Input and Soft-Tissue Vibration Characteristics during Sport-Specific Tasks

Purpose To assess the influence of sport-specific tasks on the characteristics of input and soft-tissue vibrations. Methods Triaxial accelerometers were used to quantify the input (heel cup of the shoe) and soft-tissue vibrations of the gastrocnemius medialis and vastus lateralis muscles during seven sport-specific tasks performed by 10 healthy volunteers. A wavelet analysis was used to analyze the acceleration signals in the time-frequency domain. The energy and frequency of the input and soft-tissue vibrations, as well as the transmission of energy from the input to the muscles and the damping properties of soft tissues, were computed. Results Different inputs, energy transmissions, and damping properties were found between the various movements. Landings and side cuts induced the greatest input frequency and energy, as well as the greatest soft-tissue vibration energy. These tasks produced up to three times greater energy than in-line running. Positive energy transmission was found for frequencies under 50 Hz and for frequencies up to 90 Hz for some movements, indicating a possible change in the natural frequency of vibration within muscle. Only small differences in damping properties were found, which may indicate that the attenuation of the vibration was not the priority during these tasks. Conclusions Athletes are subject to greater energy impacts and vibrations during some sport-specific tasks compared with running. It may be useful to decrease such input/vibration energy via the usage of footwear or compression tools to limit their potential deleterious effects on the musculoskeletal system. It is, therefore, recommended to quantify and control the number of impacts induced by the different sport-specific tasks.