Biomechanics Analysis of the Lower Limbs in 20 Male Sprinters Using the International Society of Biomechanics Six-Degrees-of-Freedom Model and the Conventional Gait Model

BACKGROUND: This biomechanics study of the lower limbs aimed to compare the use of the International Society of Biomechanics Six-Degrees-of-Freedom (ISB-6DOF) model and the conventional gait model (CGM), formerly known as the Helen Hayes model, in 20 male sprinters who habitually used the forefoot (FF) or rearfoot (RF) strike modes. MATERIAL/METHODS: We used a motion capture system to compare the difference in lower-extremity joint mechanics between sprinters’ forefoot or rearfoot strike mode during unplanned sidestepping (UPSS). Twenty elite sprinters participated in a motion capture test under 2 models. Each of the 10 participants were classified as having a habitual forefoot strike mode or rearfoot strike mode during unplanned sidestepping. Joint mechanics and gait parameters were calculated according to the designed movement. RESULTS: Comparison of the 2 models showed that the knee joint angles were inconsistent (P<0.05), highlighting the difficulty of the Helen Hayes model in anatomical recognition. The results of the 2 models show that during the unplanned sidestepping, the sprinter using the habitual rearfoot strike mode had a greater load through the knee joint (P<0.05). Sprinters who used the habitual forefoot strike mode experienced greater load through their ankle joints (P<0.05). CONCLUSIONS: The findings from this biomechanics study showed that when compared with the ISB-6DoF model, the findings from the CGM were more reproducible for the evaluation of FF and RF strike during unplanned sidestepping.