Study of muscle vibrations in sports practice and their effects on the body

This thesis aims to characterize soft tissue vibrations (i.e., their amplitude, frequency, damping) during different sports practices, such as running, tennis or team sports, and to evaluate the link between vibrations and the appearance of muscle fatigue.

Soft tissues are composed of the muscle, which is the tissue of interest, but also of more superficial tissues such as fat and skin. Since the vibrations are measured using accelerometers attached to the skin, we evaluated the influence of the superficial tissues on the measured vibration by comparing it to the muscle vibration measured by ultra-fast ultrasound. This study depicted that the greater the skin fold under the accelerometer, the less the vibrations measured on the skin reflected the muscle vibrations.

In addition, we evaluated how the conditions of sports practice, such as running speed or the movement performed, modified the vibrations. The increase in running speed resulted in greater impacts and vibrations at higher frequencies, but these vibrations remained at lower amplitudes than those experienced in team sports, such as receptions or side-cuts.

The objective is to determine what characteristics of vibration may be related to the onset of fatigue and muscle damages. These results could allow to improve the monitoring of the athlete's load, by adding the monitoring of a dose of vibration, but also to guide the manufacturers of the sports world in the development of equipment and damping solutions.