RF activity from terminal swing, 80 to 100% of gait cycle (GC), to the successive loading response (≈0–15% of GC), in around 90% of the considered strides. A further superimposition was detected during the push-off phase both between VL and MH activation intervals (38.6±12.8% to 44.1±9.6% of GC) in 21.9±13.6% of strides, and between RF and MH activation intervals (45.9±5.3% to 50.7±9.7 of GC) in 32.7±15.1% of strides. These findings led to identify three different co-contractions among QF and hamstring muscles during able-bodied walking: in early stance (in ≈90% of strides), in push-off (in 25–30% of strides) and in terminal swing (in ≈90% of strides). The co-contraction in terminal swing is the one with the highest levels of muscle excitation intensity. To our knowledge, this analysis represents the first attempt for quantification of QF/hamstring muscles co-contraction in young healthy subjects during normal gait, able to include the physiological variability of the phenomenon.