Simulations Reveal How Touchdown Kinematic Variables Affect Top Sprinting Speed: Implications for Coaching

Area of Science:

• Biomechanics
• Sports Science
• Human Movement

Background:

• Sprint performance is crucial for athletes and coaches.
• Kinematic variables like horizontal touchdown distance (HTD) and inter-knee touchdown distance (IKTD) are key targets for improving sprint speed.
• Previous research on these variables has yielded conflicting results, hindering the establishment of clear cause-effect relationships.

Purpose of the Study:

• To investigate the cause-effect relationships between HTD, IKTD, and sprinting speed using a predictive simulation approach.
• To determine if specific adjustments to HTD and IKTD can enhance top sprinting speed.
• To provide a simulation framework for further research into sprinting biomechanics.

Main Methods:

• A predictive simulation approach was employed using a scaled 3D musculoskeletal model of an international male sprinter.
• A direct collocation optimal control framework generated simulations of a single, symmetric step of top-speed sprinting.
• Simulations were run to establish optimal top speed, followed by simulations with enforced variations in HTD and IKTD (± 2, 4, 6 cm).

Main Results:

• The optimal simulation achieved a top sprinting speed of 11.85 m/s.
• Shortening HTD by 6 cm decreased speed by 7.3%, while lengthening it by 6 cm reduced speed by only 1.6%.
• Altering IKTD within the tested range (± 2, 4, 6 cm) showed no significant impact on simulated sprinting speed.

Conclusions:

• An optimal horizontal touchdown distance (HTD) exists to maximize sprinting speed, supporting its use as a technical focus for coaches and athletes.
• Adjusting inter-knee touchdown distance (IKTD) does not appear to be an effective strategy for enhancing sprint speed.
• The developed simulation framework is publicly available for further exploration of sprinting biomechanics and performance optimization.