Competitive Running involves: • Speed: To run fast • No injuries: Injury rates in runners range from 50-70% • Economy: Efficient running
Commonly held assumptions • Running is a simplistic movement. • Individual differences between athletes make it impossible to have a universal running technique (Nytro, 1987). • Sprinters and endurance runners require a different running technique. • Running is natural (Wallack, 2004).
How do we run? • What external force should we use and how should we evaluate our choice? • How should we interact with the ground? • What muscles should we use and how can we assess their efficiency?
Forces involved in running Ground reaction force (GRF) Muscle force Muscle elasticity Gravity (g)
Combining the external forces during stance GRF transferred to CM Direction of motion Resultant force CM Lower limb Gravity
Interplay of external and internal forces in running An internal (muscular) force acts on the upper part of the body. This force induces acceleration of the upper body upward. The reaction force acts on the bottom part of the body. This force is transmitted to the floor. Ground reaction force
Which external force should we use for running? Ground reaction force Centre of mass (CM) Force gravity (700 N) Force Horizontal Force gravity (700 N)
Muscle elasticity, rotational inertia and muscle work Gravitational force Radius of leg GRF
Biomechanical variables video
How should we evaluate technique? • “I was told over and over again that I would never be successful, that I was not going to be competitive and the technique was simply not going to work. All I could do was shrug and say 'We'll just have to see'.” • Dick Fosbury won an Olympic gold medal at the 1968 Mexico City Games after he invented a revolutionary high-jump technique: the Fosbury-flop.