Professional skateboarding trousers design: according to the three-dimensional kinematic analysis for varied skateboarding manoeuvres

The popularity of skateboarding has caused an expansion of enthusiasts worldwide. Moreover, skateboarding is becoming increasingly professional at an international level. Professional skateboarding trousers are regarded as critical equipment and their design research should not be overlooked. This research aims to use motion capture to measure the angular changes characteristics of critical lower limb joints in skaters during sports activities, measure the length of the knee joint during actions, and establish a formula that describes the change characteristics between the angle and the length. The formula would allow for a data reference when designing the elasticity at the knee joints of skateboarding trousers. Thus, the initial step in this research methodology was to use a Vicon motion capture system to test and analyse the kinematic characteristics of seven skaters in the squat, jump, ollie, pop shove it, heel flip, kickflip, and 180° ollie. Based on the kinematic characteristics, the dynamic movements were broken down into static postures at 0°, 45°, 90°, 112.5°, and 135°. The body surface drawing method was then employed to measure changes in the knee joint body surface dimensions of the subjects. Next, the experimental data were analysed to explore the relationship between angle and length changes. Finally, the design was developed based on the data. Analysis and processing of the experimental data yielded the following conclusions: (1) The most significant knee joint change characteristics during skateboarding was the angle change observed during an ollie. (2) Knee joint skin stretch deformation is most evident in the anterior mid-leg line y2. (3) The relationship between kinematics and the structural design of skateboarding trousers was derived from the experimental data. Specifically, the equation for the relationship between angle change and length change is given by y2 = 0.0442x + 23.906. (4) The results show that the extreme range of skin stretching in the anterior midline is between –0.7 and 6.3 cm. Therefore, the loose design of the knee part of professional skateboarding trousers should not exceed 6.3 cm. This research approach can offer an effective design solution for professional skateboard trousers and can also be applied to other types of trousers.