|M.Sc Thesis||Department of Biomedical Engineering|
|Supervisor:||Prof. Mizrahi Joseph|
In the present thesis we investigate the EMG signal assessments as well as the relationship between the Electromyogram (EMG) and kinematics signals, in order to obtain more information regarding muscular fatigue, during level and downhill running.
The purpose of this research was to analyze the following:
1. Existence of correlation between the Quadriceps integrated EMG and the knee angular velocity difference during level and downhill running.
2. Estimation of muscular activity of each of the Gastrocnemius and Tibialis Anterior through the relationship with the ankle kinematics.
3. Examination of muscular fatigue of the Tibialis Anterior in the eccentric phase of the stance and in the swing phase during level running, as well as of the Quadriceps in the stance phase during downhill running.
4. Verify whether the period of muscular activity of each of the Gastrocnemius (stride cycle), Quadriceps and Tibialis Anterior increases with progressing fatigue.
The experiment consisted of running of fourteen young male subjects on a treadmill for 30 minutes in two running protocols (Level running and Downhill running). The EMG data of the Gastrocnemius, Tibialis Anterior and Quadriceps muscles were acquired every 5 minutes within a time span of 20 sec at a sampling rate of 1667 Hz. The kinematics signals coming from video acquisition were collected every 15 minutes within a time span of 12 sec. The angular displacement signal of the knee and ankle were acquired from the video data at a sample frequency of 50 Hz. Co-contraction between antogist muscles was predicted by means of a defined weight factor.
The following results were obtained:
A significant increase was observed of the Quadriceps muscular activity during downhill running in relation to the knee angular velocity difference. However, this correlation was not linear. A significant increase of the Gastrocnemius muscular activity and a significant decrease of the Tibialis Anterior muscular activity during the stance phase were observed during level and downhill running. There was a high muscular activity of the Tibialis Anterior and a low muscular activity of the Gastrocnemius in the swing section. With progresing fatigue, the Tibialis Anterior manifested a significant decrease in activity in the swing phase during level running. Additionally, the Quadriceps integrated EMG signal presented a significant increase in the concentric segment of the stance phase and in the swing phase, during download running. Stride time results indicated a decrease in the period of muscular activity of the Tibialis Anterior.
In conclusion, the obtained relationship between the muscular activity and the changes in angular velocity of the joint provides quantitative information about the EMG, in relation to kinematics, as fatigue progreses.