Lower limb joint kinetics during the first stance phase in athletics sprinting: three elite athlete case studies

TLDR

The study examined first‑stance joint kinetics in three elite sprinters to understand technique differences and their impact on performance. The authors recorded 1000‑Hz force and 200‑Hz video data to compute moments, power, and work at the MTP, ankle, knee, and hip joints during stance. The analysis revealed that the ankle produced up to four times more energy than it absorbed, the MTP mainly absorbed energy, knee extensor moments and power were sustained throughout stance with the top sprinter generating up to four times more knee energy, and hip extension occurred early with subsequent energy absorption, indicating ankle energy generation is crucial for later sprint phases while knee energy generation supports early acceleration.

Abstract

This study analysed the first stance phase joint kinetics of three elite sprinters to improve the understanding of technique and investigate how individual differences in technique could influence the resulting levels of performance. Force (1000 Hz) and video (200 Hz) data were collected and resultant moments, power and work at the stance leg metatarsal-phalangeal (MTP), ankle, knee and hip joints were calculated. The MTP and ankle joints both exhibited resultant plantarflexor moments throughout stance. Whilst the ankle joint generated up to four times more energy than it absorbed, the MTP joint was primarily an energy absorber. Knee extensor resultant moments and power were produced throughout the majority of stance, and the best-performing sprinter generated double and four times the amount of knee joint energy compared to the other two sprinters. The hip joint extended throughout stance. Positive hip extensor energy was generated during early stance before energy was absorbed at the hip as the resultant moment became flexor-dominant towards toe-off. The generation of energy at the ankle appears to be of greater importance than in later phases of a sprint, whilst knee joint energy generation may be vital for early acceleration and is potentially facilitated by favourable kinematics at touchdown.