Muscles serve as a critical regulator of locomotion and damping, resulting in changes of soft tissue vibration. However, whether muscle fibre compositions of different individuals will cause different extents of soft tissue vibration during gait is unclear. Therefore, this study investigated the differences in lower extremity vibration frequencies among power-trained and non-power-trained athletes during walking and running. Twelve weightlifting athletes were assigned to the power-trained group and twelve recreational runners were assigned to the non-power-trained group. Accelerometers were used to detect soft tissue compartment vibration frequencies of the rectus femoris (RF) and gastrocnemius medialis (GMS) during walking and running. Results indicated that power-trained athletes, as compared to the non-power-trained, induced significantly (p < 0.05) higher vibration frequencies in their soft tissue compartments during walking and running. This suggests that power-trained athletes, who have higher ratios of fatigable fast-twitch muscle fibres, may have induced higher soft tissue compartment vibration frequencies. As a result, there is a likelihood that power-trained athletes may recruit more fatigable fast-twitch muscle fibres during muscle tuning, causing dysfunctions during prolonged exercises.

Whole-body vibration (WBV) is commonly applied in exercise and rehabilitation and its safety issues have been a major concern. Vibration measured using accelerometers can be used to further analyze the vibration transmissibility. Optimal bending angles and rating of perceived exertion (RPE) evaluations have not been sufficiently explored to mitigate the adverse effect. Therefore, the aims of this study were to investigate the effect of various knee flexion angles on the transmissibility to the head and knee, the RPE during WBV exposure, and the link between the transmissibility to the head and the RPE. Sixteen participants randomly performed static squats with knee flexion angles of 90, 110, 130, and 150 degrees on a WBV platform. Three accelerometers were fixed on the head, knee, and center of the vibration platform to provide data of platform-to-head and platform-to-knee transmissibilities. The results showed that the flexion angle of 110 degrees induced the lowest platform-to-head transmissibility and the lowest RPE (p < 0.01). A positive correlation between RPE and the platform-to-head transmissibility was observed. This study concluded that a knee flexion of about 110 degrees is most appropriate for reducing vibration transmissibility. The reported RPE could be used to reflect the vibration impact to the head.

Bat–ball contacts are critical in the baseball hitting process. However, an effective training method for increasing the impact perception of a bat–ball contact is currently unavailable. Although not widely used, hitting a stationary weighted baseball can be an appropriate method for batters to simulate the perception of hitting a moving baseball. Therefore, swing velocity, wrist vibration, and forearm muscle activation for hitting stationary weighted, stationary regulation, and pitched baseballs were investigated in this study. Twelve position players hit a stationary weighted, stationary regulation, and pitched baseball at a speed of 70.28 ± 3.84 km/h in a random order. The swing velocity, wrist vibration, forearm muscle activation, and co-contraction ratio during hitting phases were analysed. The results indicated that the swing velocity during each specific phase demonstrated no significant differences between the different conditions. Hitting weighted and pitched baseballs caused higher wrist vibration, muscle activation, and co-contraction ratio during the contact phase than hitting regulation balls (p < 0.05). The conclusion was that hitting weighted baseballs could mimic the impact condition of hitting pitched baseballs without changing the pattern of swing velocity, which suggested that this method has potential as a hitting drill for improving hitting perception at bat–ball contact.