The kinematic analysis of the lower limb during topspin forehand loop between different level table tennis athletes

Background: Topspin is one of the most attacking stroke in table tennis sport. The aim of this research was to investigate the kinematic characteristics of the lower limb (driving leg) during topspin forehand loop in different playing level table tennis athletes. Methods: Ten male table tennis athletes performed topspin forehand loop shots with maximal force to hit the ball that was played by a professional table tennis coach. The three-dimensional Vicon motion analysis system was used to capture the kinematic information. Results: The key findings from this research indicate that there were no significant differences in motion time between elite athletes (EA) and medium athletes (MA) during the entire phase (P = 0.784). EA showed significantly less knee (P < 0.001) as well as hip (P < 0.001) flexion in the BS stage when contrasted to MA, with a significant larger ankle varus (P = 0.003) as well as eversion (P < 0.001) than MA in the BS and FS phase, respectively. EA displayed a significant larger angular changing rate of ankle dorsiflexion (P < 0.001) and varus (P < 0.001) in the BS stage with ankle plantar flexion as well as eversion during the FS stage, with a significant larger ankle internal rotation (P = 0.003) and external rotation (P < 0.001) than MA in the BS and FS phase, respectively. Furthermore, EA showed significantly larger ankle dorsiflexion (P = 0.001) as well as plantarflexion (P < 0.001) ROM in the BS and FS phase respectively compared with MA. Conclusion: Ankle activities in the all plane displayed significant differences in kinematic characteristics between EA and MA. MA should pay attention to the function that ankle played in the kinetic chain, such as training the lower limb muscle rapid reaction ability to improve the energy transfer efficiency and capability of the kinetic chain.