The Run Style Spectrum

The Run Style Spectrum describes the most fundamental parameters of running technique and is therefore paramount for any analysis and interpretation. The Run Style Spectrum is based on the notion that all limb movements and muscular forces aim at transporting the body as a whole. The Run Style Spectrum describes the sinusoidal Body Centre of Mass (BCoM) trajectory. 

The main characteristics to describe the BCoM trajectory are step frequency and the duty factor (the ratio of stance time and stride time) as assessed at a given speed. These parameters culminate in a framework that describes the full spectrum of running styles. 

Based on this Run Style Spectrum, the ground reaction forces, forces within the body and segmental movements can be predicted. Furthermore, energy expenditure, force capacity and local mechanical loading can be clarified using the Run Style Spectrum. 

Each running style requires specific energy and force capacities. For example, to run at low step frequencies (Push) requires high force generation capacities, while running at high step frequencies (Hop) will require good coordination and endurance. Running with long flight phases (Bounce) will require high elastic energy capacity and strong tendons. Consequently, problems with the Achilles tendon are likely related to the Bounce-style runners. 

Local mechanical loading also depends on the kinematics of each running style. For example, the longer stance times (Stick) arise from foot placement anterior to the body. The Stick-style runners may especially be susceptible to tibialis-located injuries. 

As described, each running style is associated with a specific injury risk profile. Without changes in the running style, the local mechanical loading will remain the same. Thus, when a particular running style results in an injury, the injury is likely to repeat. For the treatment and prevention of running, injuries clinicians and coaches should consider gait retraining.