Kinematic analysis of sprint running for injury prevention: A case study

Sprint running represents the most popular specialty in trackand- field sports. Several studies investigated the parameters influencing the performance. 3D kinematic analysis is fundamental to determine these parameters to build an appropriate training and to identify possible anomalies that can point out a risk of injury. In several studies only the performance is highlighted, without any investigation on the possible causes of injury, such as proximal femoral biceps tendon inflammation. The aim of the present study was to investigate the possible cause of an injury occurred after the acquisition to one analysed athlete. The analysis was performed comparing the relevant sprint running kinematics of an athlete with the same type of injury with the kinematics of four healthy athletes. Six medium level male athletes (height 180±4 cm, weight 79±8 kg, personal record on 100m 11.10±0.60 s) were analysed with the Vicon Motion System 460 (100 Hz, resolution of 300,000 pixel, 6–8 cameras). Four of them were healthy, onewas pre-injured (AR) and 1 post-injured. The injury was the proximal femoral biceps tendon inflammation. During the stance phase of the low leg the following data were analysed: flexion/extension angle at foot strike and toe-off and angular velocity (maximum and minimum) of hip and knee joint (for the latter the maxim flexion angle during gathering was also calculated). AR showed differences in joint flexion/extension angles between the right and the left lower limb, particularly at the toe-off (11.9◦ and 11.6◦at hip and knee extension, respectively). On the contrary, the healthy athletes showed similar joint flexion/extension angles between the two lower limbs with a mean difference of 2.4◦ and 1.8◦ at hip and knee joint, respectively. The maximum angular velocity values of the two legs of AR were also different: 191◦ s−1 for the hip flexion with respect to 101◦ s−1 (mean value over the four healthy athletes) and 145◦ s−1 for knee flexion and 227 ◦ s−1 for knee extension with respect to 47◦ s−1 and 29◦ s−1. Results showed a higher range of motion for the left leg of AR during the stance phase. SF, showed a pattern similar to AR, but in the right lower limb. The difference between the two limbs and between the mean flexion/extension angles was particularly marked at the toe-off (17◦ of higher extension at the hip and16.4◦ at the knee). AR showed an asymmetry between the right and left lower limbs during sprint running. This behaviour is supposed to have created a wrong load distribution: 2 months after the acquisition AR had a proximal femoral biceps tendon inflammation causing a long agonistic suspension. This hypothesis is supported by the data acquired for SF: after an injury similar to the one occurred to AR, but on the opposite limb, the same kinematic asymmetry on the right limb was observed.