Purpose. The purpose of this study is to compare the time-frequency characteristic, using non-linearly scaled wavelets, the amplitude and the timing of the electromyography (EMG) signal, as well as the three-dimensional (3D) kinematics of the lower limb of female and male elite soccer players performing an unanticipated cutting manoeuvre. Methods. Fifteen female and 15 male elite soccer players performed a series of the cutting manoeuvre during which EMG of eight muscles of the right leg, 3D kinematics of the hip, knee and ankle, as well as ground reaction forces were recorded. To create an unanticipated condition, the participants executed one of three tasks, which were signalled to them with an illuminated target board. All variables were compared between genders by means of one-way ANOVAs. Results. Female participants performed the cutting task with greater knee valgus and ankle pronation angles, as well as smaller hip internal rotation and ankle external rotation angles, than did the male group. Women also displayed different muscle activation patterns, such as an earlier semitendinosus (ST) onset, greater peak rectus femoris (RF) activity, greater lateral gastrocnemius (LG) and tibialis anterior (TA) activity at initial contact (IC) and greater LG activity during the entire motion. Furthermore, men executed the cutting manoeuvre with higher frequency components for the quadriceps and higher frequencies at IC for the biceps femoris (BF). These higher frequencies dominated the signal earlier in time for the BF and later for the TA in women. Conclusion. Gender differences in lower limb kinematics were observed, possibly exposing the female anterior cruciate ligament (ACL) to higher strain. Women also exhibited neuromuscular control strategies that may assist in explaining the gender bias in ACL injury rates. The frequency at which one contracts a muscle to sustain joint stability may be of greater importance than the amount of muscle activity. Key Words. Anterior cruciate ligament, Knee Injury, Gender, Wavelet, Neuromuscular Control, Kinematics.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/27330 |
| Date | January 2006 |
| Creators | Beaulieu, Melanie |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 102 p. |
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